Expression of BpIAA10 from Betula platyphylla (birch) is differentially regulated by different hormones and light intensities

Abstract

The Auxin/Indole acetic acid (Aux/IAA) genes are auxin primary response genes that play a pivotal role in apical dominance, phototropism, and embryonic development. In this study, we cloned the promoter of BpIAA10 and constructed a BpProIAA::Luc vector for transformation into Arabidopsis thaliana. The results indicated that BpIAA10 is expressed in the apical meristem, embryonic leaves, and young stem. The tissue-specific expression pattern was same in A. thaliana and Betula platyphylla. Additionally, IAA, IBA, GA, SA, and ABA could induce the expression of BpIAA10 while MeJA inhibited the expression of BpIAA10, suggesting that plant hormones influence the expression of BpIAA10. Strong light conditions also markedly induced the expression of BpIAA10, indicating that BpIAA10 is sensitive to light intensity and that light may be sufficient but not necessary for the normal expression of BpIAA10. Conversely, IBA-induced expression of BpIAA10 was suppressed with strong light, suggesting that IBA-induced BpIAA10 expression is partly light dependent. We predicted the presence of cis-acting elements in the BpIAA10 promoter and found many different types cis-acting elements. Furthermore, promoter analysis and yeast one-hybrid assay revealed that the bait2 (TGA-element) can specifically bind to transcription factors 14-3-3 and Ribosomal_L2, and the bait3 (ntBBF1ARROLB) can specifically bind to FAR1, 14-3-3 Like and kinesin-like protein. Therefore, our study characterized the expression of BpIAA10 and found five transcription factors that regulate expression of BpIAA10. This provides a basis for determining the function of BpIAA10.