Characterization Of A Panicle Development Mutant Simads34 In Foxtail Millet (Setaria Italica(L.)P.Beauv.) And Function Analysis Of Candidate Gene

Grain yield showed highly significant positive correlation with thousand seed weight,No.of seed per plant,plant architecture and panicle length as well as the panicle width had highly significant positive correlation with grain yield attributers,thousand seed weight and number of seed per plant.Panicle development and inflorescence architecture are the most important agronomical traits and closely associated with grain yield of foxtail millet(Setaria italica(L)P.Beauv.).Here,we isolated a panicle development mutant simads34 from a foxtail millet EMS mutant library.We reported that the simads34 mutant was significantly altered the inflorescence architecture and decreased grain yield.Investigation of agronomic traits increased panicle width by 16.8%,primary branch length by 10%,number of primary branches by 30.9%,reduced panicle length by 25.2%,and grain weight by 25.5%in simads34 compared with wild-type plants.MADS-box transcription factors participate in regulating various developmental processes in plants.Genetic analysis of a simads34×SSR41 F2 population indicated that the simads34 phenotype was controlled by a recessive gene.Map-based cloning and bulked-segregant analysis sequencing demonstrated that a single G-to-A transition in the fifth intron of SiMADS34 in the mutant led to an alternative splicing event and caused an early termination codon in this causal gene.SiMADS34 mRNA was expressed in all of the tissues tested,with high expression levels at the heading and panicle development stages.Subcellular localization analysis showed that SiMADS34 predominantly accumulated in the nucleus.Transcriptome sequencing identified 241 differentially expressed genes related to inflorescence development,cell expansion,cell division,meristem growth and peroxide stress in simads34.Notably,an SPL14-MADS34-RCN pathway was validated through both RNAseq and qPCR tests,indicating the putative molecular mechanisms regulating inflorescence development by SiMADS34.Our study identified a novel MADS-box member in foxtail millet,and provides a useful genetic resource for inflorescence architecture and grain yield research.