Molecular Mechanism Of GmLIM1 Gene Regulation Of Soybean Plant Height

Plant height is one of important agronomic traits which affectes productivity in soybean,and it's meanful to eluciate its genetic basis and molecular regulation.In this study,two genes,GmLIM1a?Glycine max Long Internode Mutant 1a?and GmLIM1b,involved in regulation of soybean height,were cloned and characterized in detail.In addition,the two genes also provide an important point to relize the domestication process of soybean height.This research was meaningful for soybean height improvement breeding.In this study,a mutant with higher stem and longer internode,Gmlim1,was screened from EMS induced M2 population of our lab,which was 89%significantly higher than Williams 82.To clone the gene controlling the longer internode of Gmlim1,an F₂ segregating population was obtained.And then Gmlim1 locus was pinpoint to chr13:35,500,000-40,300,000 using BSA analysis method.Sequence analysis in the candidate region shows a 98,430 bp deletion containing 8 genes in the Gmlim1.The transgenic complementation experiment showes that either expressing Glyma.13G287600 or Glyma.13G288000 in Gmlim1 can recover the phenotype of the Gmlim1 mutant,while the plants knocking out Glyma.13G287600 or Glyma.13G288000 showed similar phenotype of Dongnong 50.Therefore,all the results proved that the loss function of Glyma.13G287600 and Glyma.13G288000 lead to the longer internode length of Gmlim1.Evolution and phylogenetic analysis indicate that Glyma.13G287600 and Glyma.13G288000 encode gibberellin?oxidases,which contains 3 sub gene family including a total of 27 genes in soybean genome?Glycine max Wm82.a2.v1?.Among these genes,only three genes,Glyma.11G003200,Glyma.13G287600 and Glyma.13G288000,were highly expressed,while,only Glyma.13G287600 and Glyma.13G288000 were expressed in V4 and V7 stage.Gibberelline?oxidases was an important enzyme which regulates gibberellin metabolism.Therefore,the endorgenious gibberellines were measured and the result showed that Gmlim1 had higher GA4 and lower GA34 comparing with Williams 82.It indicated that higher content of active gibberelline,GA4,in Gmlim1 leads to the longer internode phenotype,and also implied that GmLIM1a and GmLIM1b may catalyze the transformation of GA4 to GA34.The GWAS result showes that a CNV maker locate in the chromosome 13 which containes 5 genes?Glycine max W82.a2.v1?including GmLIM1a,GmLIM1b and three MYB genes,was significantly related to internode length,and named CNV-GmLIM1.The whole sequence of the CNV-GmLIM1 in the genome of Williams 82 and Zhonghuang 13 located on chr13:38,791,008-38,865,173 bp?74,165 bp?and chr13:38,670,241-39,744,516 bp?74,275 bp?,respectively.The CNV-GmLIM1 on the genome of Williams 82 and Zhonghuang 13 have 4 and 9-12 copies,respectively.In additional,60 out of 62 wild soybeans?Glycine soja?have one copy of CNV-GmLIM1,while only 12 out of 180 cultivated soybeans?Glycine max?have one copy.The analysis result of FST,?,and XP-CLR showed that CNV-GmLIM1 located in a selective sweep region.Extended haplotype homozygosity of an SNP site?EHHS?analysis also shows that CNV-GmLIM1 might be a domestication-related gene.Further analysis shows that the expression level of GmLIM1b was positively correlated with the copy number of CNV-GmLIM1and negatively correlated with internode length.These observations indicated that artificial selection of soybean height led to the selection on CNV-GmLIM1.