Unveiling distinct storage composition and starch properties in developing indica rice grains via transcriptional profiling and enzymatic activity analysis
Recently, we observed significant differences in the starch molecular composition and structure between the two Thai indica rice cultivars, RD6 and RD57. However, a comprehensive understanding of the transcriptional regulation of their storage polymers, remains lacking. To address this, we investigated the gene expression patterns and enzymatic activities of key starch and storage protein biosynthetic enzymes in the developing endosperms of these cultivars. The transcriptional profiles of waxy RD6 and high-amylose RD57 rice endosperms were analyzed at 7, 14, 21, and 28 days post-anthesis (DPA). The expression patterns of major differentially expressed genes (DEGs) were cross validated with enzymatic activities and the grain starch and storage protein compositions. Gene expression profiles varied significantly between the RD6 and RD57 rice cultivars, with the most distinct differences observed at 14 days post-anthesis (DPA) and the least at 28 DPA. Temporal dynamics of transcriptome profiles among genes in starch and storage protein biosynthesis revealed active gene expression at 14 DPA and 7 DPA. Collectively, this study provided a comprehensive understanding of the biosynthesis of storage biomolecules through transcriptional profiling of the Thai indica rice. For the breeding and developing new Thai commercial rice varieties with targeted ECQ and health-beneficial traits, understanding the regulatory mechanisms that control starch and storage protein accumulation at both transcriptional and post-translational levels is crucial. Overall design: RNA-seq profiling of waxy RD6 and high-amylose RD57 rice endosperms at 7, 14, 21, and 28 days post-anthesis (DPA)