Effects of Iron Deficiency on Photosynthesis and Photosystem Ⅱ Function in Soybean Leaf
Gas exchange and chlorophyll a fluorescence in soybean plants were investigated to explore the effects of iron deficiency on photosynthesis and photosystern II function in vivo.Iron deficiency induced a drastic decrease in net photosynthesis(Pn).Compared with normal plants,the maximal quantum yield of PSII photochemistry(ψpo)in iron-deficient plants was only slightly lower;whereas,the efficiency with which a trapped exciton can move an electron into the electron transport chain further than QA-(ψo)and quantum yield of electron transport beyond QA(ψEo)were significantly depressed.Iron deficiency also caused a clear enhancement of the relative variable fluorescence at K step(Vk).When exposed to light,iron-deficient plants had considerably lower efficiency of excitation energy capture by open PSII reaction centers(Fv'/Fm'),quantum yield of PSII electron transport(φPSII),and photochemical quenching coefficient(qp),but markedly higher non-photochemical quenching(NPQ).In addition,post-illumination transient increase in chlorophyll fluorescence was clearly enhanced in iron-deficient plants.Basing on these data,we suggest that both the donor and the acceptor sides of PSII complex were damaged by iron deficiency;cyclic electron transport around PSI in iron-deficient soybean plants might play an important role in inducing the excitation energy dissipation and meeting the demand for extra ATP as a compensation for the loss of phosphorylation capability.
iron deficiencyphotosynthesischlorophyll a fluorescencephotosystem II
NETL
NSTL
万方数据
维普
