Studies on the Relationship between Fruit Aging Mechanism and Endoglucanase Gene Family of Hibiscus esculentus L.
LI Yongping1, CHEN Chaowen2, MA Huifei1, KANG Yumei1, BAI Changhui1, XUE Zhuzheng1*, WEN Qingfan1*
Hibiscus esculentus L. is very easy to age, and its harvest time and shelf life are very short. In order to study the aging mechanism of Hibiscus esculentus L. fruit, the changes of cellulose content as well as the cell cellulose structure were analysed during the fruit development and the postharvest period. It was found that in the aging process of Hibiscus esculentus L. fruit, both the content of cellulose and the cell cellulose tissue were increased. It was suggested that the increase of cellulose was the leading factor of the Hibiscus esculentus L. fruit aging. Endoglucanase genes in plants are closely related to cellulose synthesis. In this study, seven fragments which were functionally annotated as endoglucanase gene family were screened from the RNA-seq database of Hibiscus esculentus L. fruit transcriptome sequencing, and 7 full-length genes of endoglucanase gene family, endoglucanase1, endoglucanase3, endoglucanase6, endoglucanase10, endoglucanase11, endoglucanase23 and endoglucanas25 were cloned and named as HeCEL1, HeCEL3, HeCEL6, HeCEL10, HeCEL11, HeCEL23 and HeCEL25 respectively. All these genes belong to the GH9 family. Expression patterns of the these genes were carried out by qRTPCR (reverse transcript qunntitative PCR). It showed that expression patterns of HeCEL3, HeCEL10 and HeCEL25 were in the same, and HECEL6 was in concordance with HeCEL23, too. The expression of HeCEL25 was stable at 0-2 days after harvest, while the expression of the other 6 genes decreased sharply at 1 day after harvest. During the development of Hibiscus esculentus L. fruit, the content of cellulose stored at room temperature after harvest was significantly negatively correlated with the expression of HeCEL3, HeCEL10, HeCEL25, HeCEL6 and HeCEL23, and it was speculated that HeCEL3, HeCEL10, HeCEL25, HeCEL6 and HeCEL23 played an important role in cellulose accumulation in Hibiscus esculentus L. fruit, which was closely related to the aging of Hibiscus esculentus L. fruit.
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