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 rice
seeds is
one of the prime objectives of plant breeders. We recently developed
an 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 these
HPM seeds remain largely elusive. Here, we utilized high-throughput
proteomics to examine the differences in the proteome profiles of
the embryo, endosperm, and bran tissues of Dharial and HPM seeds.
Utilizing a label-free quantitative proteomic and subsequent functional
analyses of the identified proteins revealed that nitrogen compound
biosynthesis, intracellular transport, protein/amino acid synthesis,
and photosynthesis-related proteins were specifically enriched in
the endosperm and bran of the high-protein mutant seed. Our data have
uncovered proteome-wide changes highlighting various functions of
metabolic pathways associated with protein accumulation in rice seeds.