Integrative Analysis of Metabolome and Transcriptome Reveals the Mechanism of Color Formation in Actinidia Chinensis Fruit

In order to understand the mechanism of flesh color transformation, we conducted comprehensive metabolome and transcriptome analysis of kiwifruit flesh. A total of 139 flavonoids were identified, and 76% of the flavonoids accumulated in large amounts on the 20 d, which was related to the decreased expression of the phenylalanine ammonia lyase ( PAL ). Using gene co-expression network analysis, we identified modules related to flavonoid synthesis and candidate transcription factors regulating flavonoid synthesis and transport. The β -cryptoxanthin increased rapidly at 136 d and reached the highest content at 175 d, which was significantly higher than other carotenoids, which was related to the differences in the expression of cyclase genes in the branch of metabolic pathways. Two candidate transcription factors were screened to be involved in carotenoid synthesis or transport by WGCNA. Our findings provide new insights into the synthesis and accumulation of flavonoids and carotenoids in yellow-fleshed kiwifruit.