6-苄氨基嘌呤减缓鲜切西兰花的衰老机理分析

为研究6-苄氨基嘌呤（6-benzylaminopurine，6-BA）调控采后西兰花衰老的可能机理，以鲜切西兰花为材料，考察了30 mg/L 6-BA处理对鲜切西兰花内源6-BA含量、总叶绿素含量、菌落总数、乙烯释放量、衰老相关基因表达、乙烯合成相关酶活性及其基因表达的影响。结果表明：6-BA处理可有效延缓西兰花总叶绿素的降解，抑制其菌落总数上升；随着贮藏时间的延长，与对照西兰花内源6-BA含量不断下降不同，外源6-BA处理则维持了贮藏后期组织内较高的6-BA含量，但经煮熟后，处理和对照组的内源6-BA含量均大幅度下降；6-BA处理下调了叶绿素酶2、半胱氨酸蛋白酶5和富含脯氨酸蛋白基因的表达，延缓了叶绿素a/b结合蛋白1基因表达的下降；6-BA处理降低了乙烯合成酶活性及其基因的表达，显著抑制了西兰花的乙烯释放量。总之，外源6-BA维持了鲜切西兰花贮藏后期组织内较高的内源6-BA水平，从而抑制了乙烯的生成，最终减缓了西兰花的衰老进程。

6-Benzylaminopurine Alleviates the Senescence of Fresh-Cut Broccoli through Inhibiting the Production of Ethylene

To elucidate the possible mechanism by which 6-benzylaminopurine (6-BA) regulates the senescence of broccoli, the effects of 30 mg/L 6-BA on the endogenous 6-BA content, total chlorophyll content, total bacterial account, ethylene production, the expression of senescence-related genes, the activities and gene expression of the ethylene-forming enzymes in broccoli were investigated. The results showed that 6-BA treatment could significantly alleviate the degradation of total chlorophyll and inhibit the increase in total bacterial count in broccoli. The endogenous 6-BA content of control broccoli continuously decreased with the extent of storage time, while exogenous 6-BA treatment maintained higher endogenous 6-BA content at the later stage of storage. The endogenous 6-BA content in both the control and 6-BA treatment groups decreased after cooking. Additionally, 6-BA treatment down-regulated the expressions of chlorophyllase gene (2BoCLH2), cysteine protease gene (5BoCP5), proline rich protein gene (BoLSC810), and retarded the decline in the expression of chlorophyll a/b binding protein 1 (BoCAB1). Moreover, 6-BA treatment significantly suppressed ethylene production in broccoli, which might be associated with decreased activity of ethylene synthase and down-regulated expression of BoACS1 and BoACS2. These results suggested that exogenous 6-BA maintained higher endogenous 6-BA level at the later period of storage, thereby inhibited ethylene production, and finally slowed down the senescence of broccoli.