CRISPR/Cas9 mutagenesis generated elite alleles of a novel yield gene An-1 leading to increased grain number in rice (Oryza sativa L.)

Domestication of rice (Oryza sativa L.) dates back to 8000 years ago when selection for yield traits began through artificial selection. Projected demand in rice production, yield plateau and changing climate gives us a clue that enhancing yield potential is vital for food security. Identifying genes controlling yield traits and mechanisms like C₄ photosynthesis is warranted to achieve sustained increase in rice production. In this study, efforts were made to exploit a novel domestication gene An-1 for enhancing yield potential in rice through creation of targeted mutations using CRISPR/Cas9 mutagenesis. Evaluation of 312 T₀ progenies of a rice cultivar ASD 16 identified 17 multi-allelic, seven bi-allelic and four mono-allelic mutations. Evaluation of T₂ and T₃ progenies identified homozygous and transgene free mutants possessing increased number of grains per panicle. Evaluation of T₄ progenies revealed that the mutant progenies were found to possess increased secondary branches in the panicle (22.8 %), increased number of spikelets per panicle (34.8 %) and increased single plant yield (35.25 %) when compared to the wild type ASD 16. This study has identified An-1 as a novel candidate gene for yield enhancement in rice.