Black Rot is a major disease problem for brassica growers in countries in East Africa such as Kenya. The seed-borne disease is caused by bacteria which penetrate the leaves and cause spreading yellow lesions. Affected leaves can drop prematurely and plants can die. Black Rot is a major constraint on cabbage & kale production in East Africa and farm level incidence as high as 100% has been recorded. Plant breeding for durable resistance, involving several genes, would provide a sustainable solution to this problem. However little is currently known about this type of resistance.
In previous research we have identified good sources of resistance and mapped the location of the major genetic components. In this projectwe will exploit exciting new developments in Brassica genomics to characterise the resistance and identify the genes involved. We have identified new markers linked to the resistance from knowledge of the Brassica genome sequence. These Single Nucleotide Polymorphism (SNP) markers allow us to fine-map the region of the Brassica genome where the resistance is located, allowing plant breeders to more rapidly and efficiently transfer the resistance into other varieties. We have screened a wide range of wild species of Brassicas related to cabbages,kales and broccoli and found very little resistance to Black Rot, so this resistance could have a useful practical application. We have also carried out a survey of the bacterium which causes the disease, Xanthomonas campestris pv. campestris, in East Africa so that farmers and breeders can be informed about the pathotypes causing the disease in ther area.
Key practical outcomes of this work will be resistant plant material with tightly linked molecular markers, candidate resistance genes and information on the natural variation in the pathogen that could be exploited in plant breeding to provide durable resistance to a very significant plant disease.
Harper Adams University
University of Warwick, Fera, CABI, KARI
MULEMA JMK, VICENTE JG, PINK DAC, JACKSON A, CHACHA DO, WASILWA L, KINYUA ZM, KARANJA DK, HOLUB EB, HAND P (2012). Characterization of isolates that cause Black rot of crucifers in East Africa. Eur. J. Plant Pathol. 133(2): 427-438. DOI 10.1007/s10658-011-9916-x
Hand P & Mulema J (2011). Developing Black Rot Resistant Brassicas for East African Farmers. UK Brassica Research Community Annual Conference, May 2011, Nottingham University.