Poster abstracts
Poster number 24 submitted by Manohar Chakrabarti
A genome-wide alternative polyadenylation and gene expression analysis provides molecular insights into the abiotic stress response in sorghum
Manohar Chakrabarti (Dept. of Plant and Soil Sciences, University of Kentucky ), Laura de Lorenzo (Dept. of Plant and Soil Sciences, University of Kentucky ), Salah E. Abdel-Ghany (Department of Biology, Colorado State University), Anireddy S.N. Reddy (Department of Biology, Colorado State University), Arthur G. Hunt (Dept. of Plant and Soil Sciences, University of Kentucky )
Abstract:
Sorghum [Sorghum bicolor (L.) Moench] is a major cereal and bioenergy crop and is grown widely in some of the harshest agro-climatic regions in the world, such as in South Asia and Sub-Saharan Africa. In spite of its importance, not much is known about the transcriptional and post-transcriptional regulation of abiotic stress responses in sorghum. Recent studies have unearthed the role of alternative polyadenylation (APA) in diverse developmental and physiological processes by virtue of its effects on gene expression, mRNA stability, translatability and subcellular localization. Under this backdrop, we have undertaken a genome-wide APA and gene expression analysis in sorghum seedlings that have been subjected to several abiotic stresses. The genome-wide APA analysis revealed that under different stress treatments, the relative levels of mRNA isoforms derived from APA at locations within protein-coding regions and 5΄UTRs increased significantly, and isoforms derived from polyadenylation within introns increased slightly. Conversely, the levels of mRNA isoforms with poly (A) sites in annotated 3΄-UTRs decreased significantly in stressed plants compared with controls. Our analysis also identified poly (A) clusters and genes depicting APA under abiotic stresses. A comparison of gene expression analysis using PATs, mapped to the ‘gene’ with those mapped only to the ‘3΄UTR’, suggested that there can be false positives among the differentially expressed genes from the ‘gene’ dataset, which led us to perform gene expression analysis with the PATs, mapped only to the ‘3΄UTR’ to generate a catalog of functional gene expression. The gene expression analysis revealed that sorghum responds faster to the salinity and heat stress as compared to the drought stress, however, at prolonged exposure all three stresses impacted gene expression significantly. Interestingly, prolonged drought and salt treatments led to a significant down regulation of several core histone genes. Altogether, these analyses suggested a novel possible mode of epigenetic control of abiotic stress responses, and they also revealed a widespread role for APA in regulating abiotic stress responses in this important cereal crop.
Keywords: Sorghum, abiotic stress, alternative polyadenylation