Fig. 8.

Schematic model for the role of LGS1 in the regulation of grain length, grain width, and grain weight. LGS1 forms a protein complex with OsGIF to regulate gene expression. The transcript level of LGS1 is regulated by miR396. LGS1 promotes cell division, cell extension, and cell expansion, resulting in increases in vegetative biomass and spikelet glume volume. During grain development, LGS1 enhances the grain filling rate and increases grain length and endosperm cell numbers, leading to the production of enlarged grains and higher yield in rice. Furthermore, the expression of miR396 is up-regulated by stress, which in turn reduces the transcript level of lgs1. The nucleotide substitution in LGS1 prevents regulation of LGS1 by miR396 and allows the LGS1 transcript to accumulate during adversity stress, which improves stress tolerance in rice seedlings.