The efficiency of photosynthetic electron transport depends on the coordinated interaction photosystem II (PSII) and I (PSI) in electron-transport chain. Each contains distinct pigment-protein complexes that harvest light from different regions visible spectrum. energy is utilized an endergonic reaction at each photosystem. Recent evidence has shown a large variability PSII/PSI stoichiometry plants grown under environmental irradiance conditions. Results this work are consistent with notion...

In 27 C4 grasses grown under adequate or deficient nitrogen (N) supplies, N-use efficiency at the photosynthetic (assimilation rate per unit leaf N) and whole-plant (dry mass total level was greater in NADP-malic enzyme (ME) than NAD-ME species. This due to lower N content NADP-ME leaves because neither assimilation rates nor plant dry differed significantly between two subtypes. Relative NAD-ME, had vivo Rubisco catalytic sites) vitro turnover (k(cat); 3.8 versus 5.7 s(-1) 25 degrees C)....

Abstract Cyclic electron flow (CEF) around photosystem I has a role in avoiding photoinhibition of II (PSII), which occurs under conditions the rate photodamage to PSII exceeds its repair. However, molecular mechanism underlying how CEF contributes photoprotection is not yet well understood. We examined effect impairment and thermal energy dissipation (qE) on using (pgr5) qE (npq1 npq4) mutants Arabidopsis (Arabidopsis thaliana) exposed strong light. Impairment by mutation pgr5 suppressed...

Photosystem II plays a central role not only in energy transduction, but also monitoring the molecular redox mechanisms involved signal transduction for acclimation to environmental stresses. Central regulation of photosystem (PSII) function as light‐driven machine higher plant leaves, is an inevitable photo‐inactivation one PSII after 10 6 –10 7 photons have been delivered leaf, although act photoinactivation per se requires photon. acclimated pea leaves shows reciprocity between irradiance...

Abstract. Pea plants ( Pisum sativum L., cv. Greenfeast) were grown for 17d (150 μmol photons m −2 s −1 ; 12h light/12 h dark) and then exposed to moderate levels of supplementary ultraviolet‐B radiation (UV‐B: 280–320 nm) during the light cycle. The total soluble leaf protein, maximum Rubisco activity, polypeptide mRNA transcript subunits determined in mature third pair from base plants. Total protein per unit area showed little change after 1 d but declined by 33% 3d UV‐B exposure....

ABSTRACT Molecular analyses of plants have revealed a number genes whose expression changes in response to high light (HL), including the H 2 O scavenger, ASCORBATE PEROXIDASE ( APX2 ). We carried out screen Arabidopsis thaliana for lesions that alter HL‐induced identify components abiotic stress signalling pathways. High was used as it can be instantaneously applied or removed and accurately measured. identified alx mutations causing altered expression. Here we describe gain‐of‐function...

Leaf anatomy of C3 plants is mainly regulated by a systemic irradiance signal. Since the anatomical features C4 are different from that plants, we investigated whether signal regulates leaf structure and photosynthetic performance in sorghum (Sorghum bicolor), plant. Compared with growth under ambient conditions (A), no significant changes were observed newly developed leaves shading young alone (YS). Shading mature (MS) or whole (S), on other hand, caused shade-leaf leaves. By contrast,...

• We studied how different color lights cause gradients of photoinhibition within a leaf, to attempt resolve the controversy whether photon absorption by chlorophyll or manganese (Mn) is primary photoinhibition, as suggested excess-energy hypothesis two-step hypothesis, respectively. Lincomycin-treated leaf discs were photoinhibited white, blue, green red light. Combining microfiber fluorometer, fiber-thinning technique and micro-manipulator enabled us measure fluorescence signals leaf....

Abstract Light damages photosynthetic machinery, primarily photosystem II (PSII) and it results in photoinhibition. A new photodamage model, the two-step suggests that to PSII initially occurs at oxygen evolving complex (OEC) by light energy absorbed manganese reaction center is subsequently damaged pigments due limitation of electrons center. However, still uncertain whether this model applicable under visible as absorbs only weakly. In present study, we identified initial site upon...

Abstract Salinity is an important abiotic stressor that negatively affects plant growth. In this study, we investigated the physiological and molecular mechanisms underlying moderate high salt tolerance in diploid (2×) tetraploid (4×) Robinia pseudoacacia L. Our results showed greater H 2 O accumulation higher levels of antioxidative enzymes non-enzymatic antioxidants 4× plants compared with 2× under stress. addition, leaves maintained a relatively intact structure to corresponding...

The role of high-light-induced chloroplast movement in the photoprotection facultative shade plant Tradescantia albiflora was investigated by comparison with pea (Pisum sativum L.) leaves, both grown 50 [mu]mol photons m-2 s-1. Photoinactivation photosystem II (PSII) vivo induced 1.1% CO2 varying either duration (0-2 h) illumination (fixed at 1800 s-1) or irradiance (0-3000 a fixed (1 after infiltration leaves water lincomycin (an inhibitor chloroplast-encoded protein synthesis). At all...

We found similarities between the effects of low night temperatures (5 degrees C-10 C) and slowly imposed water stress on photosynthesis in grapevine (Vitis vinifera L.) leaves. Exposure plants growing outdoors to successive chilling nights caused light- CO(2)-saturated photosynthetic O(2) evolution decline zero within 5 d. Plants recovered after four warm nights. These responses were confirmed potted plants, even when roots heated. The inhibitory greater a period illumination, probably...