Creating of novel Wx allelic variations significantly altering Wx expression and rice eating and cooking quality.

Granule-bound starch synthase I (GBSSI) encoding gene Waxy (Wx), which largely regulates the amylose content of rice grains, is a master module determining rice eating and cooking quality (ECQ). Fine-tuning amylose level of grains is an ideal strategy to improve rice quality. Through fine editing of Wx promoter and 5'UTR by CRISPR/Cas9 system, we created 14 types of novel Wx allelic variations, of which MT7 and MT13 were able to alter Wx expression and amylose content of grains.

A point mutation in the rice alpha-tubulin gene OsTUBA3 causes grain notching.

Grain notching is a common deformation that decreases rice (Oryza sativa) quality; however, the underlying molecular basis causing grain notching remains unclear. We report mechanisms underlying grain notching in Small and notched grain (Sng) mutants, which contained an arginine to histidine substitution at amino acid position 422 (R422H) of the α-tubulin protein OsTUBA3. The R422H mutation decreased cell length and increased cell width/height of glumes and caryopses, but led to elongated caryopses compressed within shortened glumes, thus giving rise to notched and small grains.

Waxy is an important factor for grain fissure resistance and head rice yield as revealed by a genome-wide association study.

Head rice yield (HRY) is an essential quality trait, and is sensitive to environmental stresses during the grain-filling, harvest, and postharvest stages. It is therefore important for rice production and global food security to select for superior HRY traits; however, the molecular basis of this trait remains unknown. Using diverse rice germplasm material, we performed a genome-wide association study of grain fissure resistance (GFR), the phenotype most associated with HRY, and found that the granule-bound starch synthase I gene Waxy is an important gene controlling GFR.