QTLs for resistance to powdery mildew in pepper under natural and artificial infections

Abstract

Epidemics of powdery mildew due to Leveillula taurica is an increasing problem in pepper production areas, particularly in coastal regions or greenhouse cultivation. The highly resistant genitor 'H3' was submitted to genetic analysis and QTL mapping in order to promote the introgression of its oligogenic resistance into large and sweet-fruited cultivars. The doubled-haploid progeny from the cross 'H3' (resistant) by 'Vania' (susceptible) was tested for resistance under both natural field infection and artificial inoculation tests, and QTL detection was compared for those two methods. Seven genomic regions including additive QTLs and epistatic interactions were detected, explaining altogether the major part of genotypic variance. Two genomic regions were common to both the evaluation methods, whereas other QTLs were method-specific, reflecting the environment dependence of powdery mildew epidemics. Orthologies with tomato genomic regions carrying resistance genes to L. taurica and Oidium lycopersicum were revealed by comparative mapping with pepper. Tight linkages between the detected QTLs and virus resistance or fruit color traits in pepper were also shown, which adds to the agronomic importance of these regions in pepper breeding programs.

Genetic dissection of agronomic traits in Capsicum baccatum var. pendulum

“…Most QTL studies in pepper have focused on commercial traits, such as fruit and production traits (Rao et al, 2003;Zygier et al, 2005;Barchi et al, 2009;Lee et al, 2011;Alimi et al, 2013) as well as studies related to identification of QTL associated with resistance to diseases (Lefebvre et al, 2003;Mimura et al, 2009;Kim et al, 2011). A limited number of studies have identified QTL associated with vegetative parts of the plant (leaves, stem internodes, and petioles) (Barchi et al, M.M.…”

Mapping for Axillary Shooting, Flowering Date, Primary Axis Length, and Number of Leaves in Pepper (Capsicum annuum)

“…Hence, the inheritance of these traits has been extensively studied and the quantitative trait loci (QTLs) that contribute to disease resistance and fruit traits have been reported (Ben Chaim et al, 2001a, 2001bLefebvre et al, 2003;Minamiyama et al, 2005Minamiyama et al, , 2007Popovsky and Paran, 2000;Thabuis et al, 2003;Voorrips et al, 2004). In addition to the above-mentioned traits, axillary shooting, flowering date, primary axis length, and number of leaves are also important for pepper production.…”

Statistical Modeling of Epistasis and Linkage Decay using Logic Regression

“…Numerous QTL and genic studies have identified multiple loci involved in the expression of a single trait (Calborg and Haley 2004). In addition, interval mapping and composite interval mapping have been used successfully to identify QTL associated with specific phenotypes that led to the identification of statistically significant interactions (Shook and Johnson 1999;Lefebvre et al 2003;Ma et al 2006). However, in all these cases, additional studies were required to ascertain the actual genetic model defining the interaction of the various loci.…”