Detection and verification of quantitative trait loci for resistance to Dothistroma needle blight in Pinus radiata

Abstract

Six related radiata pine ( Pinus radiata) full-sib families were used to detect and independently verify quantitative trait loci (QTLs) for resistance to Dothistroma needle blight, caused by Dothistroma septospora. The detection families had from 26 to 30 individuals each, and had either a common maternal (31053) or paternal (31032) parent; one family (cross 4) consisted of progeny from both parents, 31053 x 31032. Approximately 200 additional progeny from cross 4 were clonally replicated and planted at two sites, with at least five to seven ramets of each individual per site. Marker segregation data were collected from a total of 250 RFLP and microsatellite markers, and single factor ANOVAs were conducted separately for each family and marker. A number of putative associations were observed, some across more than one family. Permutation tests were used to confirm expected probabilities of multiple associations based on chance alone. Seven markers representing at least four QTLs for resistance to Dothistroma were identified as being significant in more than one family; one of these was significant at P<0.05 in three families and highly significant at P<0.01 in a fourth. Further confirmation was obtained by testing those markers that were significant in more than one of the detection families (or highly significant in cross 4) in the clonally replicated progeny from cross 4. Four QTL positions were verified in the clonal populations, with a total percent variation accounted for of 12.5.

Establishment and optimization of ISSR and SAMPL molecular markers as a tool for breeding programs of Pinus radiata

“…Studies in the same species have detected up to 34 % of segregation distortion (Kuang et al 1999), however the smaller number of offspring compared to earlier studies (Wilcox et al 2001, Devey et al 2004 could be responsible for the low representativeness of the expected allelic proportions.…”

“…Polymorphic information, mode of inheritance, genomic size and complexity are factors that influence the development of a particular technique and the selection of informative molecular markers (Plomion et al 2007). Among the molecular techniques implemented for P. radiata are restriction fragment length polymorphism (RFLP; Devey et al 2004), random amplified polymorphic DNA (RAPD; Kuang et al 1999, Wilcox et al 2001, amplified fragment length polymorphism (AFLP; Wilcox et al 2001), simple sequence repeat (SSR; Fisher et al 1998, Devey et al 2002, Chagné et al 2004) and single-nucleotide polymorphism (SNP; Dillon et al 2010).…”

A review of Pinaceae resistance mechanisms against needle and shoot pathogens with a focus on the Dothistroma–Pinus interaction

“…However, Franich et al (1986) reported an opposite effect and therefore concluded that dothistromin-induced lesion length was not a good measure of field resistance in Pinus radiata. Devey et al (2004) were able to identify quantitative trait loci for DNB resistance in P. radiata in Australia, which can be used as markers for DNB resistance and should contribute to future resistance breeding.…”

Genetic structure of the foliar pathogen Dothistroma septosporum in northwest British Columbia suggests recombination and high gene flow.

“…Currently, the disease is managed in Southern Hemisphere plantations by the aerial application of copper fungicides (Bradshaw 2004), which can be costly and have detrimental effects on the environment (Devey et al 2004). Reduction in disease is also obtained through breeding programs for Dothistroma septosporum resistant pine strains.…”

“…Quantitative traits can be selected for through long term breeding programs, or by selecting individuals that have a genetic marker associated with quantitative resistance (Devey et al 2004). Breeding programs have been underway in New Zealand for some time now and have been effective in reducing overall losses (Bradshaw 2004).…”