水稻短粒突变体sgl3的鉴定与基因定位OA

Grain size is one of the key agronomic traits that determine rice yield.Identification and characterization of novel grain size genes can provide valuable genetic resources for breeding high-yield and high-quality rice lines.In this study,a short grain mutant sgl3(short grain length 3)was obtained through ethyl methane sulfonate(EMS)mutagenesis.Microscopic observations via paraffin sectioning and scanning electron microscopy(SEM)revealed that the reduced grain length of sgl3 was mainly caused by shortened glume cells.Transcriptome sequencing(RNA-seq)and quantitative real-time PCR(qRT-PCR)results showed that the sgl3 mutation led to expression alterations of genes related to phytohormones,cell cycle,and cell expansion.Genetic analysis indicated that the sgl3 trait was controlled by a single recessive gene.Using a map-based cloning strategy,SGL3 was mapped to a 224 kb interval between molecular markers R4 and R5 on rice chromosome 3,which contains 25 open reading frames(ORFs).Resequencing and Sanger sequencing of PCR amplicons with specific primers confirmed that sgl3 harbored a single nucleotide substitution from A to G in the coding region of LOC_Os03g19980,resulting in an amino acid change from aspartic acid(Asp)to glycine(Gly).Quantitative real-time PCR(qRT-PCR)expression analysis showed that LOC_Os03g19980 was highly expressed in young panicles,while its expression level was significantly downregulated in the sgl3.These results demonstrate that LOC_Os03g19980 is the candidate gene for SGL3,which encodes a tetratricopeptide repeat(TPR)-like helical protein,and is a novel,previously unreported gene regulating rice grain size.The present findings lay a foundation for further enriching the molecular regulatory network of grain size in rice.