Comparative Proteome-wide Characterization of Three Different Tissues of High-Protein Mutant and Wild Type Unravels Protein Accumulation Mechanisms in Rice Seeds

Improving the proteins and amino acid contents of riceseeds isone of the prime objectives of plant breeders. We recently developedan EMS mutant/high-protein mutant (HPM) of rice that exhibits 14.8%of the total protein content as compared to its parent Dharial (wild-type),which shows only 9.3% protein content in their mature seeds. However,the mechanisms underlying the higher protein accumulation in theseHPM seeds remain largely elusive. Here, we utilized high-throughputproteomics to examine the differences in the proteome profiles ofthe embryo, endosperm, and bran tissues of Dharial and HPM seeds.Utilizing a label-free quantitative proteomic and subsequent functionalanalyses of the identified proteins revealed that nitrogen compoundbiosynthesis, intracellular transport, protein/amino acid synthesis,and photosynthesis-related proteins were specifically enriched inthe endosperm and bran of the high-protein mutant seed. Our data haveuncovered proteome-wide changes highlighting various functions ofmetabolic pathways associated with protein accumulation in rice seeds.