A polyspecific antiserum against protein extracted from PSTV-infected tomato leaves was prepared and the IgGs were separated by affinity chromatography on a beaded cellulose adsorbent with an immobilized "healthy" antigen. The antibody not adsorbed entered into a preferential reaction with the antigen from PSTV-infected leaves as estimated by an enzyme-linked immunosorbent assay. The immunochemical reactions did not significantly exceed the control background, if antigens from tomato leaves infected with potato viruses X, Y and M were analyzed. By immunoblot technique we revealed, however, that several antigens not detected in healthy leaves appeared in the leaves infected either with PSTV or with viruses X and M. An accumulation of a major antigen having a molecular mass of about 70 kDa was observed in viroid-infected leaves only, suggesting the specificity for viroid infection. The antigen was found not to be an alkaline endoproteinase - the pathogenesis-related protein P-69.
Some antigens with molecular masses approximately 38.0, 23.7 and 22 kDa, which occurred in PSTV-infected leaves and in healthy calluses, were not detectable in PSTV-infected calluses.
No reaction exceeding the control level was observed using enzyme-linked immunosorbent assay for antigens from silver nitrate-treated tomato leaves, although such leaves showed symptoms similar to that caused by viroids.

Exogenous supply of Spd and Spin stimulated ethylone production in detached tobacco leaves kept in the light. Stimulation, that was first detected after 9 but not 6 h of treatment, linearly increased with concentration and was maintained for several h after returning treated leaves to deionized water. Stimulation of ethylene production was prevented by AVG and Co²⁺ and was accompanied by increased activity of ACC synthase and ethylene-forming enzyme. Put, and other diamines, did not give any stimulatory effect. Stimulation was not accompanied by apparent damage of plasmalomina nor was it reversed by Ca⁺ or Put, suggesting that the cationic properties of polyamines are probably not involved. Stimulation might be due to endogenous polyamine accumulation high enough to inhibit the activity of S-adenosylmethionine decarboxylase, so that all S-adenosyhnethionine might be committed to the ethylene pathway. The stimulatory effect of poly a nines acquires particular interest considering that they have so fur been doscribod to inhibit ethylone production in darkened plant tissues. This finding suggests that polyamines may play a regulatory role in plant development by modulating ethylene bio-synthesis under the control of light.

There exist two main mechanisms of allelopathy: 1) direct transfer of metabolites between neighbouring plants during their life and 2) accumulation and transformation of bioactive substances in the environment with their subsequent influence on higher plants. The latter mechanism is similar to that causing soil sickness or soil toxicity. Allelochemicals affect all functions of the living system: photosynthesis, respiration, mineral nutrition, transpiration, immunity, and growth. The initial biochemical effect of allelochemicals seems to be on the synthesis of protein mediated by RNA/DNA. Knowledge of the mechanisms of concrete signals during realization of hereditary codes would serve as a powerful tool for the improvement of crop plant development and productivity.

Divisional activity, intrusive growth of the cell wall and loss of fusiform initials have been studied in Holoptelea integrifolia. The dimensional changes in relation to mean length, length frequency, mean width and length variation in relation to fibre length have also been analysed.

Potato root cultures transformed by_pRiA4 T-DNA do not regenerate plants in vitro spontaneously, but regeneration can be induced by a sequence of callogenesis and regeneration media. Both T_l and T_r-DNA were found by Southern blotting. Regenerated transformants showed characteristic morphological deviations in the in_vitro cultures. Plants in the soil showed differences in the inflorescence and tuber development.

Bromegrass cell suspension cultures, varying in frost hardiness, were immersed ìn distilled water and electrical conductivity of the bathing solutions was measured at various intervals after immersion. It was found that tissue frost-hardened by maintenance at 2‡C leaked more electrolytes than the relatively frost-sensitive tissue grown at 20‡C, but that tissue frost-hardened by abscisic add treatment displayed decreased leakage, despite comparable levels of frost-hardiness having been achieved. It is concluded, in contrast with the conclusion of a previous report, that changes in membrane permeability to electrolytes may not be directly related to the capacity of cells to tolerate freezing stress.

Two ways were tested to obtain the definitive bacterial decontamination of a clone of hybrid walnut culturedin vitro: treatment of the plantlets with Rifampicin and other antibiotic agents, and culture establishmentvia shoot tip expiants. The former failed whereas the latter led to plantlets truly free of contaminants which could be satisfactory propagated, rooted and weaned

Chloroplast DNA from three barley cultivars and from one lettuce cultivar was prepared from chloroplasts isolated by Conventional differential centrifugation. Barley chloroplast DNA size was sensibly lower (130 kpb) than lettuce chloroplast DNA (150 kpb). Chloroplast DNAs from the three barley cultivars showed similar restriction fragment patterns after digestion with: BamHI, EcoRI or HindIII. The lettuce chloroplast DNA restriction pattern was very different from the barley chloroplast DNA restriction pattern.

Seeds ofPetunia nyctaginifloraJuss. a common ornamental garden plant, were treated with two alkylating agents (methyl methane sulphonate and N-methyl-N'-nitro-N-nitrosoguanidine). Six morphological and seven chlorophyll mutants were isolated from M₂ segregating families. The isolated induced mutants are described and genetically analysed.

The interactive effects of certain phytohormones (GA₃, IAA or kinetin) and drought on plant-water relations and mineral accumulation of the three crop plants; maize, cowpea and broad bean, were studied. Phytohormone applications were capable of counteracting to some extent, the adverse effects of drought on transpiration, stomatal frequency, and leaf area.

Allelopathic compounds, including fatty acids, phenolics, flavonoids, terpenoids, and alkaloids, have been found in various plants and soils of different habitats in Taiwan since 1972. For example, in a monoculture of rice plants, phytotoxins were produced during the decomposition of rice residues in soil, suppressed the growth of rice seedlings, and reduced the numbers of tillers and panicles, leading to yield reduction. The allelopathic metabolites are also affected by environmental factors, such as oxygen, temperature, soil moisture, microbial activity, and levels of fertilizers in soil, and allelopathy was pronounced in areas where environmental stresses were severe. Substantial amounts of phytotoxic mimosine and phenolics were released into soil by plant parts of Leucaenaleucocephala, and these suppressed the growth of many understory species except that of L.leucocephala itself. A unique pattern of absence of understory plants was ubiquitous beneathPhyllostachys edulis, due primarily to an allelopathic effect. In a forest pasture intercropping, an aggressive kikuyu grass was planted in a deforested land where Chinese fir grew previously, to help in understanding the mechanism of biological interactions between plants. Aqueous soil leachate and extracts of the grass significantly, retarded the growth of local weeds but not that of the Chinese fir. Allelopathy thus plays an appreciable role in natural vegetation and plantations in Taiwan.

A new method of simultaneous measurement of membrane (E_m) and transorgan (E_tr)electric potential in intactChenopodium rubrum plants and changes in E_m and E_tr under various experimental conditions are described. E_m was measured in mesophyll leaf cells, and E_tr in the same plant as a potential difference between a first pair leaf, tip and roots. The two potentials differed distinctly, E_m averaging-156mV and E_tr -5mV. But the,-changes in E_m and E_tr had approximately the same magnitude and time-course after changing light and darkness or KCl concentration in solution flowing around the leaf or during the photoperiodic induetive cycle. In relation to the same electrode connection they had an opposite polarity. The nature of E_tr and its relation to E_m are discussed.
The measurement of E_tr is much more stable and simpler than that of E_m. The similarity of E_m and E_tr time-courses justifies the use of E_tr measurement in electrophysiological studies as a replacement for E_m measurements especially in intact plants.

The uptake of cadmium and its effect on the growth of potato shoot tips grownin vitro were followed in dependence on cadmium concentration in nutrient medium.
Concentration of 10^-6M Cd²⁺did not substantially affect potato plantlet growth dynamics; but the concentration of 10^-3 M Cd²⁺ showed a strong growth inhibitory effect accompanied with increased cadmium accumulation in both root and shoot tissues.

The effect of short chain fatty acids on the cellular permeability of embryonic axis inGcer arietinum seeds was studied. Octanoic (OCT) and nonanoic (NON) adds, which reduce both germination and growth of the embryonic axis and raise the inhibitor effects of the supraoptimal temperatures (30‡C), induce a greater ionic efflux into the medium (conductivity). NON reduces glucose (3-0-MG) and K⁺ (⁸⁶Rb) uptake during the germinative process, this action being counteracted by fusicoccin (FC) at optimal (25‡C) and supraoptimal temperatures (30 ‡C). Tonoplast and plasmalemma increase their permeability to the K⁺ efflux when NON is present. Addition of NON+FC gives rise to higher values in the efflux rate, the vacuolar compartment being the most affected. Temperatures around zero (2 ‡C) notably reduce the isotope efflux from cytosol and vacuole. NON acid does not significantly affect the efflux of³H-ABA, suggesting that it does not cause any important changes in the phytohormone compartmentation.

Pollen embryos of Brassica juncea (L.) Czern., obtained through anther culture, were examined histologically and histochemically to find explanation for their inability to germinate normally like a zygotic embryo. Most of the embryos lacked a distinct plumule or both plumule and radicle. Anotherabnormal feature of these embryos was the degeneration of cells in the hypocotyl and radicle, whichoccurred either through lysis or cell shrinkage. Reserve food material was mainly in the form of proteinbodies and starch grains. Unlike the zygotic embryos, the pollen embryos lacked lipids. It is concluded thatthe inability of the pollen embryos to germinate normally is due to their structural abnormalities andphysiological immaturity.

A method of cultivation and effectiveness of different light sources and light regimes in photoperiodic induction of flowering in non-rosette long-day plantChenopodium murale L. ecotype 197 are described. Under the described conditions of cultivation 5 days, of continuous light produced by incandescent bulbs (TESLA 74 3x40 W, red 4.9 μWcm-²nn-¹, far-red 7.4 μWcn-2nm-¹, blue 0.25 μW cm-²nn-¹) induced flowering in the majority of plants.

From nine different plant species grown at 1500 cm³ m^-3 CO₂ five responded with a significant increase in stomatal numbers per mm² as compared with plants grown under normal air conditions. Within a collection of twelve french bean cultivars remarkable cultivar differences with regard to the CO₂ enhancement effect on stomatal numbers was found.

In triticale and its parental species, the application of a root osmotic stress induced either a transient increase or an immediate decrease in transpiration rate. The response of wheat (Trticum dicoccum farrum) proved to depend on relative humidity of air. In rye (Secale cerealecv. Petkus) and triticale (T. 300) the effect of NaCl stress was less expressive, than the effect of PEG.

The hypothesis that allelochemicals released from members of the Florida scrub community deter the invasion of fire-prone sandhill grasses was investigated. Constituents of the endemic scrub members, Ceratiola ericoides, Conradina canescens and Calamintha ashei, were examined for their phytotoxic activity. Effects of the plant natural products on the germination and radicle growth of lettuce (Lactuca sativa), as well as little bluestem (Schizachyrium scoparium) and green sprangletop (Leptochloa dubia), two native grasses of the Florida sandhill community, were tested.
The data suggest that ursolic acid and other natural detergents which are released from a source plant enhance the solubilization of allelopathic lipids via micellization. In general, natural surfactants seem to play a significant role in the water transport of lipophilic phytotoxins to target seeds or seedlings.

Germinated seeds ofVicia faba were continuously irradiated at low dose rate of gamma rays (0.05 Gy h-¹) up to a total accumulated dose of 2 Gy. The FPG (fluorescence plus Giemsa) technique of differential chromatid staining was used to monitor the frequency of sister chromatid exchanges (SCEs) in irradiated root tip meristem cells. The results of the experiments have demonstrated that SCE frequency is raised by continuous gamma irradiation only in plant cells containing BrdU in the chromosomal DNA. No effect concerning SCE formation was recorded at continuous irradiation of meristematic cells of Vicia faba with native, i. e. BrdU-nonsubstituted, DNA. In contrast to SCEs, a significant increase was found in the yield of chromosomal aberrations in all variants of irradiation.

Electrophysiological processes were investigated in the reception organ of photoperiodism, cotyledons and first leaves, in a model short-day plantChenopodium rubrum L. (selection 374) within the dark inductive cycle for flowering. Membrane potential (E_m) was measured in cotyledon and first leaf mesophyll of intact plants. The E_m time-course was fairly similar during inductive dark or postinductive light period or in non-inductive continuous light and had a character of irregular oscillations. The most distinct oscillations were found during the postinductive light period. Changes in light régime at the beginning (light off) and the end of inductive dark period (light on) triggered marked transient E_m changes having a character of damped oscillations. Cortical root cells in intact plants did not react to switching light and darkness. Changes in E_m in reception organs during the inductive cycle could not be correlated with the formation and transport of floral stimulus or with reaching the induced state. Thus, the electrophysiological nature of floral stimulus has not been confirmed.

Different NaCl concentrations in a nutrient medium ofGossypium hirsutum L. induced a different decrease in the rates of photosynthesis and photorespiration in two cultivars.

Cultures of isolated mesophyll protoplasts ofBrassica napus L.have shown a positive reaction with the acidic phloroglucinol test for lignin (Wiesner reagent) 30 h after the beginning of the culture period. The reaction was observed in protoplasts and in a very early stage connected with divisions, in which acidic phloroglucinol positive material was primarily deposited like a girdle surrounding the division plane. Brown exudates, which are a serious problem even in young cultures derived from isolated protoplasts, have been secreted into the medium by cells, and also showed a positive reaction. The same staining pattern has been found with toluidine blue 0.