Identification of Late Flavonoid Biosynthesis Genes of Moso Bamboo Reveals the Potential Function of PeANR4 Involved in Osmotic and Salt Stress

Abstract

Flavonoids are important secondary metabolites in plants, and their biosynthesis includes various enzymes. Although bamboo is a potential resource with abundant flavonoids, its flavonoids biosynthesis is still unclear. Based on the genome and transcriptome data of moso bamboo (Phyllostachys edulis), 24 late flavonoid biosynthesis genes (LFBGs) were identified. Further molecular characteristics analyses suggested they may have different biological functions in flavonoids biosynthesis. Sixteen differentially expressed genes were identified according to transcriptome data from different-height shoots, including five PeANSs, four PeANRs, three PeLARs, and PeDFR1. PeANR4 expressed continuously under drought stress was selected for further analysis. A co-expression network of PeANR4 and 27 differentially expressed transcription factors (DETFs) was constructed, and the regulatory relationship of four DETFs and PeANR4 was validated by Y1H assays. Furthermore, PeANR4 was ectopically expressed in Arabidopsis, and the transgenic lines had darker seed coat color and higher fresh, dry weight and proanthocyanidin (PA) content than the wild type and mutant. Moreover, the transgenic lines had higher germination rate and longer primary root than the wild type and mutant under osmotic and salt stress. These results provide a full understanding and lay a foundation for further functional studies on the LFBGs of bamboo.