Yan Liu

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.

The Kelch repeat F-box (KFB) protein is an important E3 ubiquitin ligase that has been demonstrated to perform an important post-translational regulatory role in plants by mediating multiple biological processes. Despite their importance, KFBs have not yet been identified and characterized in bamboo. In this study, 19 PeKFBs were identified with F-box and Kelch domains; genes encoding these PeKFBs were unevenly distributed across 12 chromosomes of moso bamboo. Phylogenetic analysis indicated that the PeKFBs were divided into eight subclades based on similar gene structures and highly conserved motifs. A tissue-specific gene expression analysis showed that the PeKFBs were differentially expressed in various tissues of moso bamboo. All the promoters of the PeKFBs contained stress-related cis-elements, which was supported by the differentially expression of PeKFBs of moso bamboo under drought and cold stresses. Sixteen proteins were screened from the moso bamboo shoots’ cDNA library using PeKFB9 as a bait through a yeast two-hybrid (Y2H) assay. Moreover, PeKFB9 physically interacted with PeSKP1-like-1 and PePRX72-1, which mediated the activity of peroxidase in proteolytic turnover. Taken together, these findings improved our understanding of PeKFBs, especially in response to stresses, and laid a foundation for revealing the molecular mechanism of PeKFB9 in regulating lignin polymerization by degrading peroxidase.

The 14-3-3 protein family plays an important role in regulating plant growth and development. The genes of the 14-3-3 family have been reported in multiple species. However, little is known about the 14-3-3 gene family in bamboo. In this study, a total of 58 genes belonging to the 14-3-3 family were identified in three representative bamboo species, i.e., Olyra latifolia, Phyllostachys edulis, and Bonia amplexicaulis, whose encoding proteins were grouped into ε and non-ε groups by phylogeny analysis with 14-3-3 proteins from Arabidopsis thaliana and Oryza sativa. The 14-3-3s had diverse gene structures and motif characteristics among the three bamboo species. Collinearity analysis suggested that the genes of the 14-3-3 family in bamboo had undergone a strong purification selection during evolution. Tissue-specific expression analysis showed the expression of Pe14-3-3s varied in different tissues of P. edulis, suggesting that they had functional diversity during growth and development. Co-expression analysis showed that four Pe14-3-3s co-expressed positively with eight ribosomal genes. Yeast two-hybrid (Y2H) assays showed that Pe14-3-3b/d could interact with Pe_ribosome-1/5/6, and qPCR results demonstrated that Pe14-3-3b/d and Pe_ribosome-1/5/6 had similar expression trends with the increase in shoot height, which further confirmed that they would work together to participate in the shoot growth and development of bamboo. Additionally, the transgenic Arabidopsis plants overexpressing Pe14-3-3b had longer roots, a larger stem diameter, an earlier bolting time and a faster growth rate than wild-type Arabidopsis, indicating that Pe14-3-3b acted as a growth promoter. Our results provide comprehensive information on 14-3-3 genes in bamboo and highlight Pe14-3-3b as a potential target for bamboo improvement.

Simple sequence repeats (SSRs) are one of the most important molecular markers, which are widespread in plants. Bamboos are important forest resources worldwide. Here, the comprehensive identification and comparative analysis of SSRs were performed in three woody and two herbaceous bamboo species. Altogether 567,175 perfect SSRs and 71,141 compound SSRs were identified from 5737.8 Mb genome sequences of five bamboo species. Di-nucleotide SSRs were the most predominant type, with an average of ~50,152.2 per species. Most SSRs were located in intergenic regions, while those located in genic regions were relatively less. Moreover, the results of annotation distribution indicated that terms with P450, peroxidase and ATP-binding cassette transporter related to lignin biosynthesis might play important roles in woody and herbaceous bamboos under the mediation of SSRs. Furthermore, the peroxidase gene family consisted of a large number of genes containing SSRs was selected for the evolutionary relationship analysis and SSR markers development. Fifteen SSR markers derived from peroxidase family genes of Phyllostachys edulis were identified as polymorphic in 34 accessions belonging to seven genera in Bambusoideae. These results provided a comprehensive insight of SSR markers into bamboo genomes, which would facilitate bamboo research related to comparative genomics, evolution and marker-assisted selection.