Summary Grain length is one of the most important factors in determining wheat yield. Here, a stable QTL for grain length was mapped on chromosome 1B in a F10 recombinant inbred lines (RIL) population, and the gene TaGL1‐B1 encoding carotenoid isomerase was identified in a secondary large population through multiple strategies. The genome‐wide association study (GWAS) in 243 wheat accessions revealed that the marker for TaGL1‐B1 was the most significant among all chromosomes. EMS mutants of TaGL1 possessed significantly reduced grain length, whereas TaGL1‐B1‐overexpressed lines possessed significantly increased grain length. Moreover, TaGL1‐B1 strongly interacted with TaPAP6. TaPAP6‐overexpressed lines had significantly increased grain length. Transcriptome analysis suggested that TaPAP6 was possibly involved in the accumulation of JA (jasmonic acid). Consistently, JA content was significantly increased in the TaGL1‐B1 and TaPAP6 overexpression lines. Additionally, the role of TaGL1‐B1 in regulating carotenoids was verified through QTL mapping, GWAS, EMS mutants and overexpression lines. Notably, overexpression of TaGL1‐B1 significantly increased wheat yield in multiple locations. Taken together, overexpression of TaGL1‐B1 enhanced grain length, probably through interaction with TaPAP6 to cause the accumulation of JA that improved carotenoid content and photosynthesis, thereby resulted in increased wheat yield. This study provided valuable genes controlling grain length to improve yield and a potential insight into the molecular mechanism of modulating JA‐mediated grain size in wheat.

Common wheat provides approximately 20% of the total dietary calorie intake of human beings. Recent technological advances in whole‐genome sequencing and their application in wheat and its progenitor species provide new opportunities to uncover the genetic variation of wheat traits and to accelerate the traditional breeding (TB) strategies in the context of genomics‐assisted breeding (GAB). Integration of TB, marker‐assisted selection (MAS) and genomic selection (GS) with high‐density SNP markers is expected to accelerate the breeding process and to further enhance genetic gain. With the assistance of the next‐ or third‐generation sequencing technologies and high‐throughput phenotyping platforms, GAB can now realistically be considered in the following area: (i) genome sequencing and high‐quality assembly to uncover new variations, (ii) whole‐genome sequence‐based association studies, (iii) gene function (or functional gene) identification and (iv) integration of whole genomic breeding information, utilizing multi‐omics data and different breeding strategies. We argue that GAB is becoming the preferred strategy in pursuit of new wheat cultivars with superior traits on high yielding, high nutritional quality, climate‐resilience and so on.

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Fusarium crown rot (FCR) and sharp eyespot (SE) are serious soil‐borne diseases in wheat and its relatives that have been reported to cause wheat yield losses in many areas. In this study, the expression of a cell wall invertase gene, TaCWI‐B1, was identified to be associated with FCR resistance through a combination of bulk segregant RNA sequencing and genome resequencing in a recombinant inbred line population. Two bi‐parental populations were developed to further verify TaCWI‐B1 association with FCR resistance. Overexpression lines and ethyl methanesulfonate (EMS) mutants revealed TaCWI‐B1 positively regulating FCR resistance. Determination of cell wall thickness and components showed that the TaCWI‐B1‐overexpression lines exhibited considerably increased thickness and pectin and cellulose contents. Furthermore, we found that TaCWI‐B1 directly interacted with an alpha‐galactosidase (TaGAL). EMS mutants showed that TaGAL negatively modulated FCR resistance. The expression of TaGAL is negatively correlated with TaCWI‐B1 levels, thus may reduce mannan degradation in the cell wall, consequently leading to thickening of the cell wall. Additionally, TaCWI‐B1‐overexpression lines and TaGAL mutants showed higher resistance to SE; however, TaCWI‐B1 mutants were more susceptible to SE than controls. This study provides insights into a FCR and SE resistance gene to combat soil‐borne diseases in common wheat.