Comparison of Positions of QTLs Conferring Resistance to <i>Xanthomonas campestris</i> pv. <i>campestris</i> in <i>Brassica oleracea</i>

Abstract

Black rot, caused by Xanthomonas campestris pv. campestris (Xcc) is possibly the most important disease of Brassica worldwide. To compare chromosomal positions of Xcc resistance loci in Brassica oleracea between the present and published studies and to develop marker assisted selection (MAS) to resistance against Xcc race 1, we constructed a B. oleracea map, including pW, pX and BoCL markers that were closely linked to previously reported Xcc resistance QTLs. We also analyzed Xcc resistance QTLs by improving our previously reported map derived from the cross of a susceptible double-haploid line (GC P09) with a resistant double-haploid line (Reiho P01). In the nine linkage groups obtained (C1-C9), the major QTL, XccBo(Reiho)2, was derived from Reiho with a maximum LOD score (7.7) in C8. The QTL (LOD 4.4) located in C9, XccBo(GC)1 was derived from the susceptible GC. The other QTL (LOD 4.4), XccBo(Reiho)1, was found in C5. Based on common markers, it was possible to compare our finding Xcc resistance QTLs with the B. oleraceaXcc loci reported by previous authors; XccBo(Reiho)1 and XccBo(GC)1 may be identical to the Xcc resistance QTLs reported previously or a different member contained in the same resistance gene cluster. Our map includes public SSR markers linked to Xcc resistance genes that will promote pyramiding Xcc resistance genes in B. oleracea. The present study will also contribute to a better understanding of genetic control of Xcc resistance.

Screening of Cabbage (Brassica oleracea L.) Germplasm for Resistance to Black Rot

“…This result is consistent with previous report as described the race-specific resistance against Xcc in Brassica species by Ignatov et al (1998). Besides, Tonu et al (2013) also reported black rot resistance in B. oleracea in particular to Xcc race 3 and race 5. It should be noted that the phenotypic screening results revealed SCNU-C-4059 as resistant lines against race 7 but none of the tested markers correlated with the phenotype except BoGMS0971 which showed only 36% adaptability with bioassay results (Table 3).…”

“…Interestingly, the tested polymorphic marker BnGMS301 located on chromosome C01. Tonu et al (2013) found XccBo(Reiho)2 on chromosome C08 as the major locus for black rot resistance in cabbage and the SSR marker BoGMS0971 was closely linked to it. The remaining two SSR markers namely BoESSR291 and OI10G06 were linked to the minor QTLs (BRQTL-C3 and BRQTL-C6, respectively) The Brassica oleracea Genome Database (Bolbase).…”

“…This pathogen can enter into the leaf via insects, wounded tissues and hydathodes (leaf margin) and spreads through vascular tissues (Tonu et al 2013). Xcc can spread via rain, wind, insects, agricultural equipments and irrigation water (Sharma et al 2017).…”

“…Xcc can spread via rain, wind, insects, agricultural equipments and irrigation water (Sharma et al 2017). The characteristic disease symptoms are V-shaped chlorotic lesions at the leaf margins, necrotic and darkened veins which reduce the quality and production (Williams 1980;Kifuji et al 2013;Tonu et al 2013;Vicente and Holub 2013;Lee et al 2015). In favorable condition, black rot disease can reduce crop yield more than 50% (Williams 1980).…”

Testing of Inoculation Methods and Susceptibility Testing of Perspective Cabbage Breeding Lines (Brassica Oleracea convar. Capitata) to the Black Rot Disease Caused by Xanthomonas Campestris pv. Campestris

“…The available sources of resistance are limited and often race-specific (Ignatov et al, 1998;Tonu et al, 2013). For the species B. oleracea (genome CC), resistance for predominant races is rare or only partial.…”