外源Ca~(2+)对高温强光胁迫下小麦叶绿体D_1蛋白磷酸化及光系统Ⅱ功能的影响

用10mmol·L-1CaCl2溶液预处理灌浆期小麦叶片,以水预处理为对照,然后将预处理植株进行高温强光(35℃,1600μmol·m-2·s-1)胁迫,测定胁迫处理过程中小麦旗叶光合电子传递速率、净光合速率、叶绿素荧光参数及D1蛋白的变化,以研究外源Ca2+对高温强光胁迫下小麦叶片类囊体膜D1蛋白磷酸化和PSⅡ功能的影响.结果表明:CaCl2溶液预处理使小麦叶片在高温强光逆境下PSⅡ反应中心发生可逆失活,有效抑制了高温强光下D1蛋白的净降解,保持了较高的D1蛋白磷酸化水平,暗恢复后PSⅡ反应中心活性迅速恢复,全链电子传递速率和PSⅡ电子传递速率恢复至对照水平,维持了较高的PSⅡ原初光化学效率(Fv/Fm)、实际光化学效率(ФPSⅡ)、光化学猝灭系数(qP)和净光合速率(Pn).表明外源Ca2+通过调节小麦叶绿体D1蛋白的周转,促进了PSⅡ的正常运转,减轻了高温强光胁迫对叶片光合机构的损伤.

Effects of exogenous Ca~(2+)on D_1 protein phosphorylation and PSⅡ performances of wheat leaf chloroplasts under high temperature and illumination stress

Aimed to understand the effects of exogenous Ca~(2+) on the D1 protein phosphorylation and PSⅡ performances of wheat leaf chloroplasts under high temperature and illumination stress,wheat leaves at grain-filling stage were sprayed with 10 mmol·L~(-1) of CaCl_2 or water(as control),and then subjected to high temperature and illumination stress(35 ℃ and 1600 μmol·m~(-2)·s~(-1))for various hours,with the changes in photosynthetic electron transport rate(ETR),net photosynthetic rate,chlorophyll fluorescence parameters,and relative amount of phosphorylated and nonphosphorylated D,protein in thylakoid membranes determined.After spraying with Ca~(2+),the PSⅡ reaction center under the stress was reversibly inactivated,the net degradation of D1 protein was effectively restrained,the D_1 protein phosphorylation was maintained at a higher level,and the ETR of whole chain and PS Ⅱ,the maximal photochemical efficiency of PS Ⅱ(F_v/F_m),the actual photochemical efficiency of PS Ⅱ(φPSⅡ),the photochemical quenching coefficient(q_P),and net photosynthetic rate(P_n)were all higher,suggesting that exogenous Ca~(2+) could improve the PS Ⅱ performances and mitigate its damage under high temperature and illumination stress via regulating the turnover of D_1 protein in wheat leaf chloroplasts.