TOWARDS A DEEP TRANSCRIPTOMIC ANALYSIS OF ZUCCHINI RESPONSE TO ZYMV ATTACK FOR RAPID DETECTION OF VIRUS RESISTANCE LOCI IN ZUCCHINO

Cucurbits species are economically important crops grown worldwide. In many regions, themost serious threat to their production is Zucchini yellow mosaic virus (ZYMV). The use ofresistant cultivars could be the most cost-effective and reliable approach for limiting the spread ofthis dangerous virus. A monogenetic source of resistance to ZYMV was identified in Cucurbitamoschata and introgressed in a C. pepo. However, in cultivated zucchini the major gene indicatedas Zym-1 interact with two modifier genes Zym-2 and Zym-3, making difficult the breedingresistance transfer. Until now, not effective markers associated to this resistance have been found.The aims of our work was to perform both a study of zucchini resistance response to ZYMV usinggenomic resources and to discover and validate markers for rapid detection of ZYMV resistanceloci in zucchini. To reach our goals, two C. pepo isogenic lines, susceptible and resistant to ZYMV,were inoculated and leaves samples were collected at 12 and 22 day post-inoculation (dpi). A RNAsequencing of three biological replicates for each post-inoculation time was performed. In parallelSNP unigene polymorphisms, previously discovered using a Golden Gate platform, were testedusing two segregation populations for ZYMV resistance through a High Resolution Melt (HRM)genotyping. Analysis of Differential Expressed Genes (DEGs), performed between two resistantand susceptible genotypes at two post-inoculation times, revealed a total of 1302 unique expressedgenes in resistant line. HRM analysis highlighted one SNP, significantly associated to resistance toZYMV in both populations. Gene expression differences highlight in this work between the twoisogenic lines could be used for a comprehensive study of gene expression and for discoveringexpressed SNPs in zucchini in response to ZYMV. Furthermore, this study supplies a unigenemarker closely linked to the Zym-1 gene that conferred resistance against ZYMV that might beemployed in MAS.