Identification of a novel gain-of-function mutant allele,slr1-d5,of rice DELLA protein

Controling the height of crops plays a crucial role for their yields. The large scale utilization of semi-dwarf varieties has greatly improved crop yield, providing an effective support for world food security. In rice, a main food for over half of the world’s population, a number of dwarf loci have been identiifed. However, most of them are recessive, such as the ‘green revolution’ genesd1. To gain more beneifcial loci for rice breeding programs, exploring new mutations is needed, especialy the dominant loci which can be used broadly for hybrid breeding. Here, we isolated a novel dominant dwarf rice mutant, slr1-d5. Al of the internodes ofslr1-d5are reduced. We ifnd that the responsiveness ofslr1-d5to gibberelin （GA）, GA3, was signiifcantly reduced. Map-based cloning revealed that the dominant dwarifsm ofslr1-d5was caused by an amino acid substitution in the N-terminal TVHYNP domain of rice DELLA protein, SLR1, where the conserved amino acid Pro （P） was substituted to His （H）. Our ifndings not only further prove the pivotal role of TVHYNP motif in regulating SLR1 stability, but also provide a new dwarf source for improvement of rice germplasms.