Mu Qi, Wei Jialu, Longest Hallie K, Liu Hua, Char Si Nian, Hinrichsen Jacob T, Tibbs-Cortes Laura E, Schoenbaum Gregory R, Yang Bing, Li Xianran, Yu Jianming
Department of Agronomy, Iowa State University, Ames, 50011, Iowa, USA.
Department of Plant and Soil Sciences, University of Delaware, Newark, 19716, Delaware, USA.
Plant J. 2024 Dec;120(5):2172-2192. doi: 10.1111/tpj.17111. Epub 2024 Nov 1.
Manipulating plant height is an essential component of crop improvement. Plant height was generally reduced through breeding in wheat, rice, and sorghum to resist lodging and increase grain yield but kept high for bioenergy crops. Here, we positionally cloned a plant height quantitative trait locus (QTL) qHT7.1 as a MYB transcription factor controlling internode elongation, cell proliferation, and cell morphology in sorghum. A 740 bp transposable element insertion in the intronic region caused a partial mis-splicing event, generating a novel transcript that included an additional exon and a premature stop codon, leading to short plant height. The dominant allele had an overall higher expression than the recessive allele across development and internode position, while both alleles' expressions peaked at 46 days after planting and progressively decreased from the top to lower internodes. The orthologue of qHT7.1 was identified to underlie the brachytic1 (br1) locus in maize. A large insertion in exon 3 and a 160 bp insertion at the promoter region were identified in the br1 mutant, while an 18 bp promoter insertion was found to be associated with reduced plant height in a natural recessive allele. CRISPR/Cas9-induced gene knockout of br1 in two maize inbred lines showed significant plant height reduction. These findings revealed functional connections across natural, mutant, and edited alleles of this MYB transcription factor in sorghum and maize. This enriched our understanding of plant height regulation and enhanced our toolbox for fine-tuning plant height for crop improvement.
调控株高是作物改良的一个重要组成部分。在小麦、水稻和高粱中，通常通过育种降低株高以抗倒伏并提高籽粒产量，但生物能源作物的株高则保持较高水平。在此，我们通过定位克隆了一个株高数量性状位点（QTL）qHT7.1，它是一个控制高粱节间伸长、细胞增殖和细胞形态的MYB转录因子。内含子区域740 bp的转座子插入导致了部分剪接异常事件，产生了一个包含额外外显子和提前终止密码子的新转录本，导致植株矮小。在整个发育过程和节间位置，显性等位基因的表达总体上高于隐性等位基因，而两个等位基因的表达均在种植后46天达到峰值，并从最上部节间到下部节间逐渐降低。已确定qHT7.1的直系同源基因是玉米短节间1（br1）位点的基础。在br1突变体中，外显子3有一个大的插入，启动子区域有一个160 bp的插入，而在一个天然隐性等位基因中发现一个18 bp的启动子插入与株高降低有关。在两个玉米自交系中，利用CRISPR/Cas9诱导br1基因敲除导致株高显著降低。这些发现揭示了高粱和玉米中该MYB转录因子的天然、突变和编辑等位基因之间的功能联系。这丰富了我们对株高调控的理解，并增强了我们用于作物改良微调株高的工具库。
