NO对干旱条件下小麦幼苗PSII功能特性的调节效应

以0.1 mmol L^-1 SNP为NO供体，对小麦幼苗根系进行-0.5 MPa PEG胁迫处理，研究了NO对胁迫后叶片电子传递、光能分配和反应中心开放等PSII功能的影响，以探讨NO在干旱条件下对植物光合作用的调节作用。在干旱胁迫的第1天和第3天，SNP处理不但增加了水势(Ψ_w)和叶绿素含量，且能维持PSII反应中心的电子传递(Ф_PSII和F_m/F_o)及潜在高光合效率(F_v/F_o)；干旱胁迫减少了PSII反应中心开放的比例(q_P)和PSII反应中心捕获光能的转化效率，但SNP处理后PSII开放反应中心的比例增加，利于干旱条件下叶片吸收的能量用于光化学反应(Pr)和PSII反应中心安全地耗散过剩光能。综上所述，干旱条件下NO对小麦幼苗叶片的PSII功能具有调节作用。

Modulation of Exogenous Nitric Oxide on Photosystem II Functions in Wheat Seedlings under Drought Stress

Nitric oxide(NO)has emerged as a key molecule involving in tolerating various abiotic stresses that induce physiological responses in plants.To characterize the role of NO in tolerance of photosystem Ⅱ(PSⅡ)to drought stress induced by polyethylene glycol(PEG),we used sodium nitroprusside(SNP)of 0.1 mmol L-1as exogenous NO donor to study the biologically protective effects of NO at a low concentration on PSII functions in wheat(Triticum aestivum L.)seedlings hydroponically grown under-0.5 MPa PEG stress.Under drought stress,SNP supplement increased the water potential(Ψ w )and chlorophyll content, maintained favorable status of electron transport(ФPSⅡ and Fm/Fo)and potential high activity of PSⅡ reaction centers(Fv/Fo)on the first and third days of treatment.The open proportion of PSII reaction centers(qP)and absorbed-light allocation to photochemical reaction(Pr)were higher in the treatment of SNP supplement under drought stress than in only PEG treatment.SNP alleviated drought-induced inhibition to absorbed-energy conversion of open PSII(Fv’/Fm’),safely dissipating excessive light energy in PSⅡ reaction centers.Therefore,NO could modulate the PSⅡ functions in photosynthesis of wheat seedlings hydroponically exposed to PEG stress.