Resumo

CASTANEDA, Rossmary; RAMIS, Catalina  e  MASELLI, Anna. Evaluation of resistance to common bacterial blight of black bean in the family F_2:4 of Phaseolus vulgaris L.. Agronomía Trop. [online]. 2014, vol.64, n.1-2, pp.7-18. ISSN 0002-192X.

The black bean (Phaseolus vulgaris L.) is one of the staples in the venezuelan diet. Productivity is seriously affected by the common bacterial blight caused by Xanthomonas phaseoli. Incorporating resistance genes through breeding programs is presented as an alternative control. In order to evaluate the resistance to common bacterial blight, black beans families F_2:4 were studied, from crossing XAN-154 and MEM-0301013. The plants were inoculated with Tucutunemo strain, using the multiple needle method on protophylls. The variables evaluated, spot size (mm) and percentage of leaf area affected (% FAA) allowed us to study the disease advance. For the moment of maximum development of disease, 25 days after plants inoculation (DDI), the frequency distribution of the different degrees of reaction (scale from 1 to 9) was determined. The goodness of fit test (χ²) was performed, yielding that segregation observed corresponded to a single dominant gene in F₂. Two families F_2:4 (16 and 36) were found completely resistant, the father XAN-154 and genotype XAN-149 showed high resistance. Most families F_2:4 showed high to moderate resistance. The resistance provided by the parent XAN-154, could be used as a source of monogenic resistance for the conformation of other populations in genetic breeding. There was evidence of the presence of polygenes for resistance possibly provided by both parents; these genes of smaller effect, could be used in future breeding programs.

Palavras-chave : Xanthomonas phaseoli; inheritance; inoculation.

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