A Gain-of-Function Mutant of IAA7 Inhibits Stem Elongation by Transcriptional Repression of EXPA5 Genes in Brassica napus

Abstract

Plant height is one of the most important agronomic traits of rapeseeds. In this study, we characterized a dwarf Brassica napus mutant, named ndf-2, obtained from fast neutrons and DES mutagenesis. Based on BSA-Seq and genetic properties, we identified causal mutations with a time-saving approach. The ndf-2 mutation was identified on chromosome A03 and can result in an amino acid substitution in the conserved degron motif (GWPPV to EWPPV) of the Auxin/indole-3-acetic acid protein 7 (BnaA03.IAA7) encoded by the causative gene. Aux/IAA protein is one of the core components of the auxin signaling pathway, which regulates many growth and development processes. However, the molecular mechanism of auxin signal regulating plant height is still not well understood. In the following work, we identified that BnaARF6 and BnaARF8 as interactors of BnaA03.IAA7 and BnaEXPA5 as a target of BnaARF6 and BnaARF8. The three genes BnaA03.IAA7, BnaARF6/8 and BnaEXPA5 were highly expressed in stem, suggesting that these genes were involved in stem development. The overexpression of BnaEXPA5 results in larger rosettes leaves and longer inflorescence stems in Arabidopsis thaliana. Our results indicate that BnaA03.IAA7- and BnaARF6/8-dependent auxin signal control stem elongation and plant height by regulating the transcription of BnaEXPA5 gene, which is one of the targets of this signal.

Genome-Wide Analysis of AP2/ERF Gene Superfamily in Ramie (Boehmeria nivea L.) Revealed Their Synergistic Roles in Regulating Abiotic Stress Resistance and Ramet Development

“…We used STRING software to map an integrated protein interaction network based on AtERF11 and AtERF4. The results ( Figure 11 ) show that they first formed a complex through their EAR-motif and TPL protein, which in turn bind to genes related to WUS [ 54 ] and the growth hormone pathway [ 55 , 56 , 57 , 58 ] to regulate tillering and branching in plants. These results reinforce the potential role of BnERF-30 and BnERF-32 in the ramet traits of ramie.…”

Analysis of the Candidate Genes and Underlying Molecular Mechanism of P198, an RNAi-Related Dwarf and Sterile Line

“…For example, a mutation in the IAA2 gene of B. napus results in semidwarfism and curly leaves [ 95 ]. Mutations in the IAA7 genes of B. napus affect stem elongation, reproduction, and plant height [ 96 , 97 ]. In this study, eight IAA2 genes, three IAA3 genes, three IAA7 genes, one IAA8 gene, two IAA9 genes, one IAA12 gene, two IAA13 genes, one IAA16 gene, three IAA17 genes, one IAA19 gene, one IAA28 gene, and three IAA29 genes were significantly downregulated in P198.…”

Brassica napus Haploid and Double Haploid Production and Its Latest Applications

“…Zhao et al [125] and Wei et al [126] provided new insights regarding the molecular mechanisms underlying dwarfism of B. napus. Using the "Aiyuan1" DH lines and "Zhongyou 821" cultivar, a new dwarf locus-DS-4 encoding nucleus-targeted auxin/indole-3-acetic acid (Aux/IAA) protein-was identified.…”