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光系统Ⅱ亚基蛋白R(photosystemⅡsubunit R,Psb R)是光系统Ⅱ的一个小分子亚基蛋白,其在植物光合生理活动过程中发挥重要作用。为探究Psb R基因在白菜型冬油菜(Brassica campestris)抗寒过程中的功能,本研究以强抗寒白菜型冬油菜陇油7号为材料,运用m RNA差异显示技术DDRT-PCR(differential display reverse transcription PCR)和c DNA末端快速扩增技术(rapid-amplification of c DNA ends,RACE)方法从叶片中克隆到Psb R基因(Gen Bank登录号为KC894423)全长。序列分析结果显示,该基因全长为570 bp,编码包含417 bp的一个完整开放阅读框(open reading frame,ORF),其编码138个氨基酸,蛋白分子量约为14.39 k D,等电点为9.42,该蛋白属于Psb R超家族,与甘蓝(B.oleracea var.oleracea)、山嵛菜(Eutrema salsugineum)和芥菜型油菜(B.juncea)的Psb R蛋白相似性关系较近。采用q RT-PCR研究低温胁迫下白菜型冬油菜Psb R基因的相对表达量以及应用CIRAS-2便携式光合作用测定系统和FMS-2便携脉冲调制式荧光仪研究自然降温过程中冬油菜功能叶的净光合速率(Pn)和光合系统Ⅱ(photosystemⅡ,PSⅡ)原初光能转化效率(Fv/Fm)。研究结果表明,随着胁迫温度(4℃,-4℃和-8℃)降低,Psb R相对表达量下降,而Pn和Fv/Fm也随自然温度降低而下降,说明低温可能会抑制Psb R基因的表达,进而导致白菜型冬油菜光合速率下降、光系统Ⅱ光能转化效率降低。研究结果为解析白菜型冬油菜Psb R基因的生物学功能和抗寒机制提供了部分理论依据。
Photosystem Ⅱ subunit R (Psb R) is a small subunit protein of photosystem Ⅱ, which plays an important role in the photosynthetic physiological activities of plants. In order to explore the function of Psb R gene in the cold-tolerance of Brassica campestris, we used DDRT-PCR (Differential Display The full length of Psb R gene (GenBank accession number KC894423) was cloned from leaves by reverse transcription PCR and rapid amplification of cDNA ends (RACE). Sequence analysis showed that the full length cDNA was 570 bp and encoded a 417 bp open reading frame (ORF) encoding 138 amino acids with a molecular weight of 14.39 kD and an isoelectric point of 9.42 , Which belongs to the Psb R superfamily and has a close relationship with the Psb R protein of B. oleracea var. Oleracea, Eutrema salsugineum and B.juncea. QRT-PCR was used to study the relative expression of PsbR gene in Brassica campestris var. Chinensis (Brassica napus L.) under low temperature stress. The function of Psb R gene in winter rape was studied by using CIRAS-2 portable photosynthesis system and FMS-2 portable pulse- Net photosynthetic rate (Pn) and photosystemⅡ (PSⅡ) primary light energy conversion efficiency (Fv / Fm). The results showed that the relative expression of Psb R decreased with the decreasing of stress temperature (4 ℃, -4 ℃ and -8 ℃), while Pn and Fv / Fm also decreased with the decrease of natural temperature, indicating that hypothermia might inhibit Psb R Gene expression, which in turn led to decreased photosynthetic rate in cabbage-type rapeseed, photosystem Ⅱ light energy conversion efficiency decreased. The results provide some theoretical basis for the analysis of the biological function and cold resistance mechanism of Psb R gene in Brassica campestris.