Identification And Mapping Of Early Flowering Soybean Mutants Derived From Huaxia 3

South China is one of the main areas for soybean production because it located in the tropical and subtropical zone with abundant heat and water resources,while it is main region for soybean processing and consumption.However,because soybean is sensitive to short photoperiods,early flowering and maturation limit the soybeans yields in low latitude regions.It is important to study the molecualr mechanisms of response to photoperiod-temperature in soybeans.In this study,two early flowering mutants were selected from the mutant library derived from Huaxia 3?J gene function-lost type?.The photoperiod-temperatural characters of those mutants were identified by different planting and climate chambers.The genome difference were compared between mutants and wild-type by whole genome sequencing.The candidate genes were tryed to identify by BSA-MutMap between mutants and Huaxia3.The main results are as follows:1.The investigation of the flowering times soybean mutants in the field during whole–year sowing and in climate chanbers under combining photoperiods and temperature.M3-283 and EMS-23-8 were early flowering mutants through EMS and ⁶⁰Co.The first flowering time of the two mutants were always earlier than that of the wild-type Huaxia 3at any sowing season.The flowering times of M3-283 are earlier than that of wild-type Huaxia 3 in spring,while the flowering times of M3-283 are more earlier than that in summer.The flowering times of EMS-23-8 are relatively stable in spring and summer,and the flowering time is obviously delayed in the long-photoperiods conditions.Through the combination of photoperiods and temperature in climate chambers,we found that the flowering time is coordinatedly regulated by photoperiod and temperature in soybean The EMS-23-8 has the lowest sensitivity to photoperiod and temperature.The flowering tim of M3-283 is sensitive to the photoperiod and temperature.Wild-type Huaxia3 is more sensitive to the photoperiod and temperature.2.The genome analysis of M3-283 and EMS-23-8 by whole-genome resequencing.Compared to wild-type Huaxia 3,mutant M3-283 had 39874 Single NucleotidePolymorphisms?SNPs?,4050 insertion/deletion?InDel?,while mutant EMS-23-8 had 66276SNPs,8842 InDel.The distribution of SNP and InDel had the tendency of specific chromosome.The SNPs were enriched on chromosome 13 for M3-283 and EMS-23-8,and the fewer SNPs distributed on chromosome 14 for M3-283 and chromosome 19 for EMS-23-8.The InDels were enriched on chromosome 13 for M3-283 and EMS-23-8,and the fewer InDels distributed on chromosome 4,5,and 14 with only one InDel for M3-283and chromosome 19 with only 9 for EMS-23-8.3.The genome analysis of genes related to flowering.Compared with soybean gene database,five mutation genes from 524 mutation genes in M3-283,Glyma.08G039800,Glyma.08G209600,Glyma.13G062500,Glyma.16G027200andGlyma.20G025900invovled in soybean flowering.Compared with soybean genes database,8 mutation genes from 1161 mutation genes in EMS-23-8,Glyma.03G211500,Glyma.05G122400,Glyma.10G209600,Glyma.13G050300,Glyma.13G062500,Glyma.14G049700,Glyma.15G166600 and Glyma.16G027200 invovloed in soybean flowering.These informations provided some direction for subsequent study works.4.The early-flowering trait of M3-283 was caused by a single gene recessive mutation.The flowering time of F₂ populations with 68 individuals,derived from the cross of M3-283and Huaxia 3,were investagted during summer.There were 55 individuals in the later flowering group and 13 early individuals in the early flowering group,and the proportions were chi-squared in accordance with 3:1.Among the F_2:3:3 derived lines,there was not segregated for 6 lines from early flowering individuals,but 10 lins were segregated and 19lines were not segregated derived from later flowering individuals.The ration is nearly 3:1when the F_2:3:3 segregating populations were grouped according to the flowering time of the wild-type and mutants,in which 35 individuals were early flowering and 88 individuals were late flowering in total 123 individuals from the 10 segregated F_2:3:3 lines.Genetic analysis showed that M3-283 early flowering mutants were single gene recessive mutants.5.Gene mappin of mutant gene in M3-283.The F₂ segregating populations of M3-283and Huaxia 3 were grouped according to the first flowering time.The mutant gene of the early flowering mutant M3-283,was located 1370508bp-3607319bp?2.13MB?or25626353bp-26808936bp?1.12Mb?on chromosome 16 by the BSA-MutMap.The linkage analysises were conducted in F₂ and F_2:3:3 segregating populations using molecular markers from genome resequencing date.The result indicated the mutant gene located in region of1370508bp-3607319bp.Combining with the high-throughput sequencing informations of Huaxia 3 and mutant M3-283,Glyma.16G027200 may be the causal genes for eraly flowering.This gene is a homologous gene of Arabidopsis thaliana SPA1?SUPPRESSOR of phyA-105?,and there are three mutations occurring in this gene.Glyma.16G027200?SPA1 homologue in soybean?may act directly or indirectly on the flowering-related genes E3 and E4?PhyA homologous genes in soybean?to inhibit soybean flowering and regulate biological clock rhythms.