Screening mutant sunflower populations for the identification of new genetic diversity associated to Sclerotinia Head Rot Resistance

FASS M.; MUÑOZ M.; PUEBLA A.; HOPP HE; HEINZ RA; LIA VV; PANIEGO N.

Congreso; 11th International Plant Molecular Biology Congress; 2015

Sclerotinia Head Rot (SHR), caused by the necrotophic fungus Sclerotiniasclerotiorum, is one of the most damaging diseases in sunflower and can lead tomajor production losses. Since resistance to this pathogen has additive geneaction and is quantitatively inherited, the defense mechanisms are complex.Previous work by our group has identified genes and genomic regions underlyingresistance using a variety of approaches, including biparental Quantitative TraitLoci (QTL) mapping, Association Mapping and analysis of differential expression inresistant and susceptible genotypes infected with S. sclerotiorum. The goal of thisstudy is to infer the function and relevance of these candidate genes during thedefense response by the screening and analysis of two TILLING-populations,mutagenized with ethylmethane sulfonate (EMS) or ionizing radiation, consisting of1121 and 2178 individuals, respectively. The search of mutants is accomplished bytwo alternative methods: 1) PCR-amplification of each candidate gene,heteroduplex cleavage through the enzyme CEL1 and fragment separation usingcapillary electrophoresis; or 2) by means of targeted enrichment by microfluidics based multiplex PCR sequencing (mmPCR-seq). The first method has led to apoint mutation within one gene, which contains a calcium binding domain (EF-handmotif) and is expressed in stamen and pollen. These screening strategies forecasta quick identification of new mutants on the selected candidate genes enabling afurther step to the understanding of the plant-pathogen defense response.