The rice EP3 and OsFBK1 E3 ligases alter plant architecture and flower development, and affect transcript accumulation of microRNA pathway genes and their targets

Understanding the evolution of miRNA biogenesis machinery in plants with special focus on rice

miRNA biogenesis process is an intricate and complex event consisting of many proteins working in a highly coordinated fashion. Most of these proteins have been studied in Arabidopsis; however, their orthologs and functions have not been explored in other plant species. In the present study, we have manually curated all the experimentally verified information present in the literature regarding these proteins and found a total of 98 genes involved in miRNA biogenesis in Arabidopsis. The conservation pattern of these proteins was identified in other plant species ranging from dicots to lower organisms, and we found that a major proportion of proteins involved in the pri-miRNA processing are conserved. However, nearly 20% of the genes, mostly involved in either transcription or functioning of the miRNAs, were absent in the lower organisms. Further, we manually curated a regulatory network of the core components of the biogenesis process and found that nearly half (46%) of the proteins interact with them, indicating that the processing step is perhaps the most under surveillance/regulation. We have subsequently attempted to characterize the orthologs identified in Oryza sativa, on the basis of transcriptome and epigenetic modifications under field drought conditions in order to assess the impact of drought on the process. We found several participating genes to be differentially expressed and/or epigenetically methylated under drought, although the core components like DCL1, SE, and HYL1 remain unaffected by the stress itself. The study enhances our present understanding of the biogenesis process and its regulation.

Identification of KFB Family in Moso Bamboo Reveals the Potential Function of PeKFB9 Involved in Stress Response and Lignin Polymerization

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.