Integrated transcriptome and metabolome analysis unveiled the mechanisms of xenia effect and the role of different pollens on aroma formation in ‘Yali’ pear (Pyrus bretschneideri Rehd)

Abstract

• ‘Hongnanguo’ pollinizer has a xenia effect on ‘Yali’ pear fruits aroma quality. • 189 DAMs and 12,032 DEGs were identified. • ‘Hongnanguo’ pollinizer increased the content of ABA, IAA, and ethylene. • Established a possible regulatory network of the mechanism of xenia effect on pear aroma formation. The flavor of ‘Yali’ pear fruits has substantially declined recently as a result of poor pollination tree selection. Xenia effect is a powerful mechanism for regulating aroma production. To study the effect of different pollens on aroma quality and the molecular basis of xenia effect in ‘Yali’ pear fruits, ‘Hongnanguo’ and ‘Xuehuali’ were used as pollinizers, and the hybrid fruits were named YH and YX, respectively. Metabolome, transcriptome, volatile compounds, and hormone were jointly analyzed in YH and YX peels with three ripening stages. After pollinating with ‘Hongnanguo’ pollen, the contents of total aroma, esters and nerolidol, the odor activity value of characteristic volatiles in YH were significantly increased, compared with the aroma character of the pollinizer cultivars, indicating ‘Hongnanguo’ pollinizer has a xenia effect on ‘Yali’ pear fruits aroma quality. Further, the content of ABA, IAA, and ethylene reveal the differences during aroma formation between YH and YX. 189 differentially accumulated metabolites (DAMs) and 12,032 differentially expressed genes (DEGs) were identified. Based on co-expression network analysis, network maps of ‘Yali’ pear aroma-related DEGs were generated. We surmise aroma biosynthesis genes ( ADH, ALDH, NES , and FPS ), ABA, IAA, ethylene signal transduction, and several transcription factors play important roles in the xenia effect.