两品种猕猴桃果实采后淀粉降解特性比较分析

Comparative Analysis of Starch Degradation Characteristics of Two Varieties of Kiwifruit After Harvest

为探究猕猴桃果实采后淀粉降解规律,本试验以红阳(HY)和翠玉(CY)猕猴桃果实为材料,比较分析了不同品种猕猴桃果实采后淀粉含量变化以及淀粉降解相关基因的表达模式。结果表明,猕猴桃采后25℃贮藏过程中,HY猕猴桃果实硬度迅速下降并伴随出现乙烯跃变,CY果实硬度缓慢下降但并未出现乙烯释放高峰。2个品种猕猴桃果实的淀粉含量随贮藏时间的延长显著下降。扫描电镜(SEM)结果显示,随着贮藏时间的延长,2个品种猕猴桃果实淀粉粒表面的光滑球面均出现不同程度的消化和破碎,说明淀粉存在酶促降解。同时,HY猕猴桃果实贮藏后期的乙烯释放速率极显著高于CY猕猴桃(P<0.001)。HY猕猴桃果实外果肉中淀粉含量在贮藏前期(0~2 d)极显著高于CY猕猴桃(P<0.01),但在贮藏后期(8~12 d)极显著低于CY猕猴桃(P<0.001);HY猕猴桃果实果心中淀粉含量在贮藏前期(2~4 d)与CY猕猴桃无显著差异,但在贮藏后期(6~12 d)极显著低于CY猕猴桃(P<0.001)。本研究结果为进一步揭示猕猴桃果实采后淀粉降解机理提供了一定的理论依据。

In order to explore the degradation of starch in postharvest fruit,the change of starch contents and the expression pattern of genes related to starch degradation in postharvest Hongyang and Cuiyu kiwifruits were compared and analyzed.Results showed that the firmness of Hongyang fruit decreased rapidly with the occurrence of ethylene climax,but the firmness of Cuiyu fruit decreased slowly without ethylene release peak.The starch content decreased with the prolongation of storage time.SEM results showed that with the increase of storage time,the smooth surface of the starch was digested and broken to different degrees,indicating the enzymatic degradation of starch occurred in the two varieties of kiwifruit.Meanwhile,it was found that the ethylene production of Hongyang fruit was significantly higher than that of Cuiyu fruit(P<0.001).During storage,the starch content in the outer pericarp of Hongyang fruit was significantly higher than that of Cuiyu fruit in the early storage period(0-2 d)(P<0.01),but significantly lower than that of Cuiyu fruit in the later storage period(8-12 d)(P<0.001);The starch content in the core of Hongyang fruit was not significantly different from that of Cuiyu fruit in the early storage period(2-4 d),but it was significantly lower than that of Cuiyu fruit in the later storage period(6-12 d).These results provide a theoretical basis for further revealing the mechanism of starch degradation in the postharvest of kiwifruit.