Informal Seminar - Hong Ma

Abstract:

RNA splicing is crucial for gene expression and its regulation; however, relatively little is known about factors and mechanisms regulating plant RNA splicing. At the same time, the great majority of genes revealed by plant genomics lack known functions, defined either genetically or biochemically. To identify novel gene functions important for regulation of reproductive gene expression, we used omics and functional analyses to identify a novel factor, GRP20, for proper floral RNA splicing and characterized its mechanisms as a newly uncovered RNA-binding protein. GRP20 is required for normal floral organ development and floral RNA splicing, especially the proper retention of micro exons in floral homeotic ABCE genes. Thousands of micro exons are found in each of diverse plants and in genes of a variety of functions, present in genes with different exon-intron organizations and encode portions of a wide spectrum of protein domains with different annotated functions. Many micro exons can be skipped in alternative transcripts and their length in multiple of 3 nucleotides suggest that alternative splicing of these micro exons could lead to the production of protein isoforms with varying activities. Profiling of these gene structure and protein domain organizations across angiosperms suggests high degrees of conservation, while micro exon-related changes have occurred in specific lineages. Both the functional and evolutionary genomic analyses highlight the great need to probe gene functions at multiple levels, including transcriptional and post-transcriptional, to gain further understanding of gene regulation.