The breeding biology of biotypes of the witches' broom pathogen of cocoa, Crinipellis perniciosa

Abstract

Investigation of the breeding biology of the agaric Crinipellis perniciosa (causal agent of witches' broom disease of cocoa in South America) found that two distinct breeding strategies exist among the four known biotypes of the fungus, which are specific to cocoa (C-biotype), solanaceous hosts (S-biotype), Bixa orellana (B-biotype) and liana vines (L-biotype). The homomictic (primary homothallic) behaviour of the C-biotype was confirmed and single basidiospore isolates (SSIs) of the S-biotype and B-biotype were found to behave in a similar manner. The mycelia of most SSIs of the L-biotype did not bear clamp connections and pairings between sibling SSIs established that an outcrossing mechanism under the control of two unlinked mating type factors was operating (i.e. bifactorial heterothallism). These matings also suggested that one of the mating factors has a twogene structure. The occurrence of bi-and trinucleate basidiospores and SSIs bearing true or false clamp connections suggests that the L-biotype exhibits a limited degree of secondary homothallism.

Genetic diversity of polysporic isolates of Moniliophthora perniciosa (Tricholomataceae)

“…The authors reported that this isolate was unable to complete its life cycle on B. orellana, and the isolate was later proven to be genetically identical to biotype C isolates found in Bahia (Bastos and Andebrhan, 1986;Griffith and Hedger, 1994a). Therefore, Meinhardt et al (2008) do not consider biotype B a distinct subgroup of this species.…”

“…This structural model was observed in the present study, with genetic variation among Solanaceae isolates from various regions of Minas Gerais, including S. lycocarpum (Viçosa), S. lycocarpum (Coimbra), and S. cernuum (Rio Pomba, Minas Gerais; see Figure 3). Griffith and Hedger (1994a) have suggested that biotype C did not exist before the T. cacao culture in the Amazon region and that the lower variability between their strains (compared with those of biotype L) found only in Amazonas State suggests that a recent origin and new selective forces caused by T. cacao monoculture have resulted in this evolution. These relationships were observed in SCG data of mitochondrial DNA polymorphism (Griffith and Hedger, 1994a,b).…”

“…The variability characterization of M. perniciosa has been based on morphologic and cultural characteristics, somatic compatibility (SCG), molecular analysis, and biochemistry relationships with Theobroma cocoa and other Theobroma spp (Hedger et al, 1987;McGeary and Wheeler, 1988;Wheeler and Mepsted, 1988;Griffith and Hedger, 1994a;Arruda et al, 2003;Lana et al, 2011). Anastomosis between mycelium from different origins might give rise to a heterokaryon appearance in the saprophytic mycelium, and variability subsequently increases in the next basidiospore generation.…”

Avaliação da variabilidade de biotipos de Moniliophthora perniciosa

“…Na primeira, chamada de fase biotrófica, o fungo apresenta hifa primária (micélio biotrófico), relativamente larga (5 a 20 µm), sem grampos de conexão, que cresce intercelularmente sem causar a morte do tecido, formando a chamada vassoura-verde. Após dois a três meses o micélio passa por uma fase de transição (dicariotização), passando para a fase necrotrófica/saprofítica, com hifa secundária (micélio saprofítico) mais fina (1,5 a 3,0 µm), hialina, dicariótica, com grampos de conexão, que coloniza o tecido da planta intra e intercelularmente causando necrose e morte de tecidos infectados distante do local original de infecção, formando assim a vassoura-seca (ALBUQUERQUE et al, 2005;CALLE;COOK;FERNANDO, 1982;BASTOS, 1979;FRIAS;SCHIMIDT, 1991;KILARU;HASENSTEIN, 2005;MEINHARDT et al, 2006;SCARPARI et al, 2005;SHAW;VANDENBON, 2007;MATSUOKA, 1999 GRAMACHO et al, 2007;HEDGER, 1994a;PLOETZ et al, 2005;SCHMIDT, 1996;RINCONES et al, 2006).…”

Mapas de ligação e identificação de Locos Controladores de Características Quantitativas (QTLs) associados à resistência a Crinipellis perniciosa em acessos de cacaueiro (Theobroma cacao) originários da Amazônia Brasileira

“…No Sul da Bahia, onde existia um maciço continuo de 600 mil hectares de cacaueiro plantados na forma de monocultura, a vassoura-de-bruxa atingiu rapidamente proporções epidêmicas após seu primeiro relato. Esta epidemia foi favorecida pelas características climáticas da região, onde as chuvas são bem distribuídas durante o ano, e pelo fato da principal variedade de cacaueiro plantada ser do tipo 'comum', que é altamente suscetível ao C. perniciosa (LUZ et al 1997 GRIFFITH;HEDGER, 1994). A classificação de isolados do biótipo-C foi inicialmente baseada em estudos de patogenicidade (HEDGER et al 1987;MEPSTED, 1988) em testes bioquímicos e de incompatibilidade somática de micélios saprofíticos (HEDGER et al, 1987;MCGEARY;GRIFFITH;HEDGER, 1994).…”