Cloning And Functional Verification Of IsGAI And IsGID1a Genes Related To Plant Height In Iris Sanguinea

Iris,a perennial herb in the Iridaceae family,is widely loved by people for its gorgeous color and unique flower pattern,and is widely used in landscaping.As one of the most obvious phenotypes of ornamental plants,plant height is sometimes changed to enhance plant ornamental and application value,so Iris plant height breeding has also attracted wide attention.With the development of genetic engineering breeding technology,the mining and analysis of genes related to plant height regulation can promote the practice of plant height breeding in genetic engineering.Gibberellin（GA）is known to be one of the main plant hormones affecting plant height,and several genes related to GA have been confirmed to affect plant height of a variety of plants.In this study,Iris sanguinea was selected as the experimental material,and GA promoted the plant height growth of I.sanguinea,and GA synthesis inhibitors（PAC）inhibited the plant height growth of I.sanguinea.Two genes related to gibberellin signal transduction,IsGAI and IsGID1a,were selected from the transcriptomes of I.sanguinea,and were cloned and bioinformatics analyzed.Allogeneic transformation of Arabidopsis thaliana showed that both of these genes regulated plant height.The results laid a foundation for the study of plant height regulation mechanism and plant height breeding by genetic engineering.The specific research results are as follows:（1）The 4-leaf seedlings of I.sanguinea were treated with exogenous GA and PAC at different concentrations for 4 consecutive times,concentrations of GA and PAC,the plant height of 50 mg/L,100 mg/L and 200 mg/L GA increased by 5.7%,8.8%and 12.7%,respectively,compared with the control group.Exogenous PAC treated with 50 mg/L,100mg/L and 200 mg/L reduced the plant height of I.sanguinea by 19.3%,21%and 22.2%compared with the control.（2）Two genes,IsGAI and IsGID1a,were cloned using I.sanguinea cDNA as template.Bioinformatics analysis showed that IsGAI gene encoded 529 amino acids,the molecular weight of the protein was 57.66 k Da,the theoretical isoelectric point was 5.08.The IsGID1a gene encoded 343 amino acids,the molecular weight of the protein was 38.28 k Da,and the theoretical isoelectric point was 6.46.IsGAI and IsGID1a proteins are both unstable hydrophilic proteins without transmembrane structure and signal peptide,with 4 and 2glycosylation sites,respectively,and both are mainly phosphorylated by serine.It is predicted that IsGAI protein and IsGID1a protein may participate in plant growth and development by directly participating in GA signal transduction.（3）Construct plant overexpression vectors of pCAMBIA1300-IsGAI-GFP and pCAMBIA1300-IsGID1a-GFP,transform Agrobacterium GV3101,transform A.thaliana,and obtain transgenic A.thaliana T₃ strain.Phenotypic observation confirmed that IsGAI gene allogeneic overexpression in A.thaliana inhibited plant height growth,hypocotyl elongation and scapes.Heterologous overexpression of IsGID1a gene in A.thaliana can promote plant height growth,hypocotyl elongation and scapes.（4）GA（100μm/L,34.64 mg/L）was applied to A.thaliana with IsGAI and IsGID1a genes.It was found that exogenous GA could remove the dwarfing effect of IsGAI gene on A.thaliana to a certain extent,and the plant height of A.thaliana with IsGID1a gene was also increased.