Two RuEGs regulates blackberry fruit firmness by effecting the genes of cell wall at different ripening stages

Abstract

Abstract As a new generation of economically important fruit, blackberry fruit is rich in nutrients and functional components. However, the ripe fruit is very low in firmness, soft, and perishable. Therefore, storage and preservation have become important factors restricting its industrial development. This study introduced overexpression vectors of RuEG1 and RuEG2 from blackberry into tomato, and showed that firmness of transgenic tomato fruit decreased with the development period. The structure of transgenic tomato collapsed earlier than that of wild-type tomato. Comparison showed that the contents of cellulose, hemicellulose, and pectin in transgenic tomato were significantly reduced compared with wild-type tomato. Activities of pectin methylesterase and cellulase were significantly increased in transgenic compared with wild-type tomato. Transcriptome and qRT-PCR data showed that the expression levels of cell wall degrading enzyme genes XTH3, Cel2 and Cel8 were significantly higher than those of the control. The results showed that RuEG1 and RuEG2 regulated enzyme activity in fruit cell walls and influenced cell wall composition, thus regulating fruit firmness and improving fruit quality and storability. In addition, the XTH3 and Cel8 were highly expressed in RuEG2 transgenic fruits and higher than those in RuEG1 might be the reason why they play a role in different fruit ripening stages.