胡萝卜光合特性昼夜节律及生物钟基因DcRVEa和DcRVEb响应光周期分析

Photosynthetic characteristics of carrot circadian rhythm and photoperiod response of circadian clock genes DcRVEa and DcRVEb

为了解胡萝卜生物钟相关基因REVEILLEs (RVEs)在昼夜节律中的分子调控机制,从胡萝卜基因组中检索获得DcRVEa和DcRVEb基因。对两个光周期不同时间点胡萝卜叶片进行光合参数测定,利用实时荧光定量PCR技术对DcRVEa和DcRVEb基因表达量进行检测与分析。结果显示:DcRVEa和DcRVEb分别含有304和307个氨基酸,均为亲水性蛋白;二级结构以α-螺旋和随机卷曲为主。胡萝卜RVE蛋白序列与其他物种同源性序列相似度为66.69%;DcRVEa与莲(Nelumbo nucifera)进化关系较近, DcRVEb与橡胶树(Hevea brasiliensis)进化关系较近。蛋白互作网络分析结果显示,胡萝卜DcRVEa和DcRVEb与LNK1、LNK2、CCA1、TOC1等生物钟核心元件具有较直接的作用。在两个光周期(48 h)中,胡萝卜叶片净光合速率(P_(n))、气孔导度(G_(s))和蒸腾速率(T_(r))在白天处于较高水平,胞间CO_(2)浓度(Ci)则相反。实时荧光定量PCR结果显示,在两个光周期(48 h)中, DcRVEa和DcRVEb的相对表达量均在黑暗条件下达到峰值。DcRVEa和DcRVEb的表达趋势相似,均响应昼夜节律的变化。本文研究结果为进一步研究胡萝卜生物钟基因DcRVEa和DcRVEb的分子机制提供参考。

In order to understand the molecular regulation mechanism of REVEILLEs(RVEs)in the circadian rhythm of carrot,DcRVEa and DcRVEb genes were obtained from the carrot genome.The photosynthetic parameters of carrot leaves were determined at different time points of two photoperiods.The expression levels of DcRVEa and DcRVEb were detected and analyzed by real-time fluorescence quantitative PCR.The results showed that DcRVEa and DcRVEb contained 304 and 307 amino acids,respectively,and both were hydrophilic proteins.The secondary structures of DcRVEa and DcRVEb were mainlyα-helix and random coil.The homology of carrot DcRVEs protein sequences with other species was 66.69%.DcRVEa was closely related to lotus(Nelumbo nucifera)and DcRVEb was closely related to rubber tree(Hevea brasiliensis).According to the protein interaction network analysis,DcRVEa and DcRVEb interacted directly with circadian clock-related core components,such as LNK1,LNK2,CCA1,and TOC1.During two photoperiods(48 h),net photosynthetic rate(P_(n)),stomatal conductance(G_(s))and transpiration rate(T_(r))were at higher levels at daytime and intercellular CO_(2) concentration(C_(i))showed the opposite trend.Real-time fluorescence quantitative PCR results showed that the relative expression levels of DcRVEa and DcRVEb during two photoperiods(48 h)reached their peak in dark.The expression trends of DcRVEa and DcRVEb were similar and both responded to changes in circadian rhythm.The results of this study provide a reference for further studying on the molecular mechanisms of circadian clock gene DcRVEa and DcRVEb in carrot.