A QTL analysis of sunflower partial resistance to downy mildew (Plasmopara halstedii) and black stem (Phoma macdonaldii) by the use of recombinant inbred lines (RILs)

Abstract

Partial resistance to downy mildew ( Plasmopara halstedii) and to black stem (Phoma macdonaldii) in sunflower were investigated under natural field infection and a controlled growth chamber respectively. Genetic control for resistance to the diseases was determined in recombinant inbred lines (RILs) and their two parents, 'PAC-2' and 'RHA-266.' The experiments were undertaken in a randomized complete block design with two replications, in a field severely infected by downy mildew and in a controlled growth chamber with plants inoculated with an agressive French isolate of P. macdonaldii. Each replication consisted of three rows, 4.6-m long, giving 48 plants per RIL or parent in the field and 15 plants in the growth chamber. Genetic variability was observed among the RILs for resistance to both diseases. When 10% of the selected RILs were compared with the mean of the two parents genetic gain was significant for partial resistance to the diseases. Four putative QTLs for resistance to downy mildew on linkage groups 1, 9 and 17 were detected using composite interval mapping. The QTLs explained 54.9% of the total phenotypic variance. Major QTLs ( dmr1-1 and dmr1-2) for resistance were found on linkage group 1 with up to 31% of the phenotypic variability explained by two peaks. QTL analysis of resistance to black stem showed seven QTLs on linkage groups 3, 6, 8, 9, 11, 15 and 17. The detected QTLs together explain 92% of the phenotypic variation of the trait. Crosses between RILs contrasted for their resistance to downy mildew and black stem, and exhibiting molecular polymorphism in detected QTLs, will be made in order to focus more-precisely on the genomic region of interest.

Genotype‐isolate interaction for resistance to black stem in sunflower (Helianthus annuus)

“…Recombinant inbred lines (RILs) derived from a cross between PAC-2 and RHA266 were selected for their high partial resistance to the MP6 isolate of P. macdonaldii (Rachid Al-Chaarani et al ., 2002). Mutant lines were developed by irradiation of the AS 613 genotype with gamma rays and advanced by modified single-seed descent (SSD) with no prior selection for resistance to the disease (Sarrafi et al ., 2000).…”

“…Genetic variability for partial resistance to phoma black stem in sunflower was reported in both field (Pérès et al ., 1994) and controlled conditions (Roustaee et al ., 2000a;Rachid Al-Chaarani et al ., 2002;Bert et al ., 2004). Using parental genotypes and their F 1 hybrids, Roustaee et al .…”

“…(2000a) showed that the variation for disease severity score among genotypes studied resulted from the additive and dominant effects of genes controlling black stem partial resistance. In two independent studies under controlled conditions using seedling tests, several quantitative trait loci (QTLs) for partial resistance to phoma black stem were identified (Rachid Al-Chaarani et al ., 2002;Bert et al ., 2004). All the abovementioned genetic studies used plant materials inoculated with an aggressive French isolate of P. macdonaldii (MP6).…”

Toward Marker Assisted Selection for Fungal Disease Resistance in Sunflower. Utilization ofH. Bolanderias a Source of Resistance to Downy Mildew

“…Plarg locus, introgressed from H. argophylus, different from PL8 was mapped on LG1 (8). The first QTLs that underline disease resistance, identified in RILs and mapped on LGs 1, 9 and 17 in an AFPL based map of sunflower, have been reported by AlChaarani et al (28).…”

Genotypic variation and identification of QTLs for agronomic traits, using AFLP and SSR markers in RILs of sunflower (Helianthus annuus L.)

“…AFLP is considered to be an efficient marker technology due to its high multiple ratio (Pejic et al 1998). This technique has been used in the establishment of several genetic maps, like rice (Mackill et al 1996), maize (Castiglioni et al 1999), ryegrass (Bert et al 1999), tomato (Haanstra et al 1999), melon (Wang et al 1997), pine (Remington et al 1999), eucalyptus (Marques et al 1998), lettuce (Jeuken et al 2001) and sunflower (Flores Berrios et al 2000a;Rachid Al-Chaarani et al 2002). SSRs, called microsatellites, are also used as molecular markers.…”