Down-regulation of BdBRI1, a putative brassinosteroid receptor gene produces a dwarf phenotype with enhanced drought tolerance in Brachypodium distachyon

作者：Feng Ying; Yin Yanhai^*; Fei Shuizhang

来源：Plant Science, 2015, 234: 163-173.

DOI：10.1016/j.plantsci.2015.02.015

• Brassinosteroids
• BRI1
• Brachypodium distachyon
• Drought tolerance
• RNAi
• Grass

Brassinosteroids (BRs) play important roles in plant growth, development and responses to a range of environmental cues. Although the mechanism of how BRs regulate growth and development is wellunderstood in Arabidopsis, the effect of BRs on stress tolerance, particularly drought tolerance remains unknown. We isolated a BRI1 (BRASSINOSTEROID INSENSITIVE I) homologous gene, BdBRI1 from Brachypodium distachyon, a model for temperate grasses and cereals, created and characterized RNA interference (RNAi) knockdown mutants for BdBRI1 in Brachypodium. The loss-of-function BdBRI1-RNAi mutants exhibited reduced plant height, shortened internodes, narrow and short leaf, and reduced expression of BR signaling genes, BdBES1, BdBZR1,BdBLE2, and enhanced expression of BR biosynthesis genes BdD2, BdCPD and BdDWF4. More importantly, BdBRI1 RNAi mutants exhibited enhanced drought tolerance, accompanied by highly elevated expression of drought-responsive genes, BdP5CS, BdCOR47/BdRD17, together with BdERD1 and BdRD26, two putative targets of the transcription factors BES1 and BZR1 that are key components of the BR signaling pathway. Our results suggest that BR signaling and biosynthesis are largely conserved among Arabidopsis, rice and Brachypodium, and that BR signaling plays an important role in drought tolerance by directly regulating expression of key drought-responsive genes. The effect of BR biosynthesis or crosstalks between BR and other hormones or components of stress signaling pathways on drought tolerance is discussed.

• 出版日期2015-5