Seed vigor is an imperative trait for the direct seeding of rice.
Isopropylmalate synthase (IPMS) is known to catalyze an important step in
leucine (Leu) synthesis, but its effect on seed vigor remains unclear.
Nanjing Agricultural University researchers led by Yongqi He investigated
the role of rice OsIPMS1 and OsIPMS2 genes in seed vigor.
Both OsIPMS1 and OsIPMS2 catalyze Leu synthesis, and Leu feedback inhibits
their activities. Disruption of OsIPMS1 via CRISPR-Cas9 resulted in low seed
vigor under various conditions, which might be associated with the reduction
of amino acids in germinating seeds. Eleven amino acids involved in stress
tolerance, gibberellic acid synthesis and tricarboxylic acid cycle were
significantly reduced in osipms1 mutants compared to wildtypes during seed
A total of 1,209 differentially expressed genes (DEGs) were found in the
osipms1a mutant, most of which were involved in glycolysis, protein
processing, pyruvate, carbon, fructose and mannose metabolism. Further
analysis confirmed that the role of OsIPMS1 in seed vigor is involved in
starch hydrolysis, glycolytic activity and energy levels in germinating
This study provides insights into the function of OsIPMS1 on seed vigor and
should have practical applications in the improvement of rice.