柑橘膨胀素相似基因的克隆及在采后胁迫条件下的表达

Cloning and Characterization of an Expansin-like Gene in 'Navel' Orange Fruit Response to Postharvest Stresses

从柑橘果皮褐变差减cDNA文库中分离出了一个编码膨胀素相似基因的片段,通过RACE技术分离获得了1 083 bp的全长cDNA(CsEXP,GenBank登录号FJ769424),编码254个氨基酸,开放阅读框为52-816 bp间;该成熟蛋白质的分子量为27.05 kD,等电点为7.93。CsEXP在褐变果皮中的表达明显高于对照。CsEXP在胁迫初期的表达分析显示,高温(40℃)抑制CsEXP的表达,而在伤害、低温(4℃)、无氧和乙烯处理后24 h内,CsEXP的表达都上升,表明这些处理诱导了CsEXP基因表达,可能CsEXP在对胁迫刺激的反应中起作用。由于低氧、伤害等胁迫条件都可能诱导果皮褐变的发生,因此CsEXP可能在对果皮褐变相关的胁迫反应中起作用。

A cDNA subtraction library had been constructed to identify differentially expressed genes in peel pitting of citrus fruit.Based on the sequence of a cDNA fragment homologous to expansin gene family,the full-length cDNA（CsEXP,GenBank accession No.FJ769424）of 1 083 nucleotides was cloned from＇Navel orange＇ by rapid amplification of cDNA ends.It was designated as CsEXP,encoded a protein of 254 amino acids with an open reading frame located in the region between 52 and 816 bp.The calculated molecular weight of the mature protein was 27.05 kD and theoretical isoelectric point was 7.93.Exposure of fruit to stresses,including wounding,0% oxygen,low temperature（4℃）,and treatment with ethylene,increased CsEXP mRNA levels in comparison with the control untreated fruit,whereas high temperature（40℃）decreased its mRNA levels.Results implied that this is an anoxic gene.Since low temperature,low oxygen and wounding were suspected factors inducing peel pitting of citrus fruit,the present results provided a clue that CsEXP could play a role in response to peel pitting related stresses.