Limited mesophyll diffusion conductance to CO(2) (g(m)) can significantly constrain plant photosynthesis, but the extent of g(m)-limitation is still imperfectly known. As g(m) scales positively with foliage photosynthetic capacity (A), the CO(2) drawdown from substomatal cavities (C(i)) to chloroplasts (C(C), C(i)-C(C)=A/g(m)) rather than g(m) alone characterizes the mesophyll diffusion limitat...

in order to investigate the responses of sardari wheat ecotypes to drought stress, 12 spikes of sardari wheat were selected from different regions of kurdistan province and planted as head to row. in the second year, a split- plot factorial field experiment was conducted. in this experiment water stress and irrigation were considered as the levels of main factor and 12 sardari wheat ecotypes al...

Infectious material was formed at an early stage, and migrated into the mesophyll from the epidermis of tobacco leaves (Nicotiana tabacum cv. Samsun NN) during the period of 1 to 3 hours after inoculation with tobacco mosaic virus (TMV). The activity of membrane-bound Mg(2+)-activated ATPase from the mesophyll was stimulated two to four times within 30 minutes after inoculation with 1.0 microgr...

The blue emission anisotropy, r, of two lipophilic probes, diphenylhexatriene (DPH) and its trimethyl-ammonium derivative (TMA-DPH), has been measured in foliar Lupinus albus L. protoplasts for the first time by flow cytometry. Distinctive values have been obtained for protoplasts of epidermal and mesophyll origin, identified by their intensities of chlorophyll fluorescence. Fluorescence micros...

The genes rbcS and rbcL encode, respectively, the small and large subunits of the photosynthetic carbon dioxide fixation enzyme ribulose bisphosphate carboxylase/oxygenase. There is a single rbcL gene in each chloroplast chromosome; a family of rbcS genes is located in the nuclear genome. These two genes are not expressed in mesophyll cells but are in adjacent bundle-sheath cells of leaves of t...

The pyruvate,orthophosphate dikinase (PPDK) gene coding the chloroplast enzyme involved in C4 photosynthesis has a dual promoter system. The first promoter is responsible for the transcription of a larger transcript and its product is targeted to the chloroplast (hence, it is designated as C4Pdk promoter) while the second promoter is responsible for the transcription of a smaller transcript and...

AUXIN RESPONSE FACTOR7 (ARF7) is one of five ARF transcriptional activators in Arabidopsis thaliana that is proposed to regulate auxin-responsive expression of genes containing TGTCTC auxin response elements in their promoters. An Arabidopsis mutant (nonphototropic hypocotyl4-1[nph4-1]) that is a null for ARF7 showed strongly reduced expression of integrated auxin-responsive reporter genes and ...

Addition of millimolar sodium glyoxylate to spinach (Spinacia oleracea) chloroplasts was inhibitory to photosynthetic incorporation of (14)CO(2) under conditions of both low (0.2 millimolar or air levels) and high (9 millimolar) CO(2) concentrations. Incorporation of (14)C into most metabolites decreased. Labeling of 6-P-gluconate and fructose-1,6-bis-P increased. This suggested that glyoxylate...

Plants usually experience dynamic fluctuations of light intensities under natural conditions. However, the responses of mesophyll conductance, CO2 assimilation, and photorespiration to light fluctuation are not well understood. To address this question, we measured photosynthetic parameters of gas exchange and chlorophyll fluorescence in tobacco leaves at 2-min intervals while irradiance levels...

The development of a plant leaf is a meticulously orchestrated sequence of events producing a complex organ comprising diverse cell types. The reticulate class of leaf variegation mutants displays contrasting pigmentation between veins and interveinal regions due to specific aberrations in the development of mesophyll cells. Thus, the reticulate mutants offer a potent tool to investigate cell-t...