| Eggplant (Solomon melongena L.) is susceptible to harm living through the summer. High temperature stress has a bad influence on the quality and output, so it is a problem badly in need of handling the production and enhance the heat tolerance of eggplant in summer. Calcium is not only a major necessary element of plant but also a second messager involved in responding and adapting to the outside environment. Ca2+ play an important role in message transduction of the environmental stress. The paper studied the mechanism of heat tolerance of different varieties and the influence on the antioxidative system which TFP, W7 and Ca2+ have in eggplant seedlings under high temperature stress. l.The effects of high temperature stress on heat injury index, recovery index, electrolytic leakage, Pro and soluble sugar content in eggplant seedling of 14 varieties were investigated. The result showed that high temperature stress at eggplant seedling stage led to the increase of electrolytic leakage, Pro and soluble sugar content, the aggravation of heat injury index but the decrease of soluble sugar content; It was proposed that heat injury index, recovery index, electrolytic leakage and Pro content might be suitable for selecting heat-tolerant eggplant genotype in breeding phase except soluble sugar content.2 The heat injury index .electrolytic index and Pro content was investigated under the high temperature of 43/38"C(day/night). It indicated that Nl was the most heat-tolerant to the high temperature stress, Kl l(Kuaiyuanqie),R12(Erminqie),C13(Chiqie), G14(Gon-gguohongqie) were the most sensitive to the high temperature stress and C2(Cihongqie), F3(Fengyan No.2), F4(Fulongqie), Y5 (Yuanza No.2), X6(Xianluqie), B7(Beijignliu-yeqie), Y8(Yeqie No.2), N9(Nianmoqie), Bl1(Beijingwuyeqie) were the intermediate.3 After being enhanced or blocked Ca2+-CaM messenger transduction by pretreating the eggplants of Nongyouqie and Erminqie with external Ca2+ and calmodulin antagonists TFP and W7, production rate of O2, MDA content, SOD and POD activity under high temperature stress of 40'C(day/night)were investigated. The results show that external Ca2+treatment enabled the seedlings to keep relatively high activity of SOD and POD in eggplant seedling, at the same time, lower the production rate of O2 and MDA content, onthe contrary, calmodulin antagonist TFP and W7 led to more rapid loss of SOD and POD activity and higher MDA content, production rate of 02'. These results indicated that external Ca2+ can enhance the intrinsic heat tolerant of eggplant seedlings. This enhancement requires the entry of external Ca2+ into cells and the mediation of intracellar calmodulin,and is associated with the increase of antioxidant enzymes activity.4 The GSH and Pro content of Nongyouqie and Erminqie were investigated under 40 "C(day/night) with external Ca2+ and calmodulin antagonist pretreated. The content of Pro appear to be high-low-high and the content of GSH decreased. It showed that exogenous Ca2+pretreatment can alleviate the damage of GSH content and the accumulation of Pro caused by high temperature stress; on the contrary, TFP and W7 pretreatment can reverse the effect of exogenous Ca2+ pretreatment The results suggested that Ca2+-CaM messager system might regulate the heat tolerance of eggplant seedlings by affecting the content of some antioxidant substance.5 Ca2+-CaM messenger transduction can be blocked by pretreating with TFP or W7, but can be stimulated by pretreating with external Ca2+. External Ca2+ can adjust the activity of antioxidant enzymes and the content of antioxidant substance, enhance the antioxidant ability and adapt to the high temperature stress. It can be inferred that Ca2*-CaM messenger transduction can regulate gene expression and strengthen the ability of adapting to the high temperature stress. It also proved that Ca2+-CaM messenger transduction play an important role in the heat tolerance of eggplant seedlings indirectly.
|
PDF Full Text Request