Reaction of coffee genotypes to different populations of Meloidogyne spp.: detection of a naturally virulent M. exigua population

Abstract

The reaction of seven genotypes of Coffea arabica to 10 Meloidogyne spp. populations collected mainly from coffee plantations in Brazil and Costa Rica was evaluated under greenhouse conditions. The inoculum consisted of 10,000 eggs per plant. Evaluations were done 8 months after inoculations considering the root fresh weight, gall and egg mass indices, number of eggs per gram of root and reproduction factor (RF). The cultivars Obatã IAC 1669-20, Sarchimor IAC 4361 and Tupi Amarelo IAC 5111 exhibited susceptibility to the four Brazilian M. exigua populations tested. However, cv. Tupi Vermelho IAC 1669-33 revealed resistance (RF value of 0.7) to the M. exigua population from Lavras, Minas Gerais State, Brazil. A population of M. exigua from Bom Jesus de Itabapoana, Rio de Janeiro State, Brazil, was highly virulent on cv. IAPAR 59 (RF= 165.7), bearing resistance gene Mex-1, and was also virulent on genotype Paraíso (H 419-5-4-5-2) (RF=396.2). A Meloidogyne sp. population on coffee from Garça, São Paulo State, Brazil, reproduced at low rates (RF ranging from 0.1 to 3.9) on all genotypes. All tested cultivars were susceptible to M. incognita and M. paranaensis. M. mayaguensis of guava from Paraná State, Brazil, reproduced at low rates in all coffee genotypes; however, another population of coffee, from Costa Rica, was more aggressive and showed RF value that ranged from 0.8 to 12.4. Results of this study point for the first time to the ability of a naturally occurring M. exigua population to overcome the resistance conferred by the Mex-1 gene.

Genetic Gain in the Resistance of Arabica Coffee Progenies to Root‐Knot Nematode

“…The correlations between GI and nematode variables were high. Muniz et al (2009) studied different populations of M. exigua and found significant genotypic correlations between GI and RF (r = 0.59-0.69). Muniz et al (2009) studied different populations of M. exigua and found significant genotypic correlations between GI and RF (r = 0.59-0.69).…”

“…Numerous studies have used RF as a parameter for classifying plant responses to nematodes (Carneiro et al, 2008;Muniz et al, 2009). The use of this parameter for qualitative classification of progenies might lead to inconsistencies, since closely related RF values in the range of 0.95 to 1.5 can have distinct resistance classifications.…”

“…Rezende et al (2013) found a 0.94 correlation coefficient between the number of galls and eggs per gram of roots. Muniz et al (2009) studied different populations of M. exigua and found significant genotypic correlations between GI and RF (r = 0.59-0.69).…”

Agronomic characterization and responses to coffeeleaf rust in coffee progenies resistant to the gall nematode Meloidogyne exigua

“…et Br. (COSTA et al, 2007;PAIVA et al, 2010;DEL GROSSI et al, 2013) and to gall nematodesMeloidogyne spp. (BARBOSA et al, 2010;REZENDE et al, 2013).…”

“…(BARBOSA et al, 2010;REZENDE et al, 2013). Currently, these pathogens are the main phytosanitary problems for coffee plants and cause serious economic losses to coffee growers PEREIRA, 1998;MUNIZ et al, 2009). …”