Transgenic tobacco plants expressing antisense ferredoxin-NADP(H) reductase transcripts display increased susceptibility to photo-oxidative damage.

摘要: Ferredoxin-NADP(H) reductase (FNR) catalyses the final step of photosynthetic electron transport in chloroplasts. Using an antisense RNA strategy to reduce expression this flavoenzyme transgenic tobacco plants, it has been demonstrated that FNR mediates a rate-limiting photosynthesis under both limiting and saturating light conditions. Here, we show these FNR-deficient plants are abnormally prone photo-oxidative injury. When grown autotrophic conditions for 3 weeks, specimens with 20-40% extant undergo leaf bleaching, lipid peroxidation membrane damage. The magnitude effect was proportional intensity extent depletion, accompanied by morphological changes involving accumulation aberrant plastids defective thylakoid stacking. Damage initially confined chloroplast membranes, whereas Rubisco other stromal proteins began decline only after several weeks growth, paralleled partial recovery NADPH levels. Exposure moderately high irradiation resulted rapid loss capacity singlet oxygen leaves. collected results suggest extensive damage sustained impaired caused building up toxic levels tissues, as direct consequence over-reduction chain