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SlMYB72 Regulates the Metabolism of Chlorophylls, Carotenoids, and Flavonoids in Tomato Fruit
Author(s) -
Mengbo Wu,
Xin Xu,
Xiaowei Hu,
Yudong Liu,
Haohao Cao,
Helen M. Chan,
Zehao Gong,
Yujin Yuan,
Yingqing Luo,
Bihong Feng,
Zhengguo Li,
Wei Deng
Publication year - 2020
Publication title -
plant physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.554
H-Index - 312
eISSN - 1532-2548
pISSN - 0032-0889
DOI - 10.1104/pp.20.00156
Subject(s) - phytoene synthase , chalcone synthase , chromoplast , biochemistry , carotenoid , flavonoid biosynthesis , biology , chloroplast , lycopene , ripening , phytoene desaturase , chalcone isomerase , chlorophyll , myb , solanum , biosynthesis , gene expression , gene , botany , plastid , transcriptome
Tomato ( Solanum lycopersicum ) fruit ripening is accompanied by the degradation of chlorophylls and the accumulation of carotenoids and flavonoids. Tomato SlMYB72 belongs to the R2R3 MYB subfamily, is located in the nucleus, and possesses transcriptional activator activity. Down-regulation of the SlMYB72 gene produced uneven-colored fruits; that is, dark green spots appeared on immature and mature green fruits, whereas yellow spots appeared on red fruits. Down-regulation of SlMYB72 increased chlorophyll accumulation, chloroplast biogenesis and development, and photosynthesis rate in fruits. This down-regulation decreased lycopene content, promoted β-carotene production and chromoplast development, and increased flavonoid accumulation in fruits. RNA sequencing analysis revealed that down-regulation of SlMYB72 altered the expression levels of genes involved in the biosynthesis of chlorophylls, carotenoids, and flavonoids. SlMYB72 protein interacted with the auxin response factor SlARF4. SlMYB72 directly targeted protochlorophyllide reductase, Mg-chelatase H subunit, and knotted1-like homeobox2 genes and regulated chlorophyll biosynthesis and chloroplast development. SlMYB72 directly bound to phytoene synthase, ζ-carotene isomerase, and lycopene β-cyclase genes and regulated carotenoid biosynthesis. SlMYB72 directly targeted 4-coumarate-coenzyme A ligase and chalcone synthase genes and regulated the biosynthesis of flavonoids and phenolic acid. The uneven color phenotype in RNA interference-SlMYB72 fruits was due to uneven silencing of SlMYB72 and uneven expression of chlorophyll, carotenoid, and flavonoid biosynthesis genes. In summary, this study identified important roles for SlMYB72 in the regulation of chlorophyll, carotenoid, and flavonoid metabolism and provided a potential target to improve fruit nutrition in horticultural crops.

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