Pathogenic Variability of Isolates of Pseudocercospora griseola, the Cause of Common Bean Angular Leaf Spot, and its Implications for Resistance Breeding

Abstract

The pathogenic variability was evaluated of 48 Pseudocercospora griseola isolates collected in the State of Minas Gerais, Brazil. Isolates were inoculated to a set of 12 international differential cultivars in a greenhouse. Ten pathotypes (55‐15, 63‐7, 63‐15, 63‐23, 63‐25, 63‐27, 63‐31, 63‐47, 63‐55 and 63‐63) were identified, showing the great pathogenic variability of this fungus in Minas Gerais State. Pathotypes 55‐15, 63‐15, 63‐25 and 63‐27 had not previously been reported in the State. Of the 48 isolates, all except pathotype 55‐1547 induced a compatible reaction with all cultivars from the Andean group. Isolates were highly pathogenic in both Andean and Mesoamerican cultivars, thus being classified as Mesoamerican pathotypes. Pathotype 63‐63 was the most widespread, and overcame the resistance genes present in all differential cultivars.

Influência do ambiente em cultivares de feijoeiro-comum em cerrado com baixa altitude

“…No caso de reação à mancha angular, na interação, observa-se que podem ocorrer raças diferentes do patógeno nos locais (Pereira et al, 2004;Silva et al, 2006), pois esse patógeno possui ampla variabilidade patogênica (Satorato, 2002;Silva et al, 2008).…”

“…O método possibilita ainda o detalhamento dessa informação para ambientes favoráveis e desfavoráveis. Esse método tem sido utilizado em diversas culturas, como algodão (Silva Filho et al, 2008), arroz (Soares et al, 2007) e milho (Cargnelutti Filho et al, 2007), além do feijoeiro-comum (Melo et al, 2007;Pereira et al, 2009), mostrando facilidade de utilização e identificação dos genótipos mais estáveis e adaptados entre os mais produtivos. Entretanto, poucos estudos dessa natureza foram realizados com o feijoeiro-comum na Região Central do Brasil (Pereira et al, 2009) e não existem estudos específicos para regiões de cerrado com baixa altitude.…”

Eight cycles of recurrent selection for resistance to angular leaf spot in common bean

“…The primary means of control is the use of resistant cultivars (Silva et al 2006, Couto et al 2008, Ragagnin et al 2009). However, the difficulty of obtaining lines with durable resistance is unquestioned, mainly due to the proven existence of numerous races of the pathogen (Sartorato and Alzate Marín 2004, Sartorato 2004, Silva et al 2008, Balbi et al 2009). The information available about the genetic control of resistance indicates that several genes must be involved (Miklas et al 2006, Amaro et al 2007, Mahuku et al 2004, Mahuku et al 2009.…”

Characterization of the Angular Leaf Spot Resistance Gene Present in Common Bean Cultivar Ouro Negro

“…In Brazil, 'AND 277', 'BAT 332', 'Cornell 49-242', 'MAR-2', and 'Mexico 54' are important ALS resistance sources (Balbi et al, 2009;Nietsche, et al, 2001;Sartorato & Alzate-Marin, 2004;Silva et al, 2008). The resistance present in these genotypes in crosses with susceptible cultivar Rudá was shown to be monogenic and dominant (Caixeta et al, 2003;Carvalho et al, 1998;Ferreira et al, 2000;Nietsche et al, 2000;Sartorato et al, 2000).…”

“…These conditions, combined with the use of susceptible cultivars, favor the occurrence of the disease, leading to losses that may reach over 80% of the production. The high pathogenic variability of P. griseola is an obstacle for the development of resistant cultivars Sartorato, 2006;Sartorato & Alzate-Marin, 2004;Silva, Souza, Sartorato, & Freire, 2008).…”