Genome-wide characterization of MLO family genes in bread wheat and Arabidopsis thaliana shed light on their role in growth and development, and resistance to powdery mildew, biotic and abiotic stresses

Powdery mildew (PM), caused by the fungus, Blumeria graminis tritici is a devastating and notorious disease that is prevalent across the globe and causes up to 62% of yield losses in wheat. The well-known 68 PM resistance loci (Pm1 -Pm68) are not long-lasting and break down when new races of pathogens interact with host plants. The editing of three known MLO genes through CRISPR/Cas9 has conferred resistance against PM. However, only seven MLO genes were known in wheat to date. Taking advantage of IWGSC Ref-seq v2.1 and using the gold-standard analysis pipeline that we have designed, we expanded this number to 47 and reported 40 additional potential CRISPR targets that can be used to develop PM resistance, disease resistance, and abiotic stress tolerance in wheat. We also performed phylogenetic, gene structure, and MOTIF analysis that indicated conserved evolutionary patterns, and the phylogenetic pattern was strongly supported by gene structure and MOTIF analysis. The gene duplication and evolution analysis showed that segmental duplications were prevalent and purifying selection operated during evolution. Comparative phylogenetic analysis with Arabidopsis thaliana and Brachypodium distachyon depicted that clade IV was exclusive for monocots. Finally, MLOs are expressed under powdery mildew, rusts, head blight, abiotic stresses, growth, and development thus TraesMLOs have a potential role in wheat under these conditions. Therefore, we hope that the MLO genes identified in this study will be edited through CRISPR/Cas9 or will be overexpressed to develop PM and disease-resistant and abiotic stress-tolerant wheat. Additionally, we performed most of the above-mentioned analyses for Arabidopsis thaliana, revised its numbers as compared to the TAIR database, and updated it outdated analysis performed in 2003. ### Competing Interest Statement The authors have declared no competing interest.