The regulation of flavonoid biosynthesis is only partially explored in pepper (Capsicum annuum L.). The genetic basis underlying flavonoid variation in pepper fruit was studied. Variation of flavonoids in fruit of a segregating F2 population was studied using LC-MS followed by quantitative trait locus (QTL) analysis. Near-isogenic lines (NILs), BC1 S1 populations, virus-induced gene silenced (VIGS) and transgenic overexpression were used to confirm the QTL and the underlying candidate gene. A major QTL for flavonoid content was found in chromosome 5, and a CaMYB12-like transcription factor gene was identified as candidate gene. Near-isogenic lines (NILs) contrasting for CaMYB12-like confirmed its association with the flavonoid content variation. Virus-induced gene silencing (VIGS) of CaMYB12-like led to a significant decrease in the expression of several flavonoid pathway genes and a drastic decrease in flavonoid levels in silenced fruits. Expression of CaMYB12-like in the tomato slmyb12 mutant led to enhanced levels of several flavonoids in the fruit skin. Introgression of the CaMYB12-like allele into two cultivated varieties also increased flavonoid content in their fruits. A combination of metabolomic, genetic and gene functional analyses led to discovery of CaMYB12-like as a major regulator of flavonoid variation in pepper fruit and demonstrated its potential to breed for high-flavonoid content in cultivated pepper.
Keywords: CaMYB12-like; breeding; capsicum; flavonoids; health-related compounds; quantitative trait locus (QTL) transcription factor.
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