Detection of QTL associated with rust resistance using IBD-based methodologies in exogamic Eucalyptus spp. populations

Abstract

-In Brazil the rust caused by Puccinia psidii Winter stands out as the most important disease of eucalyptus. The use of resistant genotypes is the main control method, which makes the detection of markers linked to rust resistance essential to the selection of resistant genotypes. In this study, an F 1 progeny of 131 plants from interspecific crossings of Eucalyptus was used to identify markers linked to resistance genes for this pathogen. An integrated map was constructed for linkage group three based on microsatellite markers. For QTL mapping two methodologies based on alleles identical-by-descent (IBD) were used: single marker analysis of Haseman and Elston and the interval mapping procedure of Fulker and

Detection and mapping of a lethal locus in a eucalyptus hybrid population

“…Considering that an important QTL to rust resistance was mapped in the linkage group 3 (Mamani et al, 2010;Rosado et al, 2010), the lethal factor locus characterized in the present study can be especially important for Eucalyptus breeding.…”

“…On the map constructed by Brondani et al (2002) using 50 SSR markers, the number of markers per linkage group varied from two (group 3) to eight (group 10), and on the map further generated by the same authors (Brondani et al, 2006), using 230 SSR, the number of markers varied from 12 (group 3) to 25 (groups 5 and 8). Besides the low saturation of linkage group 3, it is interesting to note that it also shows a large gap in the region where Rosado et al (2010) have previously mapped a QTL for rust (Puccinia psidii) resistance. These authors suggested that the elevated segregation distortion of the microsatellite loci were due to the specific amplification of deleterious alleles linked to SSR markers.…”

“…The lethal gene was mapped 10.49 cM apart from the EMBRA 189 locus and at 12.64 cM from the EMBRA 122 locus. Based on the information provided by Rosado et al (2010), who studied this same hybrid population, the lethal locus was mapped 25 cM apart from the locus which controls the rust resistance in eucalyptus. The map constructed for linkage group 3 is consistent with the reference map of Eucalyptus (Brondani et al, 2006), showing that the proposed mapping procedure based on distortion rates is adequate.…”

“…In such context, the linkage group 3 of the Eucalyptus genome can be used as an example. In this linkage group, a QTL related to rust resistance was recently mapped and validated (Mamani et al, 2010;Rosado et al, 2010;Alves et al, 2011). However, a comparison between this linkage group and others, in many independent studies, showed that it is the group which has the largest number of distorted markers.…”

Resistance of Eucalyptus pellita to rust (Puccinia psidii)

“…However, to ensure the long-term success and to simplify the selection of resistant progeny plants, the genetic control of the trait must be known for the transfer of resistance using controlled crosses. The inheritance of rust resistance in eucalypts, studied since the early 2000s (Junghans et al 2003a, Teixeira et al 2009, Rosado et al 2010, Alves et al 2011b, has shown different models to explain the segregation patterns. In the present study, we tested three models of the genetic control of resistance based on major-effect genes to explain the resistance segregation in progenies of E. pellita (Table 2).…”