OsPK2 Gene Involved in Starch Synthesis and Grain Filling in Rice

Starch is the main form of energy storage in higher plants. While a big part of starch biosynthesis has been defined, the complete mechanism remains unknown. To further study this pathway, the team of Yicong Cai from the China National Rice Research Institute identified a defective grain filling rice mutant, ospk2, which displays lower grain weight, decreased starch content and alteration of starch properties compared to wildtypes.

The normal starch compound granules were greatly reduced and more single granules filled the endosperm cells of the ospk2 mutant. The team also found that the germination rate of ospk2 mutant seeds after one-year storage was significantly reduced compared to wildtypes. Moreover, the mutation also leads to multiple metabolic disorders in ospk2 mutants.

Analysis of the OsPK2 gene indicated that it encodes a pyruvate kinase, which initiates an irreversible step of glycolysis. OsPK2's protein is situated in chloroplasts.

These results provide clues into the role of OsPK2 in plant seed development, especially in starch synthesis and grain filling. The gene could be useful in genetic improvement of high yield and rice grain quality.

For more information, read the article in Plant Biotechnology Journal.