Comprehensive metabolome and transcriptome analyses demonstrate divergent anthocyanin and carotenoid accumulation in fruits of wild and cultivated loquats

Abstract

Eriobotrya is an evergreen fruit tree native to South-West China and adjacent countries. There are more than 26 loquat species known in this genus, while E. japonica is the only species yet domesticated to produce fresh fruits from late spring to early summer. Fruits of cultivated loquat are usually orange colored, in contrast to the red color of fruits of wild E. henryi (EH). However, the mechanisms of fruit pigment formation during loquat evolution are yet to be elucidated. To understand these, targeted carotenoid and anthocyanin metabolomics as well as transcriptomics analyses were carried out in this study. The results showed that β-carotene, violaxanthin palmitate and rubixanthin laurate, totally accounted for over 60% of the colored carotenoids, were the major carotenoids in peel of the orange colored ‘Jiefangzhong’ (JFZ) fruits. Total carotenoids content in JFZ is about 10 times to that of EH, and the expression levels of PSY, ZDS and ZEP in JFZ were 10.69 to 23.26 folds to that in EH at ripen stage. Cyanidin-3-O-galactoside and pelargonidin-3-O-galactoside were the predominant anthocyanins enriched in EH peel. On the contrary, both of them were almost undetectable in JFZ, and the transcript levels of F3H, F3’H, ANS, CHS and CHI in EH were 4.39 to 73.12 folds higher than that in JFZ during fruit pigmentation. In summary, abundant carotenoid deposition in JFZ peel is well correlated with the strong expression of PSY, ZDS and ZEP, while the accumulation of anthocyanin metabolites in EH peel is tightly associated with the notably upregulated expressions of F3H, F3’H, ANS, CHS and CHI. This study was the first to demonstrate the metabolic background of how fruit pigmentations evolved from wild to cultivated loquat species, and provided gene targets for further breeding of more colorful loquat fruits via manipulation of carotenoids and anthocyanin biosynthesis.

Multi-omics analysis provides new insights into the changes of important nutrients and fructose metabolism in loquat bud sport mutant

“…In fact, carotenoids also belong to terpenoids, and there have been extensive studies on the relationship between the carotenoid and flavonoid biosynthesis pathways. A recent study on the pigments of wild loquats and cultivated varieties has demonstrated that the content of carotenoids and flavonoids in the flesh displays a significant opposing trend in the process of evolution, indicating a potential metabolic flux in the fruit ( Su et al., 2023 ). Analogously, the flavonoid and carotenoid biosynthetic pathways affect fruit quality by competing for metabolic flux in SlPSY1 loss-of-function mutants of tomato ( Cao et al., 2023 ), which is the same as the effect of PSY2A deletion in TBW in our previous study ( Song et al., 2022b ).…”

Metabolome integrated with transcriptome reveals the mechanism of three different color formations in Taxus mairei arils

“…Carotenoids, including lycopene and a range of alpha, beta, gamma, and delta carotenoids, undergo synthesis from isoprenoids (IPPs) via enzymatic catalysis. The accumulation of beta-carotene, violaxanthin palmitate, and rubixanthin laurate in Eriobotrya was regulated by the phytoene synthase ( PSY ), Zeta-carotene desaturase ( ZDS ), and zeta-carotene isomerase ( ZEP ) genes ( Su et al., 2023 ). The PSY , Lycopene cyclase/phytoene synthase ( LCYE ), and ZDS were the key genes that regulated the lycopene accumulation of Persimmon fruits ( Ye et al., 2022 ).…”