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The gene Oryza sativa indoleacetic acid 13(OsIAA13) is involved in auxin signaling and controls the expression of genes that are required for lateral root initiation in rice1. The open reading frame (ORF) length of OsIAA13 was 2116 bp. It's located on the long arm of chromosome 3.
A rice gain-of-function mutant, Osiaa13, contains a single amino acid substitution (G to A, which resulted in a single amino acid substitution, glycine (G) to serine (S), in the core sequence in domain II of OsIAA13) in the core sequence required for the degradation of the OsIAA13 protein. The Osiaa13 mutant displayed typical auxin-related phenotypes: the number of lateral roots was significantly reduced and the root gravitropic response was defective. Osiaa13 mutants also exhibited altered GUS staining controlled by the DR5 promoter in lateral root initiation sites. Furthermore, expression levels of several genes that might be associated with lateral root initiation were altered in Osiaa13. OsIAA13 encodes a member of the rice Aux/IAA protein family and is believed to play an essential part in blocking auxin signaling by repressing ARF function as a transcriptional regulator. The gain-of-function mutant OsIAA13 shares high sequence similarity with OsIAA11 and OsIAA30 in rice, and with AXR2/IAA7, SLR/IAA14, IAA16, and AXR3/IAA17 in Arabidopsis2. Osiaa11 showed a similar phenotype to Osiaa13: the lateral root number of Osiaa11 was reduced because of a defect in LRP initiation but the crown root number was not reduced. Examination of the RiceXPro database revealed that OsIAA13, OsIAA11, and OsIAA30 show similar gene expression patterns indicating that the function of OsIAA30 might be redundant with OsIAA13 and OsIAA11 in lateral root initiation. OsIAA13, OsIAA11, and OsIAA30 may play an important role in lateral root formation but not in crown root formation.
1.Yuka Kitomi;Hiroki Inahashi;Hinako Takehisa;Yutaka Sato;Yoshiaki Inukai, OsIAA13-mediated auxin signaling is involved in lateral root initiation in rice, Plant Science, 2012, 190: 116-122 2.M. Jain, N. Kaur, R. Garg, J.K. Thakur, A.K. Tyagi, J.P. Khurana, Structure expression analysis of early auxin-responsive Aux/IAA gene family in rice (Oryza sativa), Functional and Integrative Genomics 6 (2006) 47–59.
