Identification of a recessive gene RgM4G52 conferring red glume, stem, and rachis in a Triticum boeoticum mutant

Anthocyanins are plant secondary metabolites belonging to the polyphenol class of natural water-soluble phytopigments. The accumulation of anthocyanins in different plant tissues can improve plant survival under adverse conditions. In addition, plants with the resulting colorful morphology can be utilized as landscape plants. <i>Triticum boeoticum</i> (syn. <i>Triticum monococcum</i> ssp. <i>aegilopoides</i>, 2n=2x=14, A^bA^b) serves as a valuable genetic resource for the improvement of its close relative common wheat in terms of enhancing resilience to various biotic and abiotic stresses. In our previous study, the EMS-mutagenized mutant Z2921 with a red glume, stem, and rachis was generated from <i>T. boeoticum</i> G52, which has a green glume, stem, and rachis. In this study, the F₁, F₂, and F_2:3 generations of a cross between mutant-type Z2921 and wild-type G52 were developed. A single recessive gene, tentatively designated <i>RgM4G52</i>, was identified in Z2921 via genetic analysis. Using bulked segregant exome capture sequencing (BSE-Seq) analysis, <i>RgM4G52</i> was mapped to chromosome 6AL and was flanked by the markers <i>KASP-58</i> and <i>KASP-26</i> within a 3.40-cM genetic interval corresponding to 1.71-Mb and 1.61-Mb physical regions in the Chinese Spring (IWGSC RefSeq v1.1) and <i>Triticum boeoticum</i> (TA299) reference genomes, respectively, in which seven and four genes related to anthocyanin synthesis development were annotated. Unlike previously reported color morphology-related genes, <i>RgM4G52</i> is a recessive gene that can simultaneously control the color of glumes, stems, and rachis in wild einkorn. In addition, a synthetic <i>Triticum dicoccum</i>-<i>T. boeoticum</i> amphiploid Syn-ABA^b-34, derived from the colchicine treatment of F₁ hybrids between tetraploid wheat PI 352367 (<i>T. dicoccum</i>, AABB) and Z2921, expressed the red stems of Z2921. The flanking markers of <i>RgM4G52</i> developed in this study could be useful for developing additional common wheat lines with red stems, laying the foundation for marker-assisted breeding and the fine mapping of <i>RgM4G52</i>.