Transcriptome and metabolome analyses of Bartlett and Xiang shuomi pear (Pyrus communis L.) unveiled the candidate genes and pathways regulating leaf and fruit size
The size of leave and fruits was a crucial agronomic and economic trait for fruit trees. Bartlett pear is a famous cultivar with succulent and delicious fruit and cultivated globally. Xiangshuomi is a bud sport of Bartlett pear, discovered in our breeding work and exhibits enlarged leaf and fruit. However, the specific regulatory mechanism of the superior agronomic trait is still elusive. In this study, we performed comprehensive transcriptome and metabolome analyses to explore the differences in gene expression and metabolite accumulation between the two pear cultivars. Transcriptome analysis showed a total of 1279 differentially expressed genes (DEGs), with the flavonoid biosynthetic process being the most significant enriched biological process. Metabolome data indicated the detection of 412 differentially abundant metabolites (DAMs), the metabolites of flavone and flavonol biosynthesis and flavonoid biosynthesis being enriched significantly. The integrative transcriptomic and metabolomics analysis further confirmed the pivotal role of flavonoid biosynthetic process in distinguishing the two cultivars. Importantly, the genes encoding enzymes involved in flavonoid biosynthesis, including CHS, CHI, HCT, LAR and CYP75B1, increased their expressions in Xiangshuomi pear. Correspondingly, the metabolites galangin, chlorogenic acid, luteolin and catechin were found to accumulate in Xiangshuomi pear. Overall, this research identified key pathways and genes influencing fruit and leaf size of pear, providing the fundamental information for the high-yield breeding of fruit trees.