GENETIC ANALYSIS OF ANTHRACNOSE RESISTANCE IN OURO NEGRO, ESPLENDOR AND MAJESTOSO COMMON BEAN CULTIVARS

Authors

L. C. Costa, Universidade Federal de Lavras
E. A. Souza, Universidade Federal de LavrasFollow
R. S. Nalin, Escola Superior de Agricultura Luiz de Queiroz
M. A. P. Ramalho, Universidade Federal de Lavras
R. Pereira, Universidade Federal de Lavras

Date of this Version

3-2017

Citation

ANNUAL REPORT OF THE BEAN IMPROVEMENT COOPERATIVE, No. 60, March 2017. Published by USDA.

Comments

U.S. government work.

Abstract

INTRODUCTION Anthracnose, caused by the hemibiotrophic fungus Colletotrichum lindemuthianum (Sacc. & Magnus) Briosi & Cavara, is one of the most devastating diseases of common bean. Genetic resistance is the most effective and economical method of defence against this pathogen (Singh and Schwartz, 2010). Thus, characterization of resistant cultivars to prevalent C. lindemuthianum strains in growing region is important for choosing appropriate strategies in breeding programs to anthracnose resistance. Ouro Negro, Majestoso and Esplendor are common bean cultivars widely used by farmers in Brazil, having high resistance to different races of C. lindemuthianum predominant in the country. Therefore, this study aimed to characterize the genetic resistance of these cultivars to three different strains of C. lindemuthiam, race 65.

MATERIAL AND METHODS The study of resistance inheritance were performed in F₂ populations derived from crosses between the resistant cultivars, Ouro Negro, Majestoso and Esplendor with the susceptible cultivar, União. Allelism tests also were performed in F₂ populations derived from crosses between resistant cultivars. The strains of C. lindemuthianum, race 65 used in all these tests were: Cl1740, Cl1614 and Cl1532. The strains were inoculated in bean pod culture medium and incubated at 22°C for 10-15 days in the darkness to obtain high sporulation. Then, a suspension of 1.2 x10⁶ conidia.ml^-1 was prepared and sprayed in seedlings of parents, F1 and F2 populations derived from each cross. The inoculated plants remained in greenhouse with humidity (95%) and temperature (22°C) controlled. 10 days after inoculation, plants were visually evaluated using a scale from 1 to 9 proposed by Schoonhoven and Pastor Corrales, (1987). Plants scoring below 3 were considered resistant, whereas plants scoring more than 3 were considered susceptible. Pérola cultivar was used as susceptible control in all inoculations. The genetics analysis of F₂ populations were performed through Chi-Square Test (χ²) using Genes Software (Cruz, 2013).