Two Rubisco activase isoforms may play different roles in photosynthetic heat acclimation in the rice plant.
Two Rubisco activase isoforms may play different roles in photosynthetic heat acclimation in the rice plant.
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DOI：
10.1111/j.1399-3054.2009.01344.x
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发表时间：
2010-05
影响因子：
6.4
通讯作者：
Dun Wang;Xiao-Fei Li;Zheng Zhou;Xu-Ping Feng;Wan-Jun Yang;D. Jiang
中科院分区：
文献类型：
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作者：
Dun Wang;Xiao-Fei Li;Zheng Zhou;Xu-Ping Feng;Wan-Jun Yang;D. Jiang
对一些植物的研究表明，逐渐提高生长温度或高温预处理可导致明显的光合适应高温。为了测试这种适应是否由Rubisco活化酶（RCA）介导的核酮糖1，5-二磷酸羧化酶/加氧酶（Rubisco，EC 4.1.1.39）活化的热适应引起，使用4天热应激处理[40/30 ℃（白天/夜晚）]，随后在对照条件[30/22 ℃（白天/夜晚）]下恢复3天，测定水稻中RCA大同种型（RCA（L））和RCA小同种型（RCA（S））的基因表达。从mRNA水平和蛋白质水平来看，热胁迫显著诱导了RCA（L）的表达。相关分析表明，无论在高温胁迫下还是在正常条件下，RCA（S）蛋白含量与Rubisco初始活性和净光合速率（Pn）均呈极显著相关。Rubisco-RCA复合物的免疫印迹分析表明，热驯化水稻叶片中RCA（L）与Rubisco的比值显著增加。此外，表达增强量的RCA（L）的转基因水稻植物在Pn和Rubisco初始活性方面表现出更高的耐热性，并且在高温下比野生型（WT）植物和表达增强量的RCA（S）的转基因水稻植物生长更好。在正常条件下，表达增强量的RCA（S）的转基因水稻植株比表达增强量的RCA（L）的转基因水稻植株和野生型植株表现出更高的Pn和产生更多的生物量。这些结果表明，热诱导的RCA（L）可能在光合适应中起重要作用，而RCA（S）在维持正常条件下Rubisco初始活性中起重要作用。
Studies on some plant species have shown that increasing the growth temperature gradually or pretreating with high temperature can lead to obvious photosynthetic acclimation to high temperature. To test whether this acclimation arises from heat adaptation of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) activation mediated by Rubisco activase (RCA), gene expression of RCA large isoform (RCA(L)) and RCA small isoform (RCA(S)) in rice was determined using a 4-day heat stress treatment [40/30 degrees C (day/night)] followed by a 3-day recovery under control conditions [30/22 degrees C (day/night)]. The heat stress significantly induced the expression of RCA(L) as determined by both mRNA and protein levels. Correlative analysis indicated that RCA(S) protein content was extremely significantly related to Rubisco initial activity and net photosynthetic rate (Pn) under both heat stress and normal conditions. Immunoblot analysis of the Rubisco-RCA complex revealed that the ratio of RCA(L) to Rubisco increased markedly in heat-acclimated rice leaves. Furthermore, transgenic rice plants expressing enhanced amounts of RCA(L) exhibited higher thermotolerance in Pn and Rubisco initial activity and grew better at high temperature than wild-type (WT) plants and transgenic rice plants expressing enhanced amounts of RCA(S). Under normal conditions, the transgenic rice plants expressing enhanced amounts of RCA(S) showed higher Pn and produced more biomass than transgenic rice plants expressing enhanced amounts of RCA(L) and wild-type plants. Together, these suggest that the heat-induced RCA(L) may play an important role in photosynthetic acclimation to moderate heat stress in vivo, while RCA(S) plays a major role in maintaining Rubisco initial activity under normal conditions.