Transcriptome Analysis of Oryza sativa (Rice) Seed Germination at High Temperature Shows Dynamics of Genome Expression Associated with Hormones Signalling and Abiotic Stress Pathways

Abstract

Seed germination directly affects growth and yield of rice. Germination process is highly dependent on temperature which regulates expression of several genes and proteins in germinating tissue. Whole genome mRNA sequencing of rice germinated at optimum (30 °C) and high temperature (42 °C) was performed using Ion Torrent Sequencing. Bioinformatics analysis of sequence data was done to survey the expressed genes, gene ontology, and pathway analysis. High temperature altered the expression of genes involved in fatty acid, amino acid, carbohydrate, and energy metabolism. Genes involved in reserve degradation, protein folding and stress responses were also significantly affected. Induced expression of genes like dehydration responsive element binding (DREB), RAB (responsive to ABA), and late embryogenesis abundant (LEA) proteins suggested important role of these proteins in high temperature germinated (HTG) rice. The pathway analysis of differentially expressed genes at high temperature suggested the altered expression of transcripts associated with ABA and jasmonate signalling, antioxidants (peroxidase and ascorbate peroxidase), heat shock proteins (HSP 20 and HSP70 family), heat shock protein binding protein1 (HSPBP1, HSP70-interacting protein) and other stress associated pathways. In present scenario where very limited information is available on genome wide transcripts expression during germination process, the transcriptome study done in rice provides an opportunity to better understand the genes expression and regulation of seed germination, which is highly influenced by temperature.