Changes in chloroplast ultrastructure and total content of endogenous cytokinins (CK) were studied during different phases of plant development in transgenic Pssu-ipt tobacco (Nicotiana tabacum L. cv. Petit Havana SR1). Permanent overproduction of CK was found in both rooted (SE) and grafted (G) Pssu-ipt plants in all phases of plant development with the peak in vegetative and flowering phase in the latter ones. No such a correlation was observed in SE on the contrary to control non-transgenic plants (SR1) and grafts (SRG), which showed also CK increase at juvenile and flowering phases. No significant differences in parameters of chloroplast ultrastructure, such as length of chloroplast, starch content, granum width, and number of thylakoids per granum, were proved between chloroplasts from young mature leaves of control and transgenic tobacco during plant ontogeny. Nevertheless, several anomalies in the ultrastructure of cell organelles were found in Pssu-ipt tobacco. Amoeboid shape of chloroplasts was often observed in connection with "tubular clusters" resembling peripheral reticulum. The distinct crystalline structures located in chloroplasts might be formed by LHC protein aggregates. Smaller crystals of unknown composition were found also in mitochondria. Numerous crystalline cores were present in peroxisomes. The alterations might be the result of imbalance of phytohormone content, degradation effect of CK overproduction, or the example of acclimation to permanent stress. and H. Synková, R. Pechová, R. Valcke.
a1_To determine how the use of a given rootstock can influence the functioning of the photosynthetic apparatus of the scion under salt stress, the growth, gas exchange, photosystem II (PSII) efficiency, xanthophyll cycle, and chloroplast ultrastructure of nongrafted,
self-grafted, and pumpkin-grafted (hereafter referred to as rootstock-grafted) cucumber (Cucumis sativus L.) plants were investigated at day 15 after being treated with 90 mM NaCl. The reductions in plant growth of the rootstock-grafted plants were lower than those of the nongrafted and self-grafted plants under 90 mM NaCl. The net photosynthetic rate, stomatal conductance, maximal and effective quantum yield of PSII photochemistry, photochemical quenching coefficient, and effective quantum-use efficiency of PSII in the light-adapted state of the nongrafted and self-grafted plants were significantly decreased under 90 mM NaCl. However, these reductions were alleviated when the cucumber plants were grafted onto the pumpkin (Cucurbita moschata Duch.) rootstock. The intercellular CO2 concentrations were significantly increased in the nongrafted and self-grafted plants under 90 mM NaCl, whereas it was decreased in the rootstock-grafted plants. Nonphotochemical quenching (NPQ) and the deepoxidation state of the xanthophyll cycle were significantly increased under 90 mM NaCl, particularly in the rootstockgrafted plants, suggesting the rootstock-grafted plants had higher potential to dissipate excess excitation energy and reduce the probability of photodamage to PSII. Under 90 mM NaCl, the number of grana was reduced, the thylakoids were swollen, and starch granules accumulated in all plants. However, the damage of chloroplast ultrastructure was alleviated in the rootstock-grafted plants., a2_Taken together, the use of C. moschata rootstock alleviated salt stress in cucumber plants by delaying photoinhibition, probably due to a lower incidence of both stomatal and nonstomatal factors limiting photosynthesis., Z. X. Liu ... [et al.]., and Obsahuje bibliografii
The aim of the current work was to determine whether grafting could improve salinity tolerance of melon and cucumber, and whether possible induction of tolerance to salt stress was associated with the protection of the photosynthetic apparatus. Two greenhouse experiments were carried out to determine gas exchange, mineral composition, growth and yield of melon (Cucumis melo L. cv. Cyrano) and cucumber (Cucumis sativus L. cv. Akito) plants, either ungrafted or grafted onto the Cucurbita hybrid rootstocks (Cucurbita maxima Duch. × Cucurbita moschata Duch.), ‘P360’, and ‘PS1313’, respectively. Plants were grown hydroponically and supplied with two nutrient solutions - a nonsalinized control and a salinized solution which contained 40 mmol L-1 of NaCl. Salinity induced a smaller decrease in leaf area index (LAI), in grafted-compared to ungrafted plants. Similarly, the
PN and gs reduction in NaCl treatment compared to control were significantly lower in grafted plants (34% and 34%, respectively, for melon and 14% and 15.5%, respectively, for cucumber) compared to ungrafted plants (42% and 40%, respectively, for melon and 30% and 21%, respectively, for cucumber). In all grafting combinations, negative correlations were recorded between Na+ and Cl- in the leaf tissue and PN. Grafting reduced concentrations of sodium, but not chloride, in leaves. Under saline conditions a smaller reduction in melon and cucumber shoot biomass dry mass and fruit yield were recorded, with positive correlations between shoot biomass, yield and PN. These results suggest that the use of salt tolerant Cucurbita rootstock can improve melon and cucumber photosynthetic capacity under salt stress and consequently crop performance., Y. Rouphael ... [et al.]., and Obsahuje bibliografii
Among the most important quality parameters of irrigation water used for greenhouse crops, alkalinity of water is considered critical due to its impact on soil or growing medium solution pH. In this study, plant growth, Fe content, photosynthetic pigment content, maximal quantum yield of PSII photochemistry (Fv/Fm), performance index (PI), leaf relative water content (LRWC), and soluble sugars concentration were investigated in nongrafted and grafted tomato (Lycopersicon esculentum Mill. cv. Red stone) plants onto five rootstocks of eggplant (Solanum melongena cv. Long purple), datura (Datura patula), orange nightshade (Solanum luteum Mill.), local Iranian tobacco (Nicotiana tabacum), and field tomato (Lycopersicon esculentum Mill. cv. Cal.jn3), exposed to 0, 5, and 10 mM NaHCO3 concentrations, to determine whether grafting could improve alkalinity tolerance of tomato. Significant depression of leaf area, leaf and stem dry mass, shoot and root Fe content and LRWC under high NaHCO3 level was observed in both grafted and ungrafted plants. The highest reduction in the shoot Fe content was observed at 10 mM sodium bicarbonate in control plants (greenhouse tomato). Moreover, at high HCO3- level, the highest percentage of LRWC reduction was also recorded in ungrafted plants. Values of Fv/Fm and PI decreased significantly at 5 and 10 mM NaHCO3 irrespective of rootstock type. The present study revealed that soluble sugars content, photosynthetic pigments content, Fv/Fm and PI values in plants grafted onto datura rootstock were higher than those in nongrafted and rest of the grafted plants. Thus, the use of datura rootstock could provide a useful tool to improve alkalinity tolerance of tomato plants under NaHCO3 stress., Y. Mohsenian ... [et al.]., and Obsahuje bibliografii