6-苄氨基嘌呤减缓鲜切西兰花的衰老机理分析

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

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。

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（2Bo CLH2）,cysteine protease gene（5Bo CP5）,proline rich protein gene（Bo LSC810）,and retarded the decline in the expression of chlorophyll a/b binding protein 1（Bo CAB1）.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 Bo ACS1 and Bo ACS2.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.