A genome-wide identification and comparative analysis of the lentil <i>MLO</i> genes

<div><p>Powdery mildew is a widespread fungal plant disease that can cause significant losses in many crops. Some <i>MLO</i> genes (<i>Mildew resistance locus O</i>) have proved to confer a durable resistance to powdery mildew in several species. Resistance granted by the <i>MLO</i> gene family members has prompted an increasing interest in characterizing these genes and implementing their use in plant breeding. Lentil (<i>Lens culinaris</i> Medik.) is a widely grown food legume almost exclusively consumed as dry seed with an average world production of 4.5 million tons. Powdery mildew causes severe losses on certain lentil cultivars under particular environmental conditions. Data mining of the lentil CDC Redberry draft genome allowed to identify up to 15 gene sequences with homology to known <i>MLO</i> genes, designated as <i>LcMLOs</i>. Further characterization of these gene sequences and their deduced protein sequences demonstrated conformity with key MLO protein characteristics such as the presence of transmembrane and calmodulin binding domains, as well as that of other conserved motifs. Phylogenetic and other comparative analyses revealed that <i>LcMLO1</i> and <i>LcMLO3</i> are the most likely gene orthologs related to powdery mildew response in other species, sharing a high similarity with other known resistance genes of dicot species, such as pea <i>PsMLO1</i> and <i>Medicago truncatula MtMLO1</i> and <i>MtMLO3</i>. Sets of primers were designed as tools to PCR amplify the genomic sequences of <i>LcMLO1</i> and <i>LcMLO3</i>, also to screen lentil germplasm in search of resistance mutants. Primers were used to obtain the complete sequences of these two genes in all of the six wild lentil relatives. Respective to each gene, all <i>Lens</i> sequences shared a high similarity. Likewise, we used these primers to screen a working collection of 58 cultivated and 23 wild lentil accessions in search of length polymorphisms present in these two genes. All these data widen the insights on this gene family and can be useful for breeding programs in lentil and close related species.</p>