Abstract

Spikelet number per panicle is a determinative factor of rice yield. DNA repair epigenetically alters the DNA accessibility, which can eventually regulate the transcription of the target genes. However, what and how DNA repair genes are related to rice spikelet development remains unknown. Here, we report the map-based cloning of a novel spikelet number geneDES4encoding a tetratricopeptide domain-containing protein. DES4 is a close ortholog ofArabidopsisBRU1, which is functionally related to axillary meristem development. A single base pair deletion in the last exon ofDES4caused a premature stop of the resulting protein. Thedes4mutant exhibited dwarf, reduced tiller, and spikelet numbers phenotypes, as well as hypersensitivity to genotoxic stresses, suggesting its essential role in DNA repair.DES4is predominantly expressed in young panicles and axillary meristems, and DES4 protein is localized in nucleus. A set of DNA repair genes such ascyclins,KUs(KD subunits) andrecombinaseswere differentially regulated indes4. Meanwhile, rice spikelet number genesLAX1,LAX2, andMOC1were significantly down-regulated indes4. In morphology,des4showed more severe reduction of spikelet numbers thanlax1,lax2, andmoc1, suggesting thatDES4may work upstream of the three genes.Keywords:rice (Oryza sativaL.);DNA repair;spikelet number;tetratricopeptide;LRR (leucine-rich repeat)