Characterization of a single recessive yield trait mutant with elevated endogenous ABA concentration and deformed grains, spikelets and leaves

The characterization of yield trait mutants is important for understanding the regulation of grain yield formation in staple food crops. Meh0239 is a yield trait-related mutant identified from a mutant library of the common wheat cultivar Wangshuibai created by ethylmethyl sulfide (EMS) treatment of dry seeds. To shed some light on the nature of this mutation, it was investigated morphologically, physiologically, anatomically and genetically. The mutant plant showed obvious phenotypic differences in comparison with the wild type, starting at the seedling stage, including reduced plant height, wider and shorter leaves, shortened spikes, spikelets and grains and a more compact spikelet distribution. Also, seeds produced in the mutant germinated more slowly. Meh0239 contained a significantly higher level of abscisic acid (ABA) but lower levels of indole-3-acetic acid (IAA), methyl jasmonate (MeJA) and zeatin riboside (ZR) in flag leaves. Cells of all types in the leaf epidermis appeared shorter along the axial direction. The bulliform cells and long cells on the adaxial leaf surface were abnormal in shape. A genetic analysis using two F2 segregating populations indicated that a single recessive mutation in wheat chromosome 7DS, about 3.1 cM distal from Xwmc506, caused these variations. Because of the pleiotropic nature of this gene and its relation with yield trait formation, we named it Yt1 for yield trait related 1.

Research highlights▶ Meh0239 is a novel yield-trait related mutant of common wheat. ▶ Meh0239 is phenotypically different from known yield gene mutants in cereals. ▶ The phenotypic variations are associated with abnormal leaf epidermis cells. ▶ The mutation is related to changed endogenous hormone level, particularly ABA. ▶ The mutant results from a recessive mutation on chromosome 7DS.