Abstract
Black rot is a destructive disease that affects B. oleracea crops, causing significant losses to growers throughout the world. The purpose of this study was to screen out new sources resistant to Xanthomonas campestris pv. campestris race 4 (Xcc4) in 26 cauliflower and six related wild species, and to assess the inheritance of resistance. The results indicate that most of the tested accessions were susceptible or had intermediate resistance, except the Boc4601 (a cauliflower stable inbred line) and PI435896, UNICT5168, and UNICT5169 (wild accessions). Among them, UNICT5169 (Brassica montana) and PI435896 (Brassica balearica) showed the strongest resistance to Xcc4, with significantly lower disease index (DI), area of the infected part (AIP) and proportion of the infected part to the total leaf area (PTL) values. UNICT 5169 was selected as an Xcc4-resistant parent because of its relatively good cross seed-setting rate with cauliflower cultivars. F1 hybrids were successfully produced between this wild resistant accession (UNICT 5169) and one susceptible cauliflower breeding line (Boc3202-4), indicating the potential transferability of this resistance to cauliflower. The results of the symptoms severity evaluation of the F2 population indicate that Xcc4 resistance in UNICT5169 is a quantitative trait, which guides future resistance gene location and black rot resistance breeding.
Highlights
Cauliflower (Brassica oleracea var. botrytis) is an important vegetable, which is widely grown inChina, India, Italy, and other countries located mainly in Asia and Europe [1,2,3]
Black rot is a destructive disease caused by Xanthomonas campestris pv. campestris (Xcc), which reduces the performance, yield, and quality of B. oleracea crops [4,5,6,7,8]
A total of 32 accessions were screened for black rot resistance (Table 1), including 26 cauliflower materials and six related wild species (B. balearica, B. incana, B. insularis, B. macrocarpa, B. montana, and B. villosa)
Summary
Cauliflower (Brassica oleracea var. botrytis) is an important vegetable, which is widely grown inChina, India, Italy, and other countries located mainly in Asia and Europe [1,2,3]. Campestris (Xcc), which reduces the performance, yield, and quality of B. oleracea crops [4,5,6,7,8]. This pathogen invades host plants through hydathodes or wounds, with rapid multiplication that produces high amounts of extracellular polysaccharides and xanthan, clogging the vascular system and, thereby forming typical “V”-shaped chlorotic lesions along the edges of the leaves [9]. Pesticide is ineffective because of the potential hazards of pesticide residue and environmental pollution; breeding Xcc-resistant varieties is undoubtedly the most effective way to control black rot disease
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