Protein phosphorylation/dephosphorylation is a major signalling event induced by abiotic stresses in plants. Sucrose nonfermenting 1-related protein kinase 2 (SnRK2) plays important roles in response to osmotic stress. In the present study, four SnRK2s, TpSnRK2.1/3/7/8, were cloned and characterized from Triticum polonicum L. (dwarf Polish wheat, DPW, AABB). All of these were individually located on 2AL, 1AL, 2AL, and 5BL. Two spliced isoforms of TpSnRK2.8 (TpSnRK2.8a and TpSnRK2.8b) were observed. TpSnRK2.1 and TpSnRK2.3 were classified into the group II; TpSnRK2.7 was classified into the group I; and TpSnRK2.8a/b were classified into the group III. Expression patterns revealed that TpSnRK2.1 responded to cold, NaCl, polyethylene glycol (PEG), and abscisic acid (ABA) in both roots and leaves; TpSnRK2.3 was strongly regulated by cold, NaCl, and ABA in both roots and leaves, and by PEG in roots; TpSnRK2.7 was induced by NaCl and PEG in roots, but was not activated by ABA; and TpSnRK2.8s were significantly activated by cold, NaCl, PEG, and ABA in both roots and leaves. From the above results, we inferred that TpSnRK2.1/3/8 may participate in the responses to environmental stresses in ABA-dependent signal transduction pathway but TpSnRK2.7 is possibly involved in responses to environmental stresses in a non-ABA-dependent manner. They play important roles in specific tissues under different stresses.

Ion transporters play an important role in ion homeostasis and control ion flow from its intrusion to exclusion in the entire plant system. Abiotic stress tolerance in plants depends immensely on the activity of these transporters. The transporter proteins are transcriptionally regulated by cis-elements present in their upstream region for specific activity. The presence of different cis-elements facilitates cross-talk between different signal transduction pathways. Depending on the cis-elements, a specific stress signalling pathway is activated, eliciting a physiological change towards maintaining ion homeostasis to alleviate stress. Beta-glucuronidase localization studies using various promoter regions indicated their expression specificity in organs/tissues. This review gives an overview about promoter activity of different transporters and its involvement under salinity stress.

Low temperature can affect the growth and development of lily, limiting the application of commercial cultivars in outdoor. Lilium lancifolium is an important cold-resistant wild lily, but little is known about how L. lancifolium tolerates cold stress at the molecular level. In this study, we identified and characterized genes and transcription factors associated with cold stress in control plants and plants treated by 4° C for 1 - 24 h. The construction of a highest reciprocal rank-based gene co-expression network along with its partition into defined functional modules using Markov cluster algorithm resulted in identification of 30 gene modules and some of them were significantly enriched with various kinds of stress response under 4° C. These gene modules were associated with metabolic processes, cellular processes, regulation of biological processes, establishment of localization, and responses to stimuli. Moreover, three transcription factors that may regulate the downstream genes involved in response to stimuli were also found. We further studied the expression pattern and tissue specificity of these transcription factors. The functional evaluation of the various interesting genes in this study will probably provide novel discovery of pathway members and regulators associated with cold resistance in lily.

The present work aimed to investigate the mechanisms of nitric oxide (NO) and reactive oxygen species (ROS) generations and to explore their roles in the regulation of antioxidative responses in the wheat leaves under salinity. Except for an insignificant change of NO content and nitrate reductase (NR) activity due to 50 mM NaCl, NO, hydrogen peroxide, superoxide anion (O₂^*- ), hydroxyl radical (^*OH), chlorophyll and malondialdehyde content, as well as activities of nitric oxide synthase, NR, peroxidases (POD), catalase (CAT), and ascorbate peroxidase rose in response to different NaCl concentrations. Meanwhile, leaf superoxide dismutase activity lowered only at 50 mM NaCl. NaClstimulatory effects on NO content as well as POD and CAT activities could be partly alleviated by the application of 2-phenyl-4,4,5,5-tetrame-thylimidazoline-3-oxide-1-oxyl (PTIO, NO scavenger), exogenous CAT, or diphenylene iodonium (DPI, NADPH oxidase inhibitor). Native polyacrylamide gel electrophoresis (native-PAGE) also showed that the amount of POD (especially POD4, POD5, and POD7) and CAT (especially CAT1, CAT2, and CAT3) isozymes increased with increasing salinity but decreased by application of PTIO, CAT, or DPI. Furthermore, histochemical staining showed a similar change of O₂^*- generation. In addition, the inhibition of diamineoxidase (DAO), polyamine oxidase (PAO), and cell wall-bound POD (cw-POD) activities in NaCl-stressed seedlings seemed to be insensitive to the application of PTIO or DPI. Taken together, salinity-induced NO, H₂O₂, and O₂^*- generation influenced each other and played different roles in the regulation of antioxidant enzyme activities in the leaves of wheat seedlings under NaCl treatment.

Aluminum (Al) toxicity in acidic soils is a major factor restricting crop production. Although the molecular mechanisms of Al responses have been extensively investigated, microRNA (miRNA) mediated differential Al tolerance in different soybean genotypes remains largely unknown. In this study, two soybean [Glycine max (L.) Merr.] genotypes, Al-tolerant BX10 and Al-sensitive BD2, were treated with 0 and 50 μM AlCl3 and then used to construct the miRNA libraries for deep sequencing. Results revealed 453 miRNAs, whose expression patterns were affected by Al stress. We also identified 32 differentially expressed miRNAs: 19 in BX10, 7 in BD2, and 6 in both genotypes. The gene ontology analysis of their putative target genes indicated that stress-responsive genes and amino-acid-metabolism-related processes preferentially existed in BX10. Comprehensive analysis demonstrated that conserved miRNAs, such as gma-miR166k/o, gma-miR390g, and gma-miR396c/k, mediated root elongation in BX10, whereas gma-miR169r triggered oxidative stress in BD2. These processes could be regarded as important mechanisms conferring differential Al tolerance in BX10 and BD2. This study provided new insights into different Al response mechanisms in various soybean genotypes.

Structural alterations of chromosomes are often found in wheat-rye hybrids. In the majority of cases modifications are observed for rye chromosomes, yet chromosome aberration cases are described for wheat, including the progeny of Triticum aestivum disomic and monosomic addition lines. Since wheat-rye substitution and translocation lines are the source of rye chromatin in wheat breeding programs, the information on possible chromosome changes in the genomes of introgressive forms is important. Chromosome behavior in F₁ meiosis and chromosomal composition of F₂ karyotypes for double monosomics 1Rv-1A were studied by applying C-banding, genomic in situ hybridisation (GISH) using rye genomic DNA, and sequential in situ hybridization using repetitive sequences pAs1, pSc119.2 and centromere specific pAet-06 as probes. The double monosomics 1Rv-1A were obtained by crossing of disomic substitution line with chromosome 1A replaced by Secale cereale 1Rv in the bread wheat Saratovskaya 29 (S29) background with S29. The results indicated a high frequency of bipolar chromosome 1Rv orientation, as compared to 1A, at metaphase I (MI) (58.6 and 34.7 % of meiocytes, respectively), and, at anaphase I (AI), chromatid segregation of 1Rv compared to 1A (70.53 and 32.14 % of meiocytes, respectively). In few cases desynapsis of wheat homologues was observed, at AI, the chromosomes randomly distributed between the poles or underwent chromatid segregation. At AI, the two wheat homologues separated onto sister chromatids in 10.89 % of cells.The plants F2 karyotypes were marked with aneuploidy not only of chromosomes 1A and 1Rv, but also of 1D, 2D, 3D, 3B, 3A, 4A, 6D, 6B, 6A, and 7D. Structural changes were observed for the chromosomes of the first homoeologous group (1Rv, 1A, 1D, 1B), as well as for 2B, 5D, 6B, and 7B. The chromosomes 1Rv and 6B often demonstrated aberrations. The types of aberrations were centromeric break, deletions of various sizes, and a changed repeat pSc119.2 localization pattern.

Phosphites (Phis), inorganic salts of phosphorous acid, have shown to be effective in protection of plants against biotic stress. Recently, we have described that potassium phosphite (KPhi) induces tolerance to UV-B radiation in potato. To counteract the harmful effect of UV radiation, plants accumulate UV-screening compounds, such as flavonoids, sinapate ester, and lignin. In previous work, we have shown an increase in guaiacol peroxidase (POD) activity in plants pretreated with KPhi and further exposed to UV-B radiation. In order to continue with this study, the expression of different enzymes and components involved in cell wall reinforcement were analyzed. An isoform of POD induced by KPhi was analyzed by isoelectric focusing and further identified as suberization-associated anionic peroxidase (POPA) by mass spectrometry. In addition, other enzymes participating in lignin biosynthesis, like caffeoyl-CoA O-methyltransferase (CCoAOMT), determined by accumulation of transcripts, and laccase activity, visualized in zymogrames, were increased by KPhi treatment previous to UV-B exposure. Further, the accumulations of extensin (EXT) transcripts and of conjugated polyamines (PAs) were increased by KPhi treatment previous to UV-B exposure. All these results suggest cell wall reinforcement in leaves due to KPhi pretreatment followed by UV-B exposure.

In non-heading Chinese cabbage, the yield relies mostly on the health of leaves, which can be heavily impacted by turnip mosaic virus (TuMV). The virions or viral ribonucleoprotein complexes are transported through the phloem and xylem. Plasmodesmata are indispensable because they traverse cell walls and connect companion cells, allowing virus particles long distance movement. However, which complexes and genes participate in this process is still unknown. Plants can activate defense mechanisms and apply disease resistance genes to respond to pathogen attacks. In this study, we collected the stems and petioles infected by TuMV for 7 d (TuMV-7), 14 d (TuMV-14), and 21 d (TuMV-21). Using isobaric tags for relative and absolute quantification-based proteomic technology, 6 043 distinct proteins were identified and 323, 240, 285, 203, 253, and 363 differentially expressed proteins were found in the comparable pairs of TuMV-7/control, TuMV-14/TuMV-7, TuMV-14/control, TuMV-21/TuMV-7, TuMV-21/TuMV-14, and TuMV-21/control, respectively. We performed a functional annotation analysis of all identified proteins and a functional enrichment analysis of all differentially expressed proteins. The results indicated that the long distance movement of TuMV involved many complex regulatory pathways. The respective proteins were related to those occurring in plasmodesmata and to Ca²⁺ transporters. Further, we also found proteins related to heat shock proteins, pathogenesis-related proteins, and proteins scavenging reactive oxygen species.

Plants are severely affected by many biotic stresses, which cause a reduction in crop quality and quantity. One of the strategies to manage biotic stresses is the generation of transgenic plant lines that can be used as biosensors. These biosensor plants can trigger an early warning upon any pathogen infection. Two promoters with β-glucuronidase reporter gene fusions were constructed. The first contained the flagellin sensing 2 gene promoter, whereas the second contained synthetic promoter containing four repeats of cis-acting elements from the pathogen-related protein 1 gene and two transcription enhancers from the 35S promoter. Transformed leaves were treated with a phytohormone salicylic acid to mimic the occurrence of biotic stress. Validation of reporter gene expression induced from both constructs in transformed potato leaves displayed an increase upon salicylic acid treatment. The results reflect that both constructs could serve in the production of potato biotic stress biosensors.

A gene encoding Mn-containing superoxide dismutase (Mn-SOD), designated as ThMSD, was cloned from salt cress (Eutrema halophilum) by reverse transcriptase - polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). The full length of ThMSD (acc. No. EF413171) is 1 047 bp with an open reading frame (ORF) of 693 bp. The deduced 231-amino acid polypeptide had a predicted molecular mass of 25.5 kDa, an estimated pI of 9.08, and a putative Mn-binding site. Recombinant ThMSD protein was expressed in Escherichia coli and characterized. The SOD activity of ThMSD was inactivated by sodium azide but not by potassium cyanide or hydrogen peroxide confirming that ThMSD is a Mn-SOD. Real-time PCR revealed that ThMSD was expressed in roots, rosette leaves, stems, stem leaves, flowers, and siliques. ThMSD mRNA reached the highest content in roots and its content increased when plants were treated with NaCl (in a concentration dependent manner), ABA, and subjected to drought. ThMSD was transformed into Arabidopsis and the stress tolerance properties of transgenic lines were assayed. The seeds of transgenic lines exhibited significantly higher germination rate under 100 and 150 mM NaCl than the wild type. The root growth of transgenic lines was affected less obviously than the wild type under 100 mM NaCl. The above results indicate that ThMSD played an important role in E. halophilum tolerance to environmental stresses, especially NaCl stress.

Di-n-butyl phthalate (DBP) is one of the frequently detected phthalates in environmental samples. The effects of phthalates are extensively studied in the animals but the effects on plants are scarce. Therefore, the present study is aimed to envisage the effects of DBP on the antioxidative defense system in Hordeum vulgare L. seedlings grown under laboratory conditions for 7 d. The activities of different antioxidative enzymes were enhanced in the shoots. In the roots, the activity of guaiacol peroxidase increased and the catalase activity decreased initially but increased at higher DBP concentrations, whereas the activities of superoxide dismutase, ascorbate peroxidase, and glutathione reductase declined. Furthermore, the content of polyphenols elevated after exposure of seedlings to DBP. The possible reason for these responses of barley seedlings is the oxidative burst, i.e., enhanced production of reactive oxygen species, which were confirmed using confocal microscopy in terms of loss in plasma membrane integrity. DBP also disturbed the normal stomatal morphology of barley seedlings. The study may help to provide insights into the defense of crop plants against phthalate stress.

Cadmium (Cd) is a highly toxic and widespread soil pollutant, which negatively affects various aspects of plant growth and physiology. Here, the role of photosynthesis in response to Cd was investigated in the Cd-tolerant pea (Pisum sativum L.) mutant SGECd^t. The wild type SGE and the mutant SGECd^t were grown in a hydroponic solution supplemented with 1, 3, or 4 µM CdCl₂ for 12 d. Root and shoot biomasses of the Cd-treated SGECd^t were significantly higher than of SGE. Cadmium had little effect on the quantum yield of photosystem II (φPSII) and chlorophyll content of intact leaves of both pea genotypes. However, when leaf slices were taken from Cd-exposed plants and incubated with high Cd concentrations, the SGECd^t mutant showed 1.5 - 2 times higher φPSII values than SGE, with genotypic differences maximal at 0.1 and 1 mM CdCl₂. In contrast, when leaf slices were taken from plants previously unexposed to Cd, both pea genotypes exhibited similar φPSII values. Cadmium content in leaves and mesophyll protoplasts of Cd-treated SGECd^t were about 2 - 3 times higher than in SGE ones. The mutant leaves and mesophyll protoplasts had also higher Ca, Mg, Mn, and Zn content. Thus, SGECd^t acclimated to Cd during growth in the Cd-supplemented nutrient solution by developing a molecular mechanism related to photosynthetic integrity. A higher foliar nutrient content likely allows enhanced photosynthesis by counteracting the damage of leaves caused by Cd.

Salinity adversely affects plants resulting in disruption to plant growth and physiology. Previously, it has been shown that these negative effects can be alleviated by various exogenous polyamines. However, the role of spermidine (Spd) in conferring salinity tolerance in sorghum is not well documented. The effect of exogenous Spd on the responses of sweet sorghum (Sorghum bicolor L.) seedlings to salt stress (150 mM NaCl) was investigated by measuring photosynthetic carbon assimilation, Calvin cycle enzyme activities, and the the expression of respective genes. Application of 0.25 mM Spd alleviated the negative effects of salt stress on efficiency of photosystem II and CO₂ assimilation and increased the activities of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) and aldolase. Salt stress significantly lowered the transcriptions of genes encoding Rubisco large subunit, Rubisco small subunit, 3-phosphoglyceric acid kinase, glyceraldehyde-3-phosphate dehydrogenase, triose-3-phosphate isomerase, fructose-1,6-bisphosphate aldolase, fructose-1,6-bisphosphate phosphatase, and sedoheptulose-1,7-bisphosphatase. However, transcriptions of genes encoding phosphoribokinase and Rubisco were up-regulated. The Spd application enhanced expressions of most of these genes. It appears Spd conferred salinity tolerance to sweet sorghum seedlings by enhancing photosynthetic efficiency through regulation of gene expressions and activities of key CO₂ assimilation enzymes.

The WRKY belongs to an important plant specific transcription factor families which are involved in response to various environmental stresses, as well as in growth and developmental processes. In the present report, a genome-wide identification and characterization of WRKY gene family in barley led to revision of HvWRKYs to 93 members. The phylogenetic tree was also reconstructed based on the full-length WRKY protein sequences in barley and Arabidopsis. HvWRKYs were classified into three major groups (I, II, and III) and group II was further divided to 5 subgroups (a to e). HvWRKYs were named after this classification. Interestingly, some specific motifs were discovered in subgroups IIa, IIb, and III. Analyzing the available microarray data revealed eight candidate WRKY genes which were up-regulated under drought and salinity stresses compared to the optimum conditions at seedling stage in barley. Expression profiles of these WRKY genes were validated by quantitative real-time PCR. All the investigated candidate genes (HvWRKY_IIc2, HvWRKY_III11, HvWRKY_IIb2, HvWRKY_IId4, HvWRKY_III23, HvWRKY_IIa5 and HvWRKY_IIc19) except for HvWRKY_I8 were significantly up-regulated by drought stress at the seedling stage in drought-tolerant genotype, indicating their role in drought tolerance. We hope the presented information would be helpful toward achieving drought tolerant cultivars through genetic engineering or molecular breeding.

Heat stress is one of the most crucial factors affecting crop growth and productivity worldwide. So, searching for a potent eco-friendly heat stress alleviator is the main issue nowadays. The current study was conducted to assess the ameliorative effects of 1.5 mM potassium silicate (K₂SiO₃, further only Si) or 1.66 mM silicon dioxide nanoparticles (SiNPs) on wheat (Triticum aestivum L.) seedlings exposed to heat stress (45 °C, 4 h). The observations show that Si or SiNPs treatments significantly restored the heat stress-provoked ultrastructural distortions of cellular organelles, particularly chloroplasts and the nucleus. Further, both Si and SiNPs enhanced the photosynthetic capacity as revealed by increments in the photochemical efficiency of photosystem II and the performance index as well as the content of photosynthetic pigments. A reduction in malondialdehyde accumulation in Si and SiNPs treated plants was positively related to their membrane stability index. The reverse transcription PCR analysis showed that Si treatment but not SiNP treatment stimulated the overexpressions of both Triticum aestivum plasma membrane intrinsic protein (TaPIP1) and Triticum aestivum nodulin 26-like intrinsic protein (TaNIP2) aquaporin genes parallelly with an improvement in the relative water content. This investigation reveals that Si was more effective than SiNPs in restoring the heat stress injuries. To the best of our knowledge, this is the first investigation exploring the effects of Si and SiNPs in improving thermotolerance of wheat seedlings.

Uridine diphosphate glucose dehydrogenase (UGDH) is a key enzyme in the hemicellulose and pectin biosynthesis pathway and participates in the regulation of growth and development in plants. In this study, we isolated a BpUGDH gene from paper mulberry (Broussonetia kazinoki × Broussonetia papyifera) and analyzed its function and expression characteristics. The results show that the BpUGDH was expressed in all organs of paper mulberry with a higher expression in stems than in leaves and roots. A pBpUGDH::GUS gene construct was highly expressed in transgenic Arabidopsis thaliana seedlings, and its expression was induced by a low temperature, methyl jasmonate, gibberellin A₃, ethylene, and auxin. The overexpression of BpUGDH increased the soluble sugar content, promoted the accumulation of hemicellulose, and enhanced the vegetative growth of transgenic plants. These results provide a basis for regulating the growth and adaptability of paper mulberry and improving its utilization value via genetic modification of the BpUGDH gene.

To study the biological function of late embryogenesis abundant (LEA) proteins in Lepidium apetalum Willd., genes encoding LEA family proteins were identified from the seed transcriptome. The sequence most closely related to germination at a low temperature was selected and gene expressions in response to low temperature stress further studied. The results show that 27 LEA genes were expressed in seeds germinating at the low temperature: 3 genes were upregulated, 20 were downregulated, and 4 were not significantly different from controls. The most prominent of the upregulated genes, LaLEA1, contained an open reading frame of 624 bp and encoded 208 amino acids. The protein was rich in hydrophilic amino acids including threonine, alanine, glutamine, and lysine. It is predicted that the secondary structure contains α-helices and irregular curls. Real-time quantitative PCR results show that under low temperature stress, the expression of LaLEA1 was first downregulated and then upregulated rapidly, reaching its highest expression at 12 h, then the expression of LaLEA1 was reduced slightly but maintained higher than that of the non-stress group. As the expression of LaLEA1 was significantly altered in response to low temperature stress, we investigated the expression of LaLEA1 also in response to other abiotic stresses, i.e., salinity and drought. L. apetalum seedlings wilted in the early stage following NaCl or osmotic (polyethylene glycol) stresses, but recovered quickly, showing a strong tolerance. Real-time quantitative PCR results show that LaLEA1 was rapidly upregulated following salt and osmotic stresses, and its expression profile was closely related to NaCl or PEG concentrations. Expression was up to 7.9-fold higher than that of the control after 6 h of salt stress. These results suggest that L. apetalum seedlings responded quickly to salt stress. The response to osmotic stress was slightly slower; expression of LaLEA1 was 6.0-fold higher than that of the control after 12 h. Thus, LaLEA1 played an important role in abiotic stress tolerance. These results provide a basis for further analysis of the role of the LEA genes in the stress resistance of L. apetalum.

Circular RNAs (circRNAs), an emerging class of non-coding RNAs, are abundant in eukaryotic transcriptomes. Seed germination is one of the most important stages in the entire life cycle of plants that can be slowed down or totally restrained by high temperature. Our aim is to identify heat-responsive circRNAs and explore the potential function of circRNAs in tomato seeds at high temperature. Following high-throughput sequencing, 4 164 circRNAs were identified, and 980 circRNAs were shared in the control and high-temperature libraries. Among the 748 circRNAs with high expressions, 73 circRNAs were significantly up-/down- regulated in tomato seeds germinated at high temperature compared to the control. The parental genes of circRNAs existing in seeds only at high temperature were mainly involved in metabolic processes, cellular processes, catalytic activities, and binding based on Gene Ontology analysis. The results suggested that circRNAs were widespread in tomato and were generated from different chromosomes and diverse genomic regions. Some circRNAs in tomato seeds responded to high temperature during germination. This study provides the first genome-wide profile of circRNAs in response to high temperature during tomato seed germination and lays a foundation for studying the potential biological functions of circRNAs responding to heat stress.

In order to reveal the role of sucrose (Suc) in early drought response in plants, transgenic rice (Oryza sativa L.) plants overexpressing the maize (Zea mays L.) C₄-phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) gene (C₄-pepc) (PC) and their untransformed wild type (WT) were used under 12 % (m/v) polyethylene glycol 6000 to simulate drought conditions. The results showed that PC has higher relative water content, the increased Suc content, and anthocyanin accumulation than WT during PEG treatment. By spraying 1 % Suc and 1 % Suc non-metabolic analog, turanose, on these plants, Suc in PC leaves increased anthocyanin content and Ca²⁺ content. Further experiments using the Ca²⁺ chelator (EGTA), Ca²⁺ channel antagonist (ruthenium red), and abscisic acid inhibitor (nordihydroguaiaretic acid), showed that, in PC plants, Suc content is closely related to the expression of sucrose nonfermenting-1-related protein kinases 2 (SnRK2s) such as SAPK8, SAPK9, and SAPK10 via abscisic acid, and the SnRK3 such as SnRK3.1, SnRK 3.4, and SnRK3.21 via Ca²⁺ and calcineurin B-like as well. Furthermore, the target genes associated with anthocyanin synthesis phenylalanine ammonia lyase, chalcone isomerase, chalcone synthase, flavonoid-3-hydrogenase, flavonoid-3'-hydrogenase, dihydroflavonone reductase, and anthocyanin synthase, their regulated genes basic helix-loop-helix (bHLH) proteins OsB1 and OsB2, R2R3-MYB transcription factor OsC1, and some transcription factors (constitutively photomorphogenic 1, elongated hypocotyl 5, and purple acid phosphatase gene 2) in PC plants also increased via Suc and Ca²⁺ during the PEG treatment. Some Suc tranporter genes OsSUT1 and OsSUT5 in PC lines during PEG treatment further showed an enhancement for the function of the signal of Suc. Thereby, increasing anthocyanin biosynthesis via Suc and Ca²⁺ signaling cascade is one of the important mechanisms on drought tolerance in the PC lines.

Tetraploid wheat (Triticum turgidum L.) is an important species within the genus Triticum and harbors many desirable agronomic traits. The classification, origin, and evolution of tetraploid wheat remain confused and controversial, resulting in useless germplasm resources. Two classification systems for tetraploid wheat are widely used: 1) tetraploid wheat comprises two species; 2) all forms of tetraploid wheat are classified as one species. The present study aimed to reassess the classification of tetraploid wheat using phylogenetic analysis of nuclear rDNA internal transcribed spacer region (ITS) sequence data, fluorescence in situ hybridization (FISH) karyotyping, and observation of meiotic pairing behavior in F₁ hybrids. Network analysis of ITS sequences indicates that tetraploid wheat was not closely related to other Triticeae species with the exception of Aegilops speltoides and Ae. sharonensis. Phylogenetic analysis of ITS sequences and FISH show that Triticum turgidum and T. timopheevii clustered on distinct branches, and meiotic pairing in F₁ hybrids of these species showed a high frequency of univalents. Meiotic behavior of F₁ hybrids among forms of T. turgidum revealed a low number of univalents (means < 2) except for T. turgidum ssp. dicoccoides. The significant variation on chromosomes 1A, 2A, 5A, 1B, 2B, 3B, and 6B in the FISH hybridization patterns were observed between T. turgidum ssp. dicoccoides and other T. turgidum accessions. Furthermore, the results of ITS phylogenetic analyses correspond closely with observations of meiotic behavior and FISH karyotyping. The present results indicate that T. turgidum and T. timopheevii are two distantly related species of different origins. Triticum turgidum ssp. dicoccoides should be maintained as a subspecies of T. turgidum whereas other forms of T. turgidum should be reclassified as varieties.

Real time quantitative PCR (qPCR) is a powerful tool for studying the expression of specific genes. The accuracy and reliability of qPCR analysis data require the selection of reference genes with stable expression. However, the reference genes that can be used for qPCR of Rehmannia chingii and R. henryi have not yet been identified. In this study, based on the transcriptome data of R. chingii and R. henryi, we initially selected genes with relatively stable expression in different samples. We screened six candidate reference genes in R. chingii and R. henryi and calculated their expression abundance by real time qPCR. Their expression stability was evaluated by three algorithms geNorm, NormFinder, and BestKeeper. Although the results obtained by different algorithms were not completely consistent, R. chingii type 2A phosphatase activator TIP41 and R. chingii 18S ribosomal RNA had the highest expression stability in six different samples of R. chingii, and R. henryi 18S ribosomal RNA and R. henryi actin showed the most stable expression in different samples of R. henryi. In addition, based on transcriptome data, four genes were screened in R. chingii and R. henryi, and the expression stability of the selected reference genes was further verified. This study laid the foundation for further analysis and verification of the functions of important genes in R. chingii and R. henryi.

Since 1960, the positive effects of rare earth elements (REE) on crop physiology have been observed, and support for photosynthesis, biomass accumulation, secondary metabolites, or enzymes has been reported in 40% of studies. A higher content of chlorophylls a and b as well as carotenoids have been found along with an increased efficiency of photosystem II photochemistry and electron transfer rates. An increased activity of a key photosynthetic enzyme was also found in several plants growing in soil with a higher content of REE. An appropriate amount of REE also activates the antioxidant activity of peroxidase, superoxide dismutase, and catalase. These enzymes, together with a higher content of flavonoids and carotenoids, increase the resistance of plants to oxidative stress caused by different abiotic stresses. The positive effect of REE on biomass accumulation was also confirmed, but their affection on mycorrhizal symbiosis remains ambiguous. On the other hand, an excess of REE leads to damage to plants including the chloroplast ultrastructure. Therefore, the positive and negative effects of REE remain controversial, and the mechanisms of effects of REE in plants remain poorly understood. In addition to physiological processes, the absorption, bioavailability, and translocation of REE in plants as well as their possible ecotoxicology and hyperaccumulation are discussed in this review.

Sodium cation compartmentalization into vacuoles is one of the effective strategies for adaptation of halophytes to saline environments. Tonoplast Na⁺/H⁺ antiporter (NHX) is involved in Na⁺ sequestration into vacuoles under salt stress. However, the function of NHX in halophyte Iris lactea is still unclear. In this study, a significant positive correlation was observed between Na⁺ accumulations and IlNHX expression in tissues under 0 - 200 mM NaCl, indicating IlNHX might be responsible for Na⁺ accumulation of I. lactea under salt stress. More important, IlNHX was specifically localized to the tonoplast. Transgenic tobacco expressing IlNHX grew better and showed higher tolerance to 200 mM NaCl than respective wild type (WT). Compared to WT, transgenic tobacco accumulated more Na⁺ and K⁺ and maintained higher K⁺/Na⁺ ratios in tissues, accompanied by the reduction of chlorophyll loss and lipid peroxidation in the presence of NaCl. Moreover, transgenic tobacco exhibited markedly higher vacuolar H⁺-ATPase (V-ATPase) activity relative to WT when subjected to salt stress. The findings suggest that transgenic plants overexpressing IlNHX could compartmentalize more Na⁺ into vacuoles in tobacco via enhanced V-ATPase activity, which further contributes to maintaining K⁺ and Na⁺ homeostasis, to improved photosynthesis, and to protection of cell membrane integrity under salt stress.

In order to introduce drought tolerance and improved cell wall digestibility from fescue in fodder ryegrasses, we developed two amphiploid Festulolium synthetics. One is a synthetic composed of three selected drought tolerant F1 hybrid genotypes from a cross between tetraploid Lolium multiflorum and hexaploid Festuca arundinacea, further on called LMFA. The other is a synthetic composed of five selected genotypes with soft leaves from a cross between tetraploid Lolium perenne and tetraploid Festuca pratensis, further on called LPFP. We produced seeds in polycrosses of two generations of both amphiploids, i.e., syn1 and syn2, and tested them in plot trials to determine the yield and fodder quality. The syn1 of both Festulolium populations had a higher annual dry matter yield than the reference Lolium cultivars and Festulolium cultivars composed of the same parental species. However, the syn2 of LMFA did not show an improved drought tolerance during a dry growing season compared to other Festulolium cultivars, and the seed yield of LMFA syn1 was low and dropped extremely in syn2. The number of chromosomes of LMFA also decreased gradually from F1 to syn2, and there was a clear shift in chromosome composition towards the Lolium genome. The LPFP synthetic performed better. Although the sugar content was significantly lower than the sugar content of the perennial ryegrass cultivars, organic matter digestibility (OMD) of LPFP was as high as OMD of the tetraploid perennial ryegrass cultivars. The cell wall digestibility (NDFD) of LPFP was significantly higher than the NDFD of both parental species and higher than the NDFD of all tested Festulolium cultivars. The seed yield of LPFP was the same in syn1 and syn2. The chromosome number remained on average the same and no clear shift of the chromosome composition to one of the composing genomes was observed. Overall, chromosome analysis revealed a high number of aneuploidy in syn1 and syn2 generations of both LMFA and LPFP and a lot of variation in number of Lolium, Festuca and recombinant chromosomes, and in the Lolium:Festuca genome ratio was observed among different genotypes of the same population. Therefore, selection for genotypes with a more stable genome composition will be a prerequisite for a sufficient seed yield and a broader exploitation of these new Festulolium synthetics.

The microRNA319 (miR319) family is involved in plant development and responses to abiotic stresses. Previous work showed that miR319 responded to chilling stress in the chilling-tolerant wild tomato (Solanum habrochaites L.) genotype LA1777. Here, the precursors of sha-miR319a, b, c, and d were cloned from LA1777 and the putative target genes tosinte branched/cycloidea/proliferating cell factors (TCP3 and TCP29) were validated using 5′-RLM-RACE. Expression patterns revealed a negative correlation of sha-miR319 with TCP3 and TCP29 in LA1777. Four tomato (S. lycopersicum) genotypes with varying sensitivities to chilling and heat stresses were selected to characterize expression patterns of miR319 and target genes under extreme temperatures. The involvement of miR319 in the chilling tolerance of tomato might be mediated by the repression of TCP3 and TCP29 expression. Initial stages of heat stress resulted in the up-regulation of miR319a, b, and d and led to a decrease in TCP3, TCP29, and TCP2 expression, whereas the down-regulation of miR319c in the later stages of heat stress may have been responsible for the subsequent up-regulation of TCP3, TCP29, and TCP2. Cis-elements found in the promoter regions of the miR319 family members indicated a potential role of miR319 in the regulation of stress tolerance and development processes. This study provides insights into the role of miR319-mediated regulatory mechanisms in responses to temperature stress in tomato genotypes.

The miR399 is a conserved microRNA (miRNA) family, and it has been characterized as an essential regulator of phosphorus transport in plants. However, the biological function of miR399 in Cunninghamia lanceolata is still largely unclear. In this study, the comparison of mature miR399 sequence revealed a high similarity between Arabidopsis thaliana and C. lanceolate, and the pre-miR399 was capable of forming a typical stem-loop hairpin structure. A gene PHOSPHATE 2 (PHO2) was identified as a target of cln-miR399 using 5' rapid amplification of cDNA ends. Furthermore, the relationship between cln-miR399 and PHO2 was further confirmed through a transient co-expression of both genes in Nicotiana benthamiana. To examine the function of miR399 in Arabidopsis, miR399-overexpressing transgenic Arabidopsis thaliana was acquired using Agrobacterium-mediated approach. Real-time PCR showed that the amount of cln-MIR399 transcripts was higher in miR399-overexpressing plants than in wild-type plants, which was accompanied with down-regulation of expression of its target gene AtPHO2. The P content was 1.40 to 1.56-fold higher in the leaves of three transgenic lines than in wild type plants. However, the P content in the roots of the three transgenic lines was 24.5 - 37.2 % less than that in wild type plants. Moreover, the transcriptions of three phosphate transporter genes (PHT1, PHT2, and PHT3) were up-regulated in roots of miR399-overexpressing Arabidopsis plants. Interestingly, the transgenic lines exhibited retarded growth under normal P conditions compared with the wild type. Our findings demonstrate that cln-miR399 may play crucial roles in P transport and plant growth via regulation of its target gene PHO2.

Plasmodiophora brassicae is a biotrophic pathogen causing clubroots of cruciferous crops. The Brassica rapa accession T1-145 has an ability to produce small spheroid galls (SSGs), which represent neither a fully compatible interaction nor a complete resistance. To explore the defense response in SSGs induced by P. brassicae infection, global transcriptome profiling SSGs was performed at different time points. By comparing gene expression patterns, we identified many defense related genes. The first group included genes encoding receptor-like protein/kinases, such as cysteine-rich receptor-like protein kinases, receptor-like proteins, phloem intercalated with xylem/tracheary element differentiation inhibitory factor receptor (PXY/TDR), PXY-correlated 1, wall-associated kinases, nuclear shuttle protein-interacting kinase, lectin receptor-like kinases, and flagelin-sensitive 2, which might activate a basal defense. The second group involved robust effector-triggered immunity response genes such as resistance to leptosphaeria maculans 1B, constitutive shade-avoidance 1, target of avirulence B operation 1, ribosomal protein of the small subunit 6, resistance to Pseudomonas maculicola 1-interacting protein 4, enhanced disease resistance 2L, and recognition of Peronospora parasitica 13-like protein 4. The third group included genes encoding secondary cell wall formation related protein/s, a nodulin-like protein, a germin-like protein, a jacalin-related lectin, a defensin-like protein, tumor inhibitors, and sugars will eventually be exported transporter, which might contribute to quantitative resistance against P. brassicae. The gene expressions were the highest at the late stage of infection. To our knowledge, it is the first report on exploring defense response genes during SSG occurrence by a transcriptome analysis. Our data would provide useful information to further explore molecular mechanisms of the incomplete resistance.

Several studies revealed the important contribution of calcineurin B-like (CBLs) and CBL-interacting kinase (CIPKs) genes in transmitting stress signals in plants. Taking advantage from the genome sequences of the cultivated potato Solanum tuberosum and its wild relatives S. commersonii and S. chacoense, we identified for the first time 10 CBLs and 26 CIPKs genes in each species. The CBLs and CIPKs derived from tandem duplications indicate that these gene families in potato mainly arise through amplification mechanisms. Once annotated, we compared the par excellence model of Arabidopsis thaliana with S. commersonii, the potato model species for studying cold tolerance. We found that four ScCBL proteins (ScCBL1, ScCBL4a, ScCBL4b, and ScCBL9) started with a conserved N-myristoylation motif (MGXXXS/T), which might function in membrane targeting of the CBLs-CIPKs complex. Additionally, expression analyses of S. commersonii CBL and CIPK genes based on RNAseq revealed diverse expression patterns following various abiotic and biotic stresses and in the four tissues analyzed (flowers, leaf, roots, and tubers). Data also suggest that the ScCBLs-ScCIPKs complex may be more responsive to abiotic rather than biotic stimuli. Overall, the results described in the present work will be useful for future investigations and for functional characterization of individual CBLs and CIPKs in Solanum.

To further elucidate the molecular mechanism of the germination in common wheat, a differential proteomic analysis was completed between the F₁ hybrid RS5322 and its parental lines (RS53 and SN22) using isobaric tags for relative and absolute quantitation (iTRAQ) based strategy. Rapid grain germination and superior young seedling growth were observed in the F₁ hybrid line. A total of 807 differentially abundant proteins (DAPs) were identified by iTRAQ analysis of grains at 48 h after imbibition in distilled water. Bioinformatics analysis shows that 638 DAPs were annotated in 38 Gene Ontology functional groups, 764 DAPs were classified into 23 clusters of orthologous groups of protein categories, and 538 DAPs were enriched in 65 Kyoto encyclopedia of genes and genomes pathways. Real time quantitative PCR of 12 genes encoding different important proteins showed certain transcriptional and translational expression similarities during grain development. In the F₁ hybrid, the DAPs were particularly those involved in starch and sugar metabolism, protein metabolism, protein modification, and ubiquitin proteasome system (UPS). It was speculated that UPS might be responsible for a high germination ability in the F₁ hybrid by regulating storage substance metabolism. The DAPs identified in this study provide a scope for improving the grain germination trait in agricultural crops.

Flood in rice fields at the time of seed sowing and early seedling establishment causes extensive crop loss due to the inability of the seeds to tolerate and overcome submergence. In the present study, rice genotypes from Assam, India tolerant to hypoxia during germination were identified through systematic screening of deep-water rice genotype collection from flood-prone ecosystem of Brahmaputra river valley. The difference in tolerance to hypoxia during germination within the species provides scope for identification of novel hypoxia-responsive factors involved in tolerance as mechanism of tolerance may not be conserved across tolerant germplasms. Tolerant genotypes were further subjected to physiological and molecular characterization. Growth rate kinetics in tolerant genotypes new Rangdhakekua bao (RKB) and cultivar Khao Hlan On (KHO) from International Rice Research Institute (IRRI) used as positive control exhibited stronger escape strategy under hypoxic condition compared to sensitive genotype IR-64 (negative control). Activities of α-amylase and pyruvate decarboxylase were significantly higher in RKB and KHO than in IR-64, while no significant difference was observed in the alcohol dehydrogenase activity. Reverse transcription quantitative PCR confirmed increased amounts of transcripts of sucrose nonfermenting 1 related protein kinase, myeloblastosis-related protein S1, rice amylase 3D, and trehalose phosphate phosphatase 7 genes, which are known to be involved in hypoxia signaling cascade. Besides, transcription factors (TFs) like ethylene responce factors 71 and 63, ethylene insensitive 3-like 1a and proteins like expansins A7 and A2, which are involved in cell elongation had also significantly higher amounts in RKB compared to IR-64. Additional factors that include TFs like ERF71 and ERF63 that shows perturbation at transcription even within tolerant genotypes might constitute the genotype-specific regulation, evolved as a part of its adaptive mechanism to survive under submerged conditions.