Identification of the walnut CHS and FLS gene families and the role of JrHY5 in flavonoid synthesis
Zhongrong Zhang, Xing Yuan, Jin‐Ming Liu, Caihua Guo, Chao Kang, Xia Luo, Haochang Zhao, Shaowen Quan, Jianxin Niu
Abstract
Walnut ( Juglans regia L.) is a deciduous tree belonging to the family Juglandaceae and is widely cultivated around the world. It is rich in flavonoids, phenolic compounds, and oils, and has significant industrial value and economic benefits. However, the identification of walnut CHS and FLS gene families and the regulation of walnut flavonoid synthesis by JrHY5 ( ELONGATED HYPOCOTYL 5 ) have not been reported yet. Therefore, we identified 17 CHS/FLS genes in the walnut genome, grouping them into four subfamilies with conserved motifs and similar structures. Promoters are rich in light and hormone response elements, gene expansion occurs primarily through fragment duplication. The vast majority of CHS and FLS genes are highly expressed mainly in vegetative buds, female flowers, and mature leaves, and their expression is induced by cold stress and Colletotrichum gloeosporioides infection. LUC assays demonstrated that JrHY5 binds to the promoters of JrCHS6 and JrFLS3. Silencing of the JrHY5 gene reduced the flavonoid content and the expression of related genes, and JrHY5 transgenic tobacco accumulated more flavonoids. Our study systematically analyzed the walnut CHS and FLS gene families and resolved the function of JrHY5 in the synthesis of walnut flavonoids, which is beneficial for the genetic improvement of walnut. • We identified 10 CHS genes and 7 FLS genes in the walnut genome and analyzed them systematically. • Walnut CHS and FLS genes are highly expressed in buds, female flowers and mature leaves. • JrHY5 is involved in flavonoid biosynthesis by regulating JrCHS6 and JrFLS3. • JrHY5 increased flavonoid content in Juglans regia and Nicotiana tabacum .