Abstract

MORAN GOMEZ, Yunior M et al. Evaluation of resistance to false Orobanche caused by Nocardia sp. on Nicotiana spp. cultrop [online]. 2015, vol.36, n.4, pp. 108-116. ISSN 1819-4087.

False Orobanche affects tobacco production in Cuba. Diseased plants development abundant shoot proliferation and tumour in the root, and they’re showing dwarfism and rickets. Cuban Black tobacco cultivars are susceptible to Nocardia sp., causal agent of this disease. The incorporation of resistance genes into Cuban cultivars through genetic improvement will be an important element in the strategy for integrated management of this disease. However, there were not known sources of resistance to the disease and there isn’t an available procedure for the assessment of potential resistance sources present in the tobacco germplasm of Cuba. The objective of this research is to develop a method of assessing the level of resistance to the causal agent of false Orobanche of tobacco germplasm accessions. Fourteen accessions of different species and types of tobacco were inoculated with T42 strain of Nocardia sp. From the showing of symptoms was developed an empiric visual scale for calculating the plant’s damage degree. Accessions were located into four levels of reaction (resistant, moderately resistant, moderately susceptible and susceptible) according to plant’s damage degree. Resistant genotypes were identified within the tobacco germplasm bank of Cuba. Also within susceptible evaluated cultivars , plants carrying resistance genes were found with which they could immediately begin a genetic improvement program by selection of pure lines

Keywords : bacteria; tumour; shoot proliferation; germplasm; resistance.

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