Genome-wide identification of the MCA gene family and its role in resistance to powdery mildew in wheat

Metacaspases (MCAs) play important roles in regulating plant growth and development, as well as programmed cell death under stress conditions. Based on whole-genome information, a total of 36, 10, 12, 23, 11, nine, nine, six, eight, and five MCA genes were identified in Triticum aestivum, Hordeum vulgare, Triticum urartu, Triticum dicoccoides, Aegilops tauschii, Oryza sativa, Arabidopsis thaliana, Vitis vinifera, Solanum lycopersicum, and Cucumis sativus, respectively. The gene structures, evolutionary relationships, and potential roles of TaMCAs in wheat powdery mildew resistance were systematically analyzed. Phylogenetic analysis classified MCAs into four subgroups (Class I-1, I-2, II-1, and II-2), with members within the same subgroup exhibiting highly similar gene structures. Notably, two pairs of tandemly duplicated genes (TaMCA1A-2/TaMCA1A-3 and TaMCA1B-2/TaMCA1B-3) were identified in wheat. Virus-induced gene silencing and qRT-PCR demonstrated that TaMCA4D-3, as a Class I-2 gene, positively regulates resistance to wheat powdery mildew, and subcellular localization analysis indicated that TaMCA4D-3 is localized in both the nucleus and cytoplasm. Collectively, these findings provide new insights into the classification and evolutionary relationships of the MCA gene family across plant species and elucidate the role of MCAs in wheat resistance to powdery mildew.