ALI-1, candidate gene of B1 locus, is associated with awn length and grain weight in common wheat

Abstract

Awn plays a vital role in the photosynthesis, grain production and drought tolerance of common wheat; however, works on the systematic identification or cloning of genes controlling wheat awn length (AL) were seldom reported. Here, we conducted the Genome-wide association study (GWAS) in 364 wheat accessions and identified 25 loci involved in the AL, including dominant awn suppressors B1, B2 and four homologs of awn controlling genes in rice and barley. Furthermore, the B1 locus was mapped to a 125-kb physical interval harboring two genes on chromosome 5AL through map-based cloning. As the candidate gene for B1 locus, a C2H2 zinc finger gene Awn Length Inhibitor 1 (ALI-1) expressed predominantly in the developing spike of awnless individuals and suppresses downstream genes transcriptionally. ALI-1 reduces cytokinin content and simultaneously restrains cytokinin signal transduction, which leads to a stagnation of cell proliferation and reduction of cell number in awn. Noteworthily, ali-1 was the first awn controlling locus that observed increasing grain length in wheat, which is a valuable supplemental attribution of awn on grain weight besides photosynthesis. Thus, ALI-1 pleiotropically regulates awn and grain development, and this work provides a strategy to achieve improved grain yield and address future extreme climate.\n\nHighlightALI-1, candidate gene of awn suppressing B1 locus, associates with awn length and grain length, providing a reacquaint of the effect of wheat awn on grain production.