Effect of iron,zinc and manganese shortage-induced change on photosynthetic pigments,some osmoregulators and chlorophyll fluorescence parameters in lettuce

Although the beneficial role of Fe, Zn, and Mn on many physiological and biochemical processes is well established, effects of each of these elements on chlorophyll (Chl) a fluorescence and photosynthetic pigment contents is not well studied. The objective of this study was to evaluate effects of Fe, Zn, and Mn deficiency in two lettuce cultivars. The parameters investigated could serve also as physiological and biochemical markers in order to identify stress-tolerant cultivars. Our results indicated that microelement shortage significantly decreased contents of photosynthetic pigments in both lettuce cultivars. Chl a fluorescence parameters including maximal quantum yield of PSII photochemistry and performance index decreased under micronutrient deficiency, while relative variable fluorescence at J-step and minimal fluorescence yield of the dark-adapted state increased under such conditions in both cultivars. Micronutrient deficiency also reduced all parameters of quantum yield and specific energy fluxes excluding quantum yield of energy dissipation, quantum yield of reduction of end electron acceptors at the PSI, and total performance index for the photochemical activity. Osmoregulators, such as proline, soluble sugar, and total phenols were enhanced in plants grown under micronutrient deficiency. Fe, Zn, and Mn deficiency led to a lesser production of dry mass. The Fe deficiency was more destructive than that of Zn and Mn on the efficiency of PSII in both lettuce cultivars. Our results suggest that the leaf lettuce, which showed a higher efficiency of PSII, electron transport, quantum yield, specific energy fluxes, and osmoregulators under micronutrient deficiency, was more tolerant to stress conditions than crisphead lettuce.     

Investigation of the cell structure and organelles during autolytic PCD of Antirrhinum majus “Legend White” petals

Protoplasma - One of the classes of the plant developmental programmed cell death (PCD) is vacuolar cell death or autolysis. The results of the transmission electron microscope (TEM) studies...     

The effects of colchicine-induced autotetraploidy on selected characteristics of nuruozak (<Emphasis Type="Italic">Salvia leriifolia</Emphasis>)

Nuruozak (Salvia leriifolia Benth), is a perennial herbaceous plant that is endemic to Iran and has recently been introduced as a medicinal plant. Artificial polyploidy is an efficient method to increase the production of secondary metabolites and can result in a whole spectrum of genetic, molecular and physiological modifications. In order to produce an autotetraploid population of nuruozak, various concentrations of colchicine (0.00, 0.05, 0.10, 0.20 or 0.50% w/v) were applied to the seeds and shoot apical meristems of young seedlings at the fourth leaf-stage. Microscopic studies, flow cytometry analysis and chromosome counting were conducted to select tetraploid nuruozak plants. Furthermore, the effects of ploidy level on the essential oil content and composition and biomass production of nuruozak plants, as well as selected structural and physiological characteristics were studied. Based on the number of the obtained tetraploids, treatment of shoot apical meristems was more efficient than seed treatment. Structural and phytochemical characteristics, chlorophyll content and photosynthetic rate were affected by the increase in ploidy level. In addition to the higher potential in biomass production, tetraploid plants produced eight new compounds which were absent in diploids.