The tubular ray flower (turf) mutant of sunflower is characterized by a switch of ray flowers from zygomorphic to near-actinomorphic disc flowers. In sunflower, floral symmetry of ray and disc flowers is specified by the activity of members of a CYCLOIDEA (CYC) gene family. The turf mutant is generated by the insertion of a CACTA-like transposable element (TE), named Transposable element of turf1 (Tetu1), in the coding sequence of the HaCYC2c gene. The TEinsertion changes the reading frame of turf-HaCYC2c for the encoded protein and leads to a premature stop codon. Tetu1 is a non-autonomous version of a CACTA TEcarrying the minimum sequences necessary for transposition in the presence of autonomous elements in the sunflower genome. In the previous analysis, performed in more than 11 000 plants homozygous for the turf-HaCYC2c allele, the absence of chimerism and the segregation rate of derived-progenies from reverted phenotypes suggest that Tetu1 transpositions are restricted to a time shortly before and/or during meiosis. Here, we report the analysis of F₅ and F₆ progenies, derived from an F₄ progeny of the cross turf × Chrysanthemoides2, where plants with a chimeric inflorescence were detected. Tetu1 showed active excision in all progenies taken into consideration and named High Frequency of Tetu1 Transposition (HFTT). Within a total of 449 plants, Tetu1 excision generated a 13.81 % of non-chimeric revertants but also a 5.12 % of plants with somatic sectors of variable size in the outmost whorl of the inflorescence. These unexpected results suggest variations in tissue specificity and time of TEexcision. The excision of Tetu1 was confirmed by DNA molecular screening of non-chimeric and chimeric revertants and transcription analysis of the HaCYC2c gene. In HFTT progenies, sequence analyses excluded significant DNA changes with respect to the original Tetu1 transposon as well as to the adjacent 5'- and 3'-TE regions. Genetic and epigenetic regulatory mechanisms were proposed to explain the time and frequency of Tetu1 transposition in HFTT progenies.

To reveal the physiological and biochemical mechanism underlying graft union formation in pecan (Carya illinoinensis), dynamic changes in content of nutrients, tannin, and phytohormones together with key enzyme activities were investigated 0, 3, 5, 7, 10, 14, 18, 22, 31, and 40 d after grafting (DAG), in homograft unions. During graft union formation, peroxidase (POD) activity increased at 7 - 10 DAG compared with that at 0 DAG. Polyphenol oxidase (PPO) activity was higher in grafted than ungrafted pecan seedlings (control) at 22 DAG, which was similar to POD activity. The tannin content exhibited a decreasing trend with grafting relative to the control. Indole-3-acetic acid (IAA) and zeatin riboside (ZR) content increased from 7 - 10 DAG, with higher average content than in the control at 14 - 31 DAG. Abscisic acid (ABA), soluble sugar, starch, and soluble protein content was generally lower in grafted plants than in the control. Combined with our previous anatomical observations, these results suggested that, during graft development, some enzymes and growth promoting hormones might be required for callus proliferation at early stage and for vascular reconnection at the later stage. Nutrients provided energy for the whole graft development process. In contrast, some polyphenols and growth inhibiting hormones seemed to have negative effects on this process.

Tomato yellow leaf curl virus (TYLCV), a whitefly-transmitted single-stranded DNA (ssDNA) virus, causes the most important viral disease of tomato worldwide. TYLCV-mediated disease is mainly controlled via extensive insecticide sprays aiming at the whitefly vector. RNA-based vaccination was proven to be a non-transgenic approach leading to efficient plant virus control. In this work, double-stranded RNA (dsRNA) molecules deriving from sequences of the C4 and V2 genes of TYLCV-Mild were produced in vitro and topically applied onto tomato plants along with the virus (via agroinfiltration). DsC4 and dsV2 application reduced disease incidence to 23 and 46 %, respectively, while TYLCV positive control reached 64 %. Bioinformatics analysis of the virus-specific small interfering RNAs (vsiRNAs) from TYLCV-infected tomato revealed 'hot' and 'cold' spots in the TYLCV-Mild genome. Interestingly, the viral C-strand had twofold siRNA reads when compared to that of the V-strand. Overall, vsiRNAs of negative and positive polarity were almost equal (53.5 vs. 46.6 %); vsiRNAs of negative polarity prevailed at the V-strand. Stem-loop RT-PCR validated the presence of six vsiRNAs (hot or cold spots) in TYLCV-Mild-infected and dsRNA-treated tomato. The exogenously applied dsRNA was found to rapidly move systemically in tomato and was detected for 54 days post treatment (dpt). The applied dsRNA molecules were successfully processed by the Dicer-like proteins (DCLs) in tomato since small interfering RNAs (siRNAs) deriving from the dsRNA were detected for at least 54 dpt. This consists the first report of dsRNA-based vaccination applied against a monopartite geminivirus.

The myeloblastosis (MYB) transcription factors are essential for plant stress responses. They can enhance plant tolerance to abiotic stresses (e.g., drought, salinity, and cold) via improved physiological and biochemical responses including the accumulation of metabolites. In this study, we constructed a Panax ginseng MYB4 (PgMYB4) gene expression vector and established the stable transgenic Arabidopsis thaliana lines to study the effects of this gene on plant stress tolerance. The germination rate and seedling taproot length were greater for the PgMYB4-overexpressing plants than for the wild-type plants. Accordingly, the overexpression of PgMYB4 in Arabidopsis enhanced seedling tolerance to drought, salt, and cold conditions. Under drought stress, the relative chlorophyll content decreased less, the proline content increased more, and the water loss rate decreased more in the transgenic plants than in the wild type. The expressions of stress-related genes responsive to dehydration 19A, responsive to dehydration 22, responsive to desiccation 29A, cold-regulated 15A, cold-regulated 47, and pyrroline-5-carboxylate synthase 1 were significantly upregulated in the transgenic Arabidopsis plants. Under high salt stress, the kinesin 1 (KIN1) expression was significantly upregulated in the transgenic plants. In response to the low temperature stress, the dehydration-responsive element binding protein 2A and KIN1 expressions increased dramatically in the transgenic Arabidopsis plants. Thus, PgMYB4 positively regulated the stress tolerance gene networks, which promoted the expression of anti-stress effector genes. This gene may be useful for ginseng breeding programs aiming to develop new cultivars with enhanced stress tolerance.

According to the survey, wild purslane (Portulaca oleracea L.) has two different ecotypes, one with the red stem living in an arid environment and one with the green stem living in a humid environment. In order to explore the physiological response strategies of plants to environmental changes, these two ecotypes of purslane were selected as experimental materials. Physiological indices were determined and transcriptome analysis was carried out to screen the differentially expressed genes (DEGs) from two ecotypes of purslane. The results showed that the content of soluble sugars, proline, anthocyanins, and chlorophylls was significantly different, and most DEGs belonged to the WRKY and NAC families. Finally, the results of transcriptome analysis were verified by real-time qPCR. Therefore, it can be inferred that the transcription factor (TF) families may play an important role in physiological response strategies by regulating the changes of anthocyanins and osmotic regulators (soluble sugars, proline, etc.) through the abscisic acid signalling pathway. This will accelerate the study of purslane at the molecular level, provide corresponding theoretical support for its artificial domestication, and drought breeding.

The importance of Na⁺/H⁺ antiporters in salt tolerance in plants has been demonstrated in many studies, but much less is known about their protective role during drought stress. To study their possible contribution to water deficit tolerance, two closely related soybean Na⁺/H⁺ antiporters belonging to the intracellular NHX exchanger protein family, GmNHX3 and GmNHX1, were evaluated in transgenic Arabidopsis thaliana. A. thaliana plants ectopically expressing GmNHX3 or GmNHX1 displayed a more drought-tolerant phenotype compared to wild-type plants, which was accompanied by an increase in relative water content and chlorophyll content during stress conditions. Both GmHNX1 and GmHNX3 transgenic lines accumulated higher amounts of Na⁺ and K⁺ cations, showed increased antioxidant enzyme activities and less membrane damage due to lipid peroxidation under water deficit, as compared to non-transformed plants. Furthermore, plants expressing GmNHX3 showed an increased sensitivity to abscisic acid as deduced from stomatal closure and seed germination inhibition studies. Finally, a significant up-regulation of abiotic stress-related genes was observed in both transgenic lines compared to wild-type plants in response to abscisic acid and mannitol treatments. These results demonstrate that GmNHX3 and GmNHX1 antiporters confer protection during drought stress in A. thaliana and hence are potential genetic targets to improve drought tolerance in soybean and other crops.

Thioredoxins are oxidoreductases that help to maintain redox homeostasis in plants under abiotic stress. In this study, a new thioredoxin gene, SikTrxh, was cloned from Saussurea involucrata (Kar. & Kir.), a perennial herb that grows in the high alpine mountains of Central Asia. Bioinformatics analysis shows that the full-length cDNA of SikTrxh consisted of 565 bp with a 354-bp open reading frame and encoded a 117 amino acid protein. Using quantitative reverse transcription (RT) PCR, we found that the expression of the SikTrxh gene was induced by salt, cold, and drought stresses, suggesting that this protein played a significant role in plant defense. Subcellular localization confirmed that the protein was localized to the mitochondria. A vector carrying SikTrxh was inserted into tobacco, and successfully modified plants were identified by RT-PCR. Physiological indicators and antioxidant enzyme activities were measured under low temperature, and salt and drought stresses. Our results show that malondialdehyde content and relative electrolyte leakage increased in both wild-type and SikTrxh-overexpressing transgenic plants; however, these increases were significantly higher in the wild-type plants than in the transgenic plants. We also found that photosystem II photoinhibition was lower in the transgenic plants than in the wild-type plants, and that activities of reactive oxygen species-scavenging enzymes were higher in the transgenic plants than in the wild-type plants. We conclude that SikTrxh can reduce toxic effects of reactive oxygen species to protect the plasma membrane, thereby increasing plant resistance to abiotic stresses.

Nucleotides are the basic elements of the genetic material, participate in bio-energetic processes, are cofactors and components of secondary metabolites, etc. Nucleotide hydrolases (nucleotidases) are phosphatases that remove the 5'-phosphate group from the nucleotides and play a crucial role in nucleotide metabolism. In this study, genes encoding putative nucleotidases in Phaseolus vulgaris have been identified, and the effect of methyl jasmonate (MeJA) on both nucleotidase activity and gene expression has been addressed. The predicted nucleotidase peptides include the conserved domains characteristic of the haloacid dehalogenase-like hydrolase superfamily. The analysis of the expression of the 11 identified genes in radicles of common bean seedlings elicited with MeJA showed that 3 of them are highly induced by this phytohormone in a dose-dependent manner. Nucleotidase activity in radicles from MeJA treated plants was higher than in not elicited seedlings, and this induction was observed with all the nucleotides assayed (mono-, di- or triphosphate) and with purine or pyrimidine nucleotides. MeJA is involved in biotic and abiotic stress, and the induction of nucleotide metabolism in response to this treatment suggests a relevant role for nucleotides in the seedlings response to unfavourable conditions.

Rapid propagation of plants by tissue culture is of great significance for large-scale production, molecular genetics research, and breeding. Currently, a rapid and high-efficient tissue culture protocol for Euonymus bungeanus is needed. To develop a propagation system for this species, we established a new regeneration system from leaves. Callus formation was induced on Murashige and Skoog (MS) medium supplemented with 0.5 mg dm^-3 6-benzylaminopurine (6-BA) and 0.5 mg dm^-3 α-naphthalene acetic acid (NAA) and the induction rate almost reached 100 % under red radiation within 21 d. The medium for proliferation of adventitious buds comprised of MS medium with 1.0 mg dm^-3 6-BA and 0.5 mg dm^-3 NAA, and the induction rate within 20 d nearly reached 100 %. When, the adventitious buds were transferred to the rooting medium containing 1/2MS, 2.0 mg dm^-3 indole-3-butyric acid (IBA), and 0.05 mg dm^-3 NAA, adventitious root formation was achieved within 20 d. Collectively, the rapid and high-efficient regeneration system from E. bungeanus leaves was established, providing useful references for effective mass propagation and it could serve as an enabling technology for future genetic engineering.

Ricinoleic acid is a kind of unsaturated fatty acids in oil of castor bean (Ricinus communis) seeds with wide application value. However, there is little transcriptomic information on genes related to ricinoleic acid biosynthesis in castor beans. To better understand the regulation mechanism of ricinoleic acid biosynthesis, immature seeds at three developmental stages (S1, S2, and S3 corresponding to 15, 30, and 45 d after pollination) were collected. The results indicated that the accumulation of castor bean oil and ricinoleic acid increased gradually during seed development, and reached the maximum value at the late stages of seed development (45 d after pollination). Furthermore, RNA sequencing was conducted to analyze the transcriptome of the developing seeds at three developmental stages. Totals of 9 875 differentially expressed genes (DEGs) were identified among the three time points. Based on the annotation information, 49 DEGs related to lipid biosynthesis were screened among all DEGs. Through cluster analysis of the 49 DEGs, ten genes with increasing FPKM values from seed development stages S1 to S3 were selected as candidate key enzymes, since they showed similar patterns of increase with castor bean oil accumulation and ricinoleic acid biosynthesis during seed development. The transcriptomic data of the 10 candidate key enzyme genes was further validated by RT-qPCR. Ultimately, a putative model of key genes correlated with ricinoleic acid accumulation was built. Our study identified a series of key genes and revealed the proposed molecular mechanism of ricinoleic acid accumulation in castor bean seeds through the transcriptional analysis. It broadens our knowledge of ricinoleic acid biosynthesis and castor bean oil accumulation and also provides a theoretical foundation for the genetic engineering key genes that can improve the ricinoleic acid production in castor beans as well as in other plants.

A cDNA encoding γ-tocopherol methyltransferase from Brassica napus (BnTMT) was overexpressed in soybean [Glycine max (L.) Merr.] under the control of seed-specific promoter of Arabidopsis fatty acid elongase 1 (FAE1) or soybean glycinin G1. Two and three transgenic plants were selected, respectively, after Agrobacterium-mediated transformation. Polymerase chain reaction (PCR) and Southern blots confirmed that BnTMT was single-copy integrated into the genome of transgenic plants. RT-PCR analysis showed that the expression of BnTMT was higher in the immature cotyledons than in the mature cotyledons, while no expression was detected in the leaves. Moreover, the expression level under the control of FAE1 was higher than that of G1. HPLC analysis indicated that the seed-specific expression of BnTMT resulted in 11.1-fold and 18.9-fold increase in α- and β-tocopherol content, respectively, in T₂ seed. These results suggested that introducing BnTMT into soybean can be used to increase the vitamin E composition in seeds.

MRCTLH (muskelin/RanBPM/CTLH) is a protein complex found in humans (MRCTLH) that is involved in the regulation of numerous cellular processes, such as gluconeogenesis, cell signaling, development, nuclear extrusion, cell morphology, or stability of different proteins. According to genomic data, all eukaryotes have similar protein complexes. In yeast, a similar protein complex named GID was found to be involved in the regulation of gluconeogenesis. LICC1 is a maize protein whose sequence resembles that of TWA1 in humans and GID8 in yeast, which are central components of the MRCTLH and GID complexes. LICC1 contains three highly conserved protein domains, LisH, CTLH, and CRA, typical of this protein family. Twa1 and gid8 are unique genes in human and yeast genomes. However, three copies of licc1 are present in the maize genome and multiple copies are present in other plant genomes. This result suggests the presence of multiple variants of the MRCTLH/GID complex in plants, which could increase its regulatory capacity. We also demonstrate here that LICC1 has the ability to interact with microtubules, similarly to the human TWA1. This interaction reinforces the idea that the LICC1 protein from maize, and its homologues in plants and, in general, the GID/MRCTLH complex in plants, can perform biological functions similar to those in humans and yeast.

Salinity has a huge negative impact on plant growth and development by increasing sodium ions accumulation and potassium ions loss that deeply disturbs the plant cell homeostasis and can lead to plant cell death. The imbalance between Na⁺ and K⁺ could be solved by applying potassium silicate (K₂SiO₃). The glycine betaine (GB) is well-known to play a crucial role against oxidative stress in plants by improving the antioxidant machinery. Thus, this research aimed to apply K₂SiO₃ (1 mM) and GB (10 mM) alone or in combination against 200 mM NaCl-induced damages in Dalbergia odorifera. The results showed a significant amelioration of negative effects of salt stress on the phenotypic traits, chlorophyll content, net photosynthetic rate, stomatal conductance, transpiration rate, and water use efficiency by applied substances. The contents of saccharides and proline were down-regulated by K₂SiO₃, GB, and K₂SiO₃-GB, whereas the proteins content was increased by these treatments. The contents of lipid peroxidation, superoxide anion, hydrogen peroxide were reduced by exogenous substances under stress. The activities of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) and the accumulation of antioxidants (glutathione and ascorbate) were enhanced by exogenous substances. The K₂SiO₃-GB combination mostly showed better effects on antioxidant machinery compared to a single treatment.

Spermine (SPM) is involved in response to abiotic stress in plants, but the potential role of SPM in regulating senescence has not been well documented. Objectives of this study were to examine the effect of changes in endogenous polyamines (PAs) by SPM application on improving heat tolerance of creeping bentgrass (Agrostis stolonifera) and explore the SPM-regulated senescence associated with alterations of water and oxidative balance, photosynthesis, and heat shock proteins under heat stress. The results showed that persistent high temperature caused severe oxidative damage and significant decreases in chlorophyll (Chl) content, photosynthetic efficiency, and leaf water content leading to premature senescence in creeping bentgrass, as reflected by a significant upregulation of transcriptions of senescence-associated genes (AsSAG39, Ash36, and Asl20). The improvement of endogenous spermidine (SPD) and SPM content induced by SPM application could significantly alleviate heat stress damage to creeping bentgrass through maintaining higher Chl content, net photosynthetic rate, photochemical efficiency, and performance index on absorption basis, promoting osmotic adjustment ability and antioxidant enzyme (superoxid dismutase, catalase, peroxidase, and ascorbate peroxidase) activities to enhance the scavenging capacity of reactive oxygen species, and upregulating transcriptions of heat shock protein (HSP) genes (HSP90-5, HSP90.1-b1, HSP82, HSP70, HSP26.7, HSP17.8, and HSP12) helping to maintain normal synthesis and functions of proteins under high temperature stress, thereby delaying heat-induced leaf senescence. These findings reveal an important role of PAs in regulating senescence in perennial plants exposed to a high temperature environment.

Vetiver grass [Vetiveria zizanioides (L.) Nash] displays comprehensive abiotic stress tolerance closely related to fine maintenance of plant water relation mediated by plasma membrane intrinsic proteins (PIPs). Two open reading frame sequences of PIPs (867 and 873 bp) were cloned from vetiver grass and named as VzPIP1;1 and VzPIP2;1, respectively. Expression of green fluorescent protein revealed only subcellular localization of VzPIP2;1 in the plasma membrane. Agrobacterium tumefaciens mediated transgenic (VzPIP2;1) soybean plants had a higher water content in above-ground parts under sufficient water supply through enhancing transpiration as compared to the non-transgenic plants but displayed a more severe drought injury because of a lower photosynthesis and a higher transpiration rate. However, A. rhizogenes mediated transgenic soybean plants kept a higher water content in above-ground parts by improving root water transport and kept a more effective photosynthesis under normal and drought conditions.

Abiotic stresses strongly impair plant development and might impose detrimental effects particularly on seedlings. Irradiance and water deficit are relevant factors, which affect performance of young plants under controlled conditions. In our study, we investigated the influence of water shortage combined with different radiation sources - light emitting diodes (LED) and compact fluorescence lamps (CFL) - on physiological and biochemical parameters of young apple plants. Stress responses were assessed by fluorescence-based indices, while relative water, chlorophyll (Chl), and proline content served as reference parameters. The watering regime had a higher impact on biochemical indicators than the radiation sources. Lower Chl content was determined in plants grown under LED both in control and in water deficit plants. Nitrogen balance index and nitrogen balance index with red radiation excitation showed similar patterns regarding leaf Chl results in relation to the radiation source, being higher under CFL. In contrast, the flavonol index was higher in plants cultivated under LED. Stomatal conductance and maximal photochemical efficiency emphasised a radiation quality effect with higher values for CFL. In conclusion, fluorescence indices related to nitrogen status and flavonol content are promising parameters to sense physiological impairments under the given conditions. However, discrepancies compared to previous studies might be related to the different plant species, the nature of dehydration, and the measuring conditions.

Chlorophyllases (Chlases) are housekeeping proteins in plant cells. The dephytylating enzymes can catalyze chlorophyll (Chl) to form chlorophyllide, but the distribution of Chlases in plant cells is still an interesting debate. Previously, we showed that PmCLH2 was a nuclear-encoded gene, and PmCLH2 protein was located in cytosol and chloroplasts of Pachira macrocarpa (Pm). In this study, the antibody of PmCLH2 was made and used by the immunogold-labelling technique to detect the localization of Chlase of Pm leaves at four developmental stages (young, mature, yellowing, and senescent). The transmission electron microscopy results show that Chlases were comprehensively found in parts of the chloroplast, such as the inner membrane of the envelope, grana, and the thylakoid membrane as well as in cytosol, and vacuoles at young, mature, and yellowing stages of Pm leaves, but not in the cell wall, plasma membrane, mitochondria, and nucleus. In short, PmCLH2 was mainly detected in vacuoles at the senescent stage, but a few were found in the chloroplasts. A pathway is proposed to explain the birth and death of Chl, Chlase, and chloroplasts in higher plants.

Mechanisms of drought tolerance have been studied by numerous groups, and a broad range of molecules have been identified to play important roles. A noteworthy response of stressed plants is the accumulation of novel protective proteins, including heat-shock proteins (HSPs) and late embryogenesis abundant (LEA) proteins. Identification of gene regulatory networks of these protective proteins in plants will allow a wide application of biotechnology for enhancement of drought tolerance and adaptation. Similarly, aquaporins are involved in the regulation of water transport, particularly under abiotic stresses. The molecular and functional characterization of protective proteins and aquaporins has revealed the significance of their regulation in response to abiotic stresses. Herein, we highlight new findings regarding the action mechanisms of these proteins. Finally, this review also surveys the current advances in engineering drought tolerant plants, particularly the engineering of protective proteins (sHSPs and LEA) and aquaporins for imparting drought stress tolerance in plants.

Agricultural production worldwide has been severely impacted by cold and freezing stresses. Plant capacity to acclimate to environmental conditions in their immediate vicinity largely control their survival, growth, and productivity. Molecular as well as biochemical mechanisms underpinning plant cold acclimation are very complex and interwoven. The cold-impacted plants try to modulate expression of variety genes controlling cell membrane lipid composition, mitogen-activated protein kinase cascade, total soluble proteins, polyamines, glycinebetaine, proline, reactive oxygen species (ROS) scavengers, cryoprotectants, and a large number of cold responsive factors. To this end, this paper dissects the array of transcriptional factors/genes down- or up-regulated, their identification in different plant species, recognition of cold tolerant/resistant transgenic plants, complexity of the mitogen-activated protein kinase cascade, as well as their cross talk under different stresses and molecular mechanisms. Furthermore, it also comprehensively elucidates physio-biochemical interferences in cold acclimation with a particular emphasis on endogenous content as well as exogenously supplied different types of polyamines, ROS, and osmoprotectants. Overall, low temperature stress tolerance or cold acclimation varies greatly among species depending on the stress intensity and duration and type of plant species.

Development of transgenic plants by introducing defense genes is one of the strategies to engineer disease resistance. Transgenic ASD16 rice plants harbouring rice chitinase chi11 gene, belonging to a PR-3 group of defense gene conferring sheath blight (Rhizoctonia solani Kuhn) resistance, were used in this study. Three T₂ homozygous lines (ASD16-4-1-1, 5-1-1, and 6-1-1) were identified from seven putative (T₀) transgenic lines expressing chi11 using Western blotting analysis. The inheritance of sheath blight resistance in those lines was studied over generations. The stability of chi11 expression up to T₄ generation in all the three homozygous lines was proved by Western blot and the stability of sheath blight resistance in the homozygous lines was proved up to T₄ generation using detached leaf and intact leaf sheath assays. Among the three homozygous lines tested, ASD16-4-1-1 showed consistent results in all the generations and gave a better protection against the sheath blight pathogen than the other two lines.

In plants, many C2H2-type zinc finger transcription factors function in plant defense responses to biotic and abiotic stresses. Here, we report cloning and characterization of VvZFP11 which encoded a C2H2-type zinc finger protein (ZFP) in grapevine (Vitis vinifera). Sequence analysis shows that VvZFP11 contained one L-box, two C2H2-type zinc finger motifs and one ERF-associated amphiphilic repression (EAR) motif. The VvZFP11 localized to the nucleus and functional analysis shows that full-length VvZFP11 had no transcriptional activity, but VvZFP11 lacking the EAR motif had a strong transcriptional activity in yeast. In grapevine, expression of VvZFP11 was induced by salicylic acid and methyl jasmonate and also quickly responded to infection with Erisiphe necator. Arabidopsis thaliana plants overexpressing VvZFP11 were more resistant to Golovinomyces cichoracearum, and real time quantitative polymerase chain reaction revealed that defense-related genes AtPR1 and AtPDF1.2 were up-regulated in the overexpressing lines. These results suggest that VvZFP11 might play an important role in defense responses in grapevine.

We previously reported that LeMYB1 might be a crucial transcription factor in regulating shikonin formation in Lithospermum erythrorhizon. In this study, by overexpressing LeMYB1 under the control of CaMV35S promoter in L. erythrorhizon hairy roots, we further clarified the role of LeMYB1 in the shikonin formation and its regulation. The LeMYB1-overexpressing transgenic hairy roots were successfully induced by infecting seedling nodes with Agrobacterium rhizogenes strain ATCC15834 that carried the pBI121-LeMYB1 vector. The LeMYB1 transcripts were significantly up-regulated in the transgenic hairy root lines compared with the wild type lines, and the total content of shikonin and its derivatives was dramatically enhanced by the LeMYB1 overexpression. Real-time PCR results reveal that the enhanced shikonin biosynthesis in the overexpressing lines were mainly caused by a highly up-regulated expression of genes coding key enzymes (PAL, HMGR, and PGT) and key regulators (LeDI-2 and LePS-2) involved in the shikonin biosynthesis. Overall, our results suggest that LeMYB1 plays a positive role in regulating the shikonin biosynthesis in L. erythrorhizon.

The gene FRIGIDA (FRI) is floral repressor and plays a key role in the timing of Arabidopsis flowering. To study the function of FRI-like genes in bamboo, we isolated a FRI family gene from bamboo Phyllostachys violascens and named it PvFRI-L. Sequence alignment and phylogenetic analysis show that the PvFRI-L protein belongs to the FRL3 (III) subfamily from monocots and contains a conserved FRIGIDA domain. PvFRI-L was located in the nucleus of onion epidermal cells. PvFRI-L was expressed in all tested organs of flowering and non-flowering bamboo plants with a higher expression in non-flowering than in flowering plants. Overexpression of PvFRI-L in Arabidopsis caused late flowering by downregulating flowering locus T and upregulating flowering locus C. A P-box, the binding site involved in gibberellin response, was found only in the promoter region of PvFRI-L but not in that of FRI. Furthermore, PvFRI-L expression in the leaves of Ph. violascens seedlings was downregulated with gibberellic acid treatment. Taking together, our observation suggests that PvFRI-L may be flowering repressor and its delaying floral timing may be regulated by gibberellic acid in bamboo.

Na⁺/H⁺ exchanger (NHX)-mediated Na⁺ and H⁺ antiport is an important mechanism for salt tolerance in plants. In this study, an Na⁺/H⁺ antiporter gene, referred to as NsNHX1, was isolated from the halophyte Nitraria sibirica Pall. using degenerate polymerase chain reaction (PCR) and rapid amplification of cDNA ends (RACE). The resulting 2 182 bp NsNHX1 cDNA contained a 1 635 bp open reading frame (ORF) that encoded 544 amino acids and showed striking sequence similarity to tonoplast-localized NHXs from other plants. Subcellular localization analysis confirmed NsNHX1 to be a tonoplast-localized protein. Cis-elements described as being responsive to biotic and abiotic stresses were present in the NsNHX1 promoter region, and reverse transcription (RT)-PCR analysis confirmed that NsNHX1 expression was induced by exogenous abscisic acid (ABA), cold, and NaCl. Transcription of NsNHX1 increased sharply 3 h after treatment with 200 mM NaCl revealing that NsNHX1 responded rapidly to the salt stress. Overexpression of NsNHX1 enhanced salt tolerance in transgenic Arabidopsis thalliana L. suggesting that NsNHX1-mediated Na⁺ compartmentalization played an important role in enhancing plant salt tolerance.

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.

Glandular trichomes, a specialized multicellular structure, are considered as biofactories due to their capability to synthesize and secrete a large amount of secondary metabolites. Tobacco leaves have a high density of glandular trichomes that produce huge amounts of secondary metabolites, which can be used as important industrial raw materials. However, molecular mechanism controling glandular trichome development in tobacco still remains largely unknown. In the present study, we found that NbGL3, an HD-Zip IV family gene from Nicotiana benthamiana, was highly expressed in mature leaves, and ethylene or auxin application could increase the expression of NbGL3. Virus induced gene silencing NbGL3 resulted in a decreased glandular trichome density on leaves. Putative downstream genes, such as micro trichome, cyclin B2, and wax inducer 1 like were down regulated in NbGL3 silenced plants. Our results demonstrate that NbGL3 could positively regulate initiation of glandular trichomes in tobacco.

Strelitzia reginae is a popular cut flower that has blue petals and orange sepals. Flower color is an important plant trait; however, little is known about its molecular mechanisms in S. reginae. In this study, cDNA libraries were constructed for blue petals and orange sepals of S. reginae. A total of 75 487 unigenes were obtained from transcriptome sequencing and de novo assembly, of which 41.86 % were annotated by public databases. Ultra-high performance liquid chromatography analysis revealed that anthocyanins were the main pigment in blue petals, and that carotenoids controled pigment formation in the orange sepals. Using a system analysis-based approach, 73 and 29 candidate genes related to anthocyanin and carotenoid biosyntheses were identified, respectively. Among these, chalcone synthase 2, chalcone isomerase 1, flavanone 3-hydroxylase 1, flavonoid 3',5'-hydroxylase 1, dihydroflavonol 4-reductase 1, anthocyanidin synthase 1, and anthocyanidin 3-O-glucosyltransferase 1 were considered to be important in regulating the formation of blue petals, and phytoene synthase 1, phytoene desaturaser 1, ζ-carotene desaturase 1, lycopene β-cyclase 3, and β-carotene hydroxylase 2 might play important roles in orange sepal formation. This study improves our understanding of flower color and provides evidence for future molecular breeding of ornamental plants based on flower color modifications.

In view of the ecological, social, and economic importance of Myracrodruon urundeuva Allemão, the objective of this study was to investigate the strategies of this species under drought during its initial phase of development. Two-month-old plants were cultivated under continuous irrigation or no irrigation for 20 d. After this period, the water-stressed plants were rehydrated for 20 d. Physiological, biochemical, and anatomical variables were evaluated on 20^th and 40^th day. Water deficit (25 and 85 % leaf relative content) caused senescence followed by leaf abscission. Growth in height was negatively affected by water deficit (37 % reduction). A decrease in the thickness of the mesophyll was accompanied by a decrease of the total chlorophyll content. Water deficit affected saccharide metabolism and altered cellular component dynamics. Enzyme activities were higher during the rehydration period than during the water stress. There was no increase in lipid peroxidation in plants subjected to water deficit. A reduction in the stomatal opening during water stress was a strategy of reducing water loss through transpiration.

Cytosine methylation plays an important role in plant development by regulating gene expressions. However, few studies have investigated methylation changes during the tissue differentiation and development of perennial plants. Here, the fluorescence-labeled methylation-sensitive amplified polymorphism method was used with eight primer combinations to detect methylation in leaves and xylem obtained at the stages of inflorescence emergence (IE), ovary start growth, and fruit maturity (FM) in two pecan (Carya illinoinensis) cvs. Pawnee and Stuart. The results show that the total methylation in the xylem was generally higher than in the leaves at each stage. Substantial methylation variations were observed at the amplified sites in pecan tissues at the various stages. The methylation patterns changed between the leaf and xylem, with frequencies from 44.97 to 67.01 % over the three stages in the two cultivars, among which the variation frequency between the tissues at the FM stage was the highest for each cultivar. The frequencies of methylation variation between the leaf samples at any two stages ranged from 31.86 to 45.88 %, with higher variation frequencies between the xylem samples (40.90 - 59.44 %) for each cultivar, which is consistent with the comparative results of polymorphism rates between the leaf and xylem over the three stages. Cluster analysis and principal coordinate analysis suggest that the xylem at the IE and FM stages had relatively distant epigenetic relationships with other tissue samples as a whole. This study reveals the patterns of methylation variation and methylation relationships among pecan tissues undergoing different developmental processes, implying the important roles of methylation in tissue differentiation and development of trees. These results lay a theoretical foundation for elucidating the regulatory mechanisms of methylation involved in tree development.

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.