SummaryThe marriage of metabolomic approaches with genetic design has proven a powerful tool in dissecting diversity in the metabolome and has additionally enhanced our understanding of complex traits. That said, such studies have rarely been carried out in wheat. In this study, we detected 805 metabolites from wheat kernels and profiled their relative contents among 182 wheat accessions, conducting a metabolite‐based genome‐wide association study (mGWAS) utilizing 14 646 previously described polymorphic SNP markers. A total of 1098 mGWAS associations were detected with large effects, within which 26 candidate genes were tentatively designated for 42 loci. Enzymatic assay of two candidates indicated they could catalyse glucosylation and subsequent malonylation of various flavonoids and thereby the major flavonoid decoration pathway of wheat kernel was dissected. Moreover, numerous high‐confidence genes associated with metabolite contents have been provided, as well as more subdivided metabolite networks which are yet to be explored within our data. These combined efforts presented the first step towards realizing metabolomics‐associated breeding of wheat.

Grain weight (GW) is one of the component traits of wheat yield. Existing reports have shown that multiple phytohormones are involved in the regulation of GW in different crops. However, the potential role of jasmonic acid (JA) remains unclear. Here, we report that triticale grain weight 1 (tgw1) mutant, with marked reductions in both GW and JA content, is caused by a premature stop mutation in keto-acyl thiolase 2B (KAT-2B) involved in β-oxidation during JA synthesis. KAT-2B overexpression increases GW in wild type and boosts yield. Additionally, KAT-2B compliments the grain defect in tgw1 and rescues the lethal phenotype of the Arabidopsis kat2 mutant in a sucrose-free medium. Despite the suppression of JA synthesis in tgw1 mutant, ABA synthesis is upregulated, which is accompanied by enhanced expression of SAG3 and reduction of chlorophyll content in leaves. Together, these results demonstrate a role of the JA synthetic gene KAT-2B in controlling GW and its potential application value for wheat improvement.

Melatonin (Mel) is a multifunctional biomolecule found in both animals and plants. In plants, the biosynthesis of Mel from tryptophan (Trp) has been delineated to comprise of four consecutive reactions. However, while the genes encoding these enzymes in rice are well characterized no systematic evaluation of the overall pathway has, as yet, been published for wheat. In the current study, the relative contents of six Mel‐pathway‐intermediates including Trp, tryptamine (Trm), serotonin (Ser), 5‐methoxy tryptamine (5M‐Trm), N‐acetyl serotonin (NAS) and Mel, were determined in 24 independent tissues spanning the lifetime of wheat. These studies indicated that Trp was the most abundant among the six metabolites, followed by Trm and Ser. Next, the candidate genes expressing key enzymes involved in the Mel pathway were explored by means of metabolite‐based genome‐wide association study (mGWAS), wherein two TDC genes, a T5H gene and one SNAT gene were identified as being important for the accumulation of Mel pathway metabolites. Moreover, a 463‐bp insertion within the T5H gene was discovered that may be responsible for variation in Ser content. Finally, a ASMT gene was found via sequence alignment against its rice homolog. Validations of these candidate genes were performed by in vitro enzymatic reactions using proteins purified following recombinant expression in Escherichia coli, transient gene expression in tobacco, and transgenic approaches in wheat. Our results thus provide the first comprehensive investigation into the Mel pathway metabolites, and a swift candidate gene identification via forward‐genetics strategies, in common wheat.

Breaking Summer Dormancy of P. ternata 5, 9-trimethyl-12-(1-methylethyl). Our findings show that the summer dormancy of P. ternata which is a naturally evolved trait, can be removed by a single heat responsive gene. The study contributes to generating heat tolerant new Pinellia varieties with enhanced commercially valuable chemicals.