title: Genome-wide survey on genomic variation, expression divergence, and evolution in two contrasting rice genotypes under high salinity stress.
abstract: Expression profiling is one of the most important tools for dissecting biological functions of genes and the upregulation or downregulation of gene expression is sufficient for recreating phenotypic differences. Expression divergence of genes significantly contributes to phenotypic variations. However, little is known on the molecular basis of expression divergence and evolution among rice genotypes with contrasting phenotypes. In this study, we have implemented an integrative approach using bioinformatics and experimental analyses to provide insights into genomic variation, expression divergence, and evolution between salinity-sensitive rice variety Nipponbare and tolerant rice line Pokkali under normal and high salinity stress conditions. We have detected thousands of differentially expressed genes between these two genotypes and thousands of up- or downregulated genes under high salinity stress. Many genes were first detected with expression evidence using custom microarray analysis. Some gene families were preferentially regulated by high salinity stress and might play key roles in stress-responsive biological processes. Genomic variations in promoter regions resulted from single nucleotide polymorphisms, indels (1-10 bp of insertion/deletion), and structural variations significantly contributed to the expression divergence and regulation. Our data also showed that tandem and segmental duplication, CACTA and hAT elements played roles in the evolution of gene expression divergence and regulation between these two contrasting genotypes under normal or high salinity stress conditions.
authors.affiliation: Temasek Life Sciences Laboratory, National University of Singapore, Singapore.
authors.forename: Shu-Ye
authors.initials: SY
authors.lastname: Jiang
authors.forename: Ali
authors.initials: A
authors.lastname: Ma
authors.forename: Rengasamy
authors.initials: R
authors.lastname: Ramamoorthy
authors.forename: Srinivasan
authors.initials: S
authors.lastname: Ramachandran
mesh_terms: D019143:Evolution, Molecular; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D005838:Genotype; D054643:INDEL Mutation; D012275:Oryza / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide; D054712:Salinity; D056916:Segmental Duplications, Genomic; D013312:Stress, Physiological; D020080:Tandem Repeat Sequences; D014158:Transcription, Genetic
chemical_list: D010940:Plant Proteins
keywords: custom microarray; gene set enrichment analysis; promoter motif; single nucleotide polymorphism; tandem and segmental duplication; transposition