Genetic architecture of factors underlying partial resistance to Alternaria leaf blight in carrot

Abstract

In most production areas, Alternaria leaf blight (ALB) is recognized as the most common and destructive foliage disease in carrot. To assess the genetic architecture of carrot ALB resistance, two parental coupling maps were developed with similar number of dominant markers (around 70), sizes (around 650 cM), densities (around 9.5 cM), and marker composition. The F(2:3) progenies were evaluated in field and tunnel for two scoring dates. The continuous distribution of the disease severity value indicated that ALB resistance is under polygenic control. Three QTLs regions were found on three linkage groups. Two of them were tunnel or field specific and were detected only at the second screening date suggesting that the expression of these two QTLs regions involved in resistance to Alternaria dauci might depend on environment and delay after infection.

Evaluating aggressiveness and host range of Alternaria dauci in a controlled environment

“…Caporal) were used (Table 1). FRA001 and FRA017 were chosen as reference isolates because of their use in previous studies (Pawelec et al, 2006;Boedo et al, 2008Boedo et al, , 2010Le Clerc et al, 2009). For production of conidia, fungal isolates were grown in Petri dishes on V8 juice agar medium (200 mL V8 vegetable juice, 3 g CaCO 3 , 15 g agar L )1 , pH 6AE8), incubated in darkness at 22 ± 2°C for 7 days, and then exposed to 12 h nearultraviolet light (Philips, TL-D 36 W) alternating with 12 h darkness at 22 ± 2°C for 10-15 days.…”

“…, 2006; Boedo et al. , 2008, 2010; Le Clerc et al. , 2009), only one or two isolates were generally used.…”

“…Differences in aggressiveness among A. dauci isolates collected worldwide has, however, never been investigated. In previous papers focusing on different aspects of A. dauci -carrot interactions, such as infection processes, ALB resistance evaluation or genetic determinism (Dugdale et al, 2000;Pawelec et al, 2006;Boedo et al, 2008Boedo et al, , 2010Le Clerc et al, 2009), only one or two isolates were generally used. It would be very important to assess the aggressiveness of A. dauci isolates before using them in future studies.…”

“…The first objective of the present study was to compare the aggressiveness of a set of A. dauci isolates after inoculation of a susceptible carrot cultivar which had previously been used as a positive disease control in several studies (Ben-Noon et al, 2001;Pawelec et al, 2006;Boedo et al, 2008Boedo et al, , 2010Le Clerc et al, 2009). For that purpose, A. dauci isolates were chosen from a worldwide collection of this fungal species to represent high diversity according to geographic origin and polymorphism in the intergenic spacer (IGS) regions of nuclear rDNA.…”

Characterization of Isolates of Alternaria and Fusarium Found in Carrot From Different Ecological and Geographic Zones

“…Первый анализ генетики устойчивости мор-кови столовой к данному заболева-нию описан Le Clerc V. и др. 2009 [22]. Полевой и тепличный скринин-ги с использованием шкалы болез-ни является рутинной процедурой для выявления устойчивых геноти-пов [23,21] …”