Genome-wide characterization, identification, and function analysis of candidate JsMYB genes involved in regulating flavonol biosynthesis in Juglans sigillata Dode

Juglans sigillata Dode is a unique walnut population that originated from China and is rich in flavonol. MYB transcription factors (TFs) are the main regulator of flavonol biosynthesis. It is necessary to conduct a genome-wide analysis of MYB TFs and identify members that regulate flavonols synthesis in J. sigillata Dode. We identified 222 JsMYBs genes and made a series of bioinformatics analyses on them. Phylogenetic analysis suggested that JsMYB121, JsMYB141, JsMYB148 and JsMYB170 encoded orthologs of AtMYB11, AtMYB12 and AtMYB111 which regulated flavonol synthesis in Arabidopsis. According to the results of correlation analysis, overexpression in calli and silence in green husks, we found that JsMYB121 negatively regulated flavonoid synthesis, JsMYB148 slightly regulated flavonol synthesis, and JsMYB141 and JsMYB170 were the main regulators of flavonol synthesis in J. sigillata fruit. JsMYB141 positively regulated the expression levels of JsPAL, JsCHS, JsF3′H and JsFLS to improve the contents of myricetin and rutin. And JsMYB170 positively regulated the expression levels of JsCHS, JsCHI, JsFLS and JsDFR to increase the contents of quercetin, kaempferol and rutin. Our study provided a comprehensive understanding of the JsMYBs gene family and identified JsMYBs regulating flavonol biosynthesis in J. sigillata.