昼间亚高温影响番茄叶片光合及PSⅡ活性的钙素调控作用

Regulation of Calcium on Photosynthesis and PS Ⅱ Activity of Tomato Leaves Under Daytime Sub-High Temperature Stress

为分析番茄叶片光合作用及光系统Ⅱ(PSⅡ)活性对亚高温逆境响应的钙素调控作用。试验以番茄(Ly-copersicon esculentum Mill.)辽园多丽为试材,研究了CaCl2、EGTA(钙螯合剂)、LaCl3(钙通道阻塞剂)预处理对亚高温胁迫下番茄叶片的叶绿素含量、净光合速率及叶绿素荧光参数的影响。结果表明:昼间亚高温显著抑制了番茄叶片的净光合速率(Pn),降低了叶绿素含量、光系统II最大光化学效率(Fv/Fm)、实际光化学量子效率(ΦPSⅡ)、电子传递速率(ETR)和光化学猝灭系数(qP),提高了初始荧光(Fo)和非光化学猝灭系数(NPQ),对气孔导度(Gs)、蒸腾速率(Tr)、气孔限制值(Ls)有一定的影响;增施CaCl2显著提高了亚高温胁迫下番茄叶片的叶绿素含量和Pn,且使Fo、Fv/Fm、ΦPSⅡ、NPQ均提高到对照水平,ETR和qP提高到接近对照水平,表明增施CaCl2可缓解亚高温对番茄叶片PSⅡ活性的影响,但对Ls和胞间CO2浓度(Ci)影响不大;增施钙抑制剂(EGTA、LaCl3)进一步加重了亚高温胁迫对番茄叶片PSⅡ的伤害。昼间亚高温降低番茄叶片光合速率与气孔因素无关,可能主要是通过伤害PSⅡ所导致的PSⅡ活性下降所致;而增施CaCl2可以缓解亚高温对PSⅡ的伤害,维持PSⅡ较高的活性,从而缓解亚高温对番茄净光合速率的影响。

To analyze the regulation of calcium on photosynthesis and PS Ⅱ activity in tomato leaves under sub-high temperature stress.During the period of sub-high temperature,tomatoes liaoyuanduoli grown in the plastic pot were pretreated with CaCl2,EGTA（Ca2＋ chelator）,and LaCl3（Ca2＋ channel inhibitor）.Chlorophyll content,photosynthetic rate and chlorophyll fluorescence parameters were investigated.The results showed that photosynthesis in tomato leaves pretreated with daytime sub-temperature was significantly inhibited tomato,and chlorophyll content,Fv/Fm,ΦPS Ⅱ,ETR and qP decreased,but Fo and NPQ increased.Furthermore there were some influences on Gs,Tr and Ls;Chlorophyll content and net photosynthesis rate（Pn） in tomato leaves pretreated with CaCl2 were significantly increased,and there was no difference in the Fo,Fv/Fm,ΦPS Ⅱ and NPQ between CaCl2 pretreatment and control,while qP,ETR was slightly lower than that of control,these results showed that there was high PS Ⅱ activity in tomato leaves pretreated with CaCl2,however,Ls and Ci were not affected;The PS Ⅱ activity in tomato leaves pretreated with calcium inhibitor suffered more serious injuries.Inhibition of photosynthesis in daytime sub-high temperature stress had no relation with stomatal factors,the reduction of photosynthesis may be deceased PS Ⅱ activity which was caused by the damage of PS Ⅱ.CaCl2 pretreatment effectively alleviated the damage to the function of PS Ⅱ in tomato leaves under sub-high temperature stress,and maintained higher PS Ⅱ activity.Consequently CaCl2 can relieve the inhibition of photosynthesis due to daytime sub-high temperature stress.