龙眼果肉自溶相关基因DlMC4的克隆和表达分析

Cloning and Expression Analysis of a Pulp Breakdown Relative Gene of DlMC4 in Longan Fruit

果肉自溶是影响龙眼采后果实贮运、货架寿命和贮藏品质的重要因素。本研究通过同源序列比对及PCR技术在龙眼果肉中克隆获得与龙眼自溶相关基因cDNA序列,命名为DlMC4。同源比对及系统进化树分析结果表明,DlMC4与荔枝LcMC氨基酸序列的相似性最高。定量结果表明:在采后常温贮藏期间,果肉自溶指数随DlMC4基因表达量的上升逐步升高,且DlMC4基因在自溶指数较高的‘东壁’果肉中表达量高于自溶指数较低的‘石硖’果肉。果肉中Caspase-4酶活性的分析结果表明,2个品种的DlMC4基因表达与其酶活性和果肉自溶指数呈显著正相关。据此推测,采后贮藏后期果肉中DlMC4基因的上调表达可能对其果肉自溶起促进作用。

The longan pulp breakdown is the important factor which affects the storage, tansportation, shelf life and storage quality of postharvest fruit. In the present study, a gene which is related to pulp breakdown, was recently cloned from longan pulp and named DlMC4 by the homologous sequence alignment. Results of homologous alignment and phylogenetic reconstruction indicated that DlMC4 showed the highest identity to LcMC （Litchi chinensis Sonn.）. PCR analysis revealed that the pulp breakdown index of pulp increased along with the increasing expression of DlMC4 gene during the postharvest room temperature storage. Moreover, the expression of DlMC4 gene was higher in pulp of ＇Dongbi＇ （higher pulp breakdown index） was parallelly higher than that in pulp of ＇Shixia＇ （lower pulp breakdown index）. Caspase-4 enzyme determination and analysis indicated that the expression of DlMC4 gene had a significant positive correlation with enzyme activity and pulp breakdown index in both cultivars. These results suggested that the up-regulated expression of DlMC4 gene in pulp at the late stage of postharvest room temperature storage might contribute to the pulp breakdown.