Introgression of Black Rot Resistance from Brassica carinata to Cauliflower (Brassica oleracea botrytis Group) through Embryo Rescue

Abstract

Black rot caused by Xanthomonas campestris pv. campestris (Xcc) is a very important disease of cauliflower (Brassica oleracea botrytis group) resulting into 10–50% yield losses every year. Since there is a dearth of availability of resistance to black rot disease in B. oleracea (C genome), therefore exploration of A and B genomes was inevitable as they have been reported to be potential reservoirs of gene(s) for resistance to black rot. To utilize these sources, interspecific hybrid and backcross progeny (B1) were generated between cauliflower “Pusa Sharad” and Ethiopian mustard “NPC-9” employing in vitro embryo rescue technique. Direct ovule culture method was better than siliqua culture under different temperature regime periods. Hybridity testing of F1 inter-specific plants was carried out using co-dominant SSR marker and Brassica B and C genome-specific (DB and DC) primers. Meiosis in the di-genomic (BCC) interspecific hybrid of B. oleracea botrytis group (2n = 18, CC) × B. carinata (2n = 4x = 34, BBCC) was higly disorganized and cytological analysis of pollen mother cells revealed chromosomes 2n = 26 at metaphase-I. Fertile giant pollen grain formation was observed frequently in interspecific F1 hybrid and BC1 plants. The F1 inter-specific plants were found to be resistant to Xcc race 1. Segregation distortion was observed in BC1 generation for black rot resistance and different morphological traits. The At1g70610 marker analysis confirmed successful introgression of black rot resistance in interspecific BC1 population. This effort will go a long way in pyramiding gene(s) for resistance against black rot in Cole crops, especially cauliflower and cabbage for developing durable resistance, thus minimize dependency on bactericides.

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

“…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).…”

An update on the arsenal: mining resistance genes for disease management of Brassica crops in the genomic era

“…Although resistance genes are far from being isolated, some molecular markers closely linked to them have been widely adopted in MAS. Kalia et al 46 converted the formerly developed RAPD and inter-simple sequence repeat 44,47 developed markers linked to BR resistance, which were further used in the selection of introgression lines (ILs) from B. carinata to cauliflower.…”

“…The progenies displayed resistance to both races. Similarly, Sharma et al 47 successfully transferred BR resistance from B. carinata to cauliflower. In addition, distant hybridization has been used by breeders to generate novel resistant germplasms.…”

“…b A combined use of microspore culture and MAS helps promote the breeding cycle in B. oleracea107 . c BR resistance introgression from B. carinata to B. oleracea using distant hybridizing and embryo rescue47 . d SNP-based high-throughput KASP markers prove efficient and cost saving in genotyping during MAS in B. rapa30 .…”

Interspecific Hybridization for Brassica Crop Improvement

“…Resistance in 100% of BC1 progeny was successfully demonstrated in hybrids obtained by hand crossing and embryo rescue between B. carinata (donor) × B. oleracea [69]. Other cases of resistance transfer include transfer of blackrot resistance from B. carinata to B. oleracea [70], resistance to Brassica leaf blight caused by Alternaria brassicae from B. hirta to B. juncea [71] and transfer of powdery mildew resistance from B. carinata to B. oleracea through embryo rescue followed by backcrossing to B. oleracea [69].…”