Reducing brassinosteroid signalling enhances grain yield in semi-dwarf wheat
Long Song, Jie Liu, Beilu Cao, Bin Liu, Xiao–Ping Zhang, Zhaoyan Chen, Chaoqun Dong, Xiangqing Liu, Zhaoheng Zhang, Wenxi Wang, Lingling Chai, Jing Liu, Jun Zhu, Shubin Cui, Fei He, Huiru Peng, Zhaorong Hu, Zhenqi Su, Weilong Guo, Mingming Xin, Yingyin Yao, Yong Yan, Song YinMing, Guihua Bai, Qixin Sun, Zhongfu Ni
Abstract
Abstract Modern green revolution varieties of wheat ( Triticum aestivum L.) confer semi-dwarf and lodging-resistant plant architecture owing to the Reduced height-B1b ( Rht-B1b ) and Rht-D1b alleles 1 . However, both Rht-B1b and Rht-D1b are gain-of-function mutant alleles encoding gibberellin signalling repressors that stably repress plant growth and negatively affect nitrogen-use efficiency and grain filling 2–5 . Therefore, the green revolution varieties of wheat harbouring Rht-B1b or Rht-D1b usually produce smaller grain and require higher nitrogen fertilizer inputs to maintain their grain yields. Here we describe a strategy to design semi-dwarf wheat varieties without the need for Rht-B1b or Rht-D1b alleles. We discovered that absence of Rht-B1 and ZnF-B (encoding a RING-type E3 ligase) through a natural deletion of a haploblock of about 500 kilobases shaped semi-dwarf plants with more compact plant architecture and substantially improved grain yield (up to 15.2%) in field trials. Further genetic analysis confirmed that the deletion of ZnF-B induced the semi-dwarf trait in the absence of the Rht-B1b and Rht-D1b alleles through attenuating brassinosteroid (BR) perception. ZnF acts as a BR signalling activator to facilitate proteasomal destruction of the BR signalling repressor BRI1 kinase inhibitor 1 (TaBKI1), and loss of ZnF stabilizes TaBKI1 to block BR signalling transduction. Our findings not only identified a pivotal BR signalling modulator but also provided a creative strategy to design high-yield semi-dwarf wheat varieties by manipulating the BR signal pathway to sustain wheat production.