Transcriptome changes associated with boron applications in fruits of watercore-susceptible pear cultivar

Watercore is a common physiological disorder in pear and is closely related to the excessive accumulation of sorbitol and sucrose. Our previous research found that the incidence of watercore in 'Akibae' (Pyrus pyrifolia cv. Akibae) fruit significantly decreased after boron application (BA). Moreover, the foliar spray of boric acid also significantly improved fruit quality. However, the mechanisms underlying the pear fruit response to BA was still limited.

A comprehensive transcriptome analysis of BA treatment 'Akibae' pear fruit was performed in this study. Transcriptome results revealed a total of 3146 up-regulated and 1145 down-regulated differentially expressed genes (DEGs) between control and treated fruits of 'Akibae' pear. BA significantly induced the expression of sorbitol metabolism and sucrose metabolism genes. In addition, BA also increased the expression of starch degradation, fatty acid synthesis, IAA (indole-3-acetic acid) degradation, and GA (gibberellin acid) synthesis genes and inhibited the expression of ethylene synthesis genes.

These findings suggested that BA probably alleviates 'Akibae' watercore occurrence and improves fruit quality by regulating the decrease in sorbitol and sucrose, the increase in fatty acids and the balance of plant hormones. Our results provide further information for understanding the molecular mechanism of the effect of BA on pear fruit.