Identification And Phenotype Characterization Of Ckrc Mutants In Arabidopsis Thaliana

Auxin plays an important role in plant growth and development,including elongation,division and differentiation of cells,growth of roots and leaves,differentiation of vascular tissue,dominance and photoisomerization of plant.There are multiple pathways for auxin biosynthesis and metabolism,forming a complex web,for which we are still far from forming a clear picture.Based on our previous works on ckrc1-1(CKRC1 encodes tryptophan aminotransferase(TAA1)for IAA biothynthesis),the aim of this study to isolate more Arabidopsis ckrc mutants that are likely to have low auxin(IAA)levels in roots,on which further molecular genetic and biochemical studies should uncover important genes in controlling auxin biosynthesis and metabolism.257,500 seeds were screened and there are 209 seedlings with curling root phenotype when grown in MS medium containing 0.1?M t Z.10 of those lines showed root curling in the second screening.Biochemical complementation experiment showed that there are two pin-like mutants t1 and t2,four aux-like mutants t5,t6,t7 and t8,four wei2/wei7-like mutants t3,t4,t9 and t10 in the 10 mutants.Studies on another mutant zb11 showed that this mutant had the phenotype of auxin deficient such as its relative short primary root and weak gravitropism in its roots,which can be rescued by exogenous Indole-3-acetic acid(IAA).Moreover,the root curling phenotype of zb11 could be complemented by low concentrations of IAA,NAA or 2,4-D.GC-MS results confirmed that the endogenous IAA level in zb11 mutant was significantly reduced,indicating that zb11 is an auxin deficient mutant.