The difference of photochemical activity and energy distribution on cut chrysanthemum varieties with different heat tolerance under high temperature stress
In order to explore the effects of high temperature stress on photosynthesis,PSⅡ and PSI func-tions of cut chrysanthemums leaves,three cut chrysanthemums with different heat resistance,such as'Weinisi'(heat-resistant variety),'Zijingling'(medium heat-resistant variety)and'Kaisahong'(heat-sensitive variety),were treated at 45℃ for 12 h.The effects of high temperature stress on growth,photosynthetic pa-rameters,operation of photosynthetic electron transport chain in photosynthetic apparatus,photosynthetic related genes of cut flower chrysanthemum were studied.The results showed that the'Weinisi'remained upright under high temperature stress,while the'Kaisahong'were severely weakened,the water retention capacity of the blade is poor.Under high temperature stress,Pn of the'Weinisi','Zijingling'and'Kaisahong'decreased by 37.31％,114.92％and 104.34％,respectively,compared with the control,it showed that the photosynthetic capacity decreased under high temperature stress.The differential fluorescence kinetics of OK and OJ phases showed positive L-band and positive K-band in different varieties under high temperature stress,indicating that the activity of oxygen-evolving-complex was inhibited,the connection of PSⅡ unit en-ergy was down,and PSⅡ antenna structure was damaged,which was one of the reasons for the decreased photosynthesis under high temperature stress.Under high temperature stress,'Weinisi'had more photo-chemical energy available than'Zijingling'or'Kaisahong',because more energy was captured by the PSⅡ re-action center and entered the electron transport chain through maintaining a high level of maximum quan-tum yield for primary photochemistry(φPo),Probability that an electron moves further than QA-(ψEo),and a low level of the quantum yield of energy dissipation(φDo).In addition,under high temperature stress,the ef-ficiency with which an electron from the intersystem electron carriers is transferred to reduce end electron acceptors at the PSI acceptor side(6Ro)was decreased and the activity of PSI in'Weinisi',indicating that more PSI participated in cyclic electron transport.Meanwhile,the expression levels of CmrbcL,CmpsbA,CmpsaA and CmpsaB genes could be maintained to reduce photoinhibition,enhance photosynthesis,and thus'Weinisi'had better heat resistance.This study systematically elucidated the differences of photo-chemical activity and energy distribution of different heat resistant cut chrysanthemums under high tem-perature stress,indicating that different heat resistant cut chrysanthemums varieties have different heat stress protection mechanisms,which provides a theoretical basis for the breeding.
cut chrysanthemumhigh temperature stressphotochemical activityenergy distribution
万方数据
维普
