Auxin signal transcription factor regulates expression of the brassinosteroid receptor gene in rice. (10th January 2013)

• Record Type: Journal Article
• Authors: Sakamoto, Tomoaki; Morinaka, Yoichi; Inukai, Yoshiaki; Kitano, Hidemi; Fujioka, Shozo
• Is Part Of: Plant journal. Volume 73:Number 4(2013:Feb.)
• Page Start: 676
• Page End: 688
• Publication Date: 2013-01-10
• Subjects: Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.12071
• Languages: English
• ISSNs: 0960-7412

Abstract

<abstract abstract-type="main" id="tpj12071-abs-0001"> <title>Summary</title> <p>The phytohormones auxins and brassinosteroids are both essential regulators of physiological and developmental processes, and it has been suggested that they act inter‐dependently and synergistically. In rice (<italic>Oryza sativa</italic>), auxin co‐application improves the brassinosteroid response in the rice lamina inclination bioassay. Here, we showed that auxins stimulate brassinosteroid perception by regulating the level of brassinosteroid receptor. Auxin treatment increased expression of the rice brassinosteroid receptor gene <italic>OsBRI1</italic>. The promoter of <italic>OsBRI1</italic> contains an auxin‐response element (AuxRE) that is targeted by auxin‐response factor (ARF) transcription factors. An AuxRE mutation abolished the induction of <italic>OsBRI1</italic> expression by auxins, and <italic>OsBRI1</italic> expression was down‐regulated in an <italic>arf</italic> mutant. The AuxRE motif in the <italic>OsBRI1</italic> promoter, and thus the transient up‐regulation of <italic>OsBRI1</italic> expression caused by treatment with indole‐3‐acetic acid, is essential for the indole‐3‐acetic acid‐induced increase in sensitivity to brassinosteroids. These findings demonstrate that some ARFs control the degree of brassinosteroid perception required for normal growth and development in rice. Although multi‐level interactions between auxins and brassinosteroids have previously been reported, our findings suggest a mechanism by which auxins control cellular sensitivity to brassinosteroids, and further support the notion that interactions between auxins and brassinosteroids are extensive and complex.</p> </abstract>