Identification and Expression Analysis of Fragaria Vesca MLO Genes Involved in Interaction With Powdery Mildew (podosphaera Aphanis) - Identification and Expression Analysis of Fragaria Vesca MLO Genes Involved in Interaction With Powdery Mildew (podosphaera Aphanis) - Open Access Pub

Strawberry powdery mildew, caused by Podosphaeraaphanis is a major fungal disease that affects strawberry yield and quality. In the model plant species Arabidopsis and the crop plants barley, tomato and pea, the Mildew resistance locus O (MLO) proteins have been found to be required for powdery mildew susceptibility. The present study, based on the sequence of a wild plum (Prunus americana) MLO protein, identified 16 MLO genes within the genome of woodland strawberry, Fragaria vesca and examined their expression pattern in response to powdery mildew infection in three diploid strawberry cultivars. Phylogenetic analysis showed that the FvMLO genes can be classified into six clades. Four FvMLO genes were grouped into clade III, which comprises MLO genes from Arabidopsis, tomato and grapevine that mediate powdery mildew susceptibility. A RNA-seq analysis of two diploid strawberry cultivars, F. vescassp. vesca accession Hawaii 4 (HW) and F. vesca f. semperflorens line “Yellow Wonder 5AF7” (YW) at 1 d (1 DAI) and 8 d (8 DAI) after infection showed the expression of 12 out of the 16 FvMLO genes. The comparison of Fragments Per Kilobase of transcript per Million mapped reads (FPKM values) detected by RNA-seq and expression values of qRT-PCR for FvMLO genes showed substantial agreement. The FvMLO3 gene, which was grouped in clade III and orthologous to the Arabidopsis,tomato and grapevine genes, was highly expressed in YW compared to other FvMLO genes across varieties. The results showed that FvMLO genes can be used as potential candidates to engineer powdery mildew resistance in strawberry based on MLO suppression or genome editing. DOI10.14302/issn.2638-4469.japb-17-1838 The mildew resistance locus o (MLO) genes encode a specific class of plant-specific proteins that possess seven transmembrane helices and a C-terminal calmodulin-binding domain 1, 2. An MLO gene was first identified in barley 3 and currently, a varying number of MLO genes have been identified in Arabidopsis, Medicago truncatula, chickpea, rice, maize, wheat, soybean, cucumber, tomato, rose, grapevine, peach, apple, sweet orange, cultivated Solanaceae, Brachypodium, and Cucurbitaceae species respectively 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18. Although the biological functions of MLO genes are not yet completely known, they act as suppressors of defense responses. The mutant MLO genes confer durable and broad spectrum powdery mildew resistance in monocots and dicots and the functions of these genes are highly conserved in the plant powdery mildew interactions. In barley, the