黄秋葵果实发育过程中细胞壁组成成分、糖代谢及相关酶活性的变化

Developmental changes of okra fruits in cell wall composition,saccharometabolism and related enzymatic activities

以黄秋葵(Abelmoschus esculentus L.)卡里巴和油绿一号果实为试验材料,测定果实发育过程中细胞壁组成成分、糖分积累及相关酶活性的变化,并对纤维素含量与纤维素代谢酶活性进行了相关性分析。结果表明:两个品种黄秋葵果实的适宜采收期为花后6~7 d,在果实发育过程中木质素和半纤维素含量均先上升后下降,纤维素含量不断上升,纤维素合酶(CesA)和纤维素酶(Kor)活性不断上升,蔗糖合酶(SS-I)、内切葡聚糖酶(Cx)和外切葡聚糖酶(C1)活性先升高后降低,β-葡萄糖苷酶(β-GC)活性不断降低。卡里巴果实中木质素、半纤维素、纤维素含量和纤维素代谢相关酶活性均高于油绿一号。相关性分析结果表明,CesA和Kor酶活性与纤维素含量呈显著正相关,β-GC酶活性与纤维素含量呈极显著负相关。糖分含量测定结果显示,两个品种果实中的蔗糖含量均呈上升趋势,果糖与葡萄糖的含量均在花后6 d达到峰值,果实中蔗糖磷酸合成酶(SPS)和蔗糖转化酶(SAI、BAI、NI)活性的峰值期均出现在果实老化前。综上所述,纤维素含量不断增加是影响黄秋葵果实老化的主要因素,CesA、Kor和β-GC为参与纤维素代谢的关键酶类,蔗糖代谢酶参与了黄秋葵果实的成熟老化过程。

The fruits of two okra(Abelmoschus esculentus L.)varieties,Kariba and Youlü1,were used as experimental materials to determine the changes of cell wall composition,sugar accumulation and related enzyme activities during fruit development.The correlation between cellulose content and the activities of enzymes related to cellulose metabolism was analyzed.The results showed that the suitable harvest time of the two varieties of okra was 6-7 days after anthesis.During the fruit development,the contents of lignin and hemicellulose increased first and then decreased,the content of cellulose increased continuously,the activities of cellulase synthase(CesA)and korrigan(Kor)increased,the activities of sucrose synthase(SS-I),endo-β-1,4-glucanase(Cx)and exo-β-1,4-glucanase(C1)increased first and then decreased,and the activity of β-glucosidase(β-GC)decreased continuously.The contents of lignin,hemicellulose,cellulose and the activities of enzymes related to cellulose metabolism in Kariba fruit were higher than those in Youlü1.The results of correlation analysis showed that the activities of CesA and Kor were positively correlated with the content of cellulose,and the activity ofβ-GC was negatively correlated with the content of cellulose.The results of sugar content determination indicated that the content of sucrose in the fruits of the two varieties showed an upward trend,the contents of fructose and glucose reached the peak values at six days after anthesis,and the activities of sucrose phosphate synthase(SPS)and invertase(SAI,BAI,NI)reached the peak values before fruit aging.In conclusion,the increasing cellulose content was the main factor affecting the aging of okra fruit.CesA,Kor andβ-GC were the key enzymes involved in the metabolism of cellulose,and sucrose metabolism was involved in the aging of okra fruit.