Electrophoretic karyotype analysis of Crinipellis perniciosa, the causal agent of witches' broom disease of Theobroma cacao.
ABSTRACT Pulse-field gel electrophoresis (PFGE) was used to determine the genome size and characterize karyotypic differences in isolates of the cacao biotype of Crinipellis perniciosa (C-biotype). The karyotype analysis of four isolates from Brazil revealed that this biotype could be divided into two genotypes: one presenting six chromosomal bands and the other presenting eight. The size of the chromosomes ranged from 2.7 to 5.3 Mb. The different genotypes correlate with telomere-based PCR analysis. The isolates with six chromosomal bands had two that appeared to be doublets, as shown by densitometric analysis, indicating that the haploid chromosome number for this biotype is eight. The size of the haploid genomes was estimated at approximately 30 Mb by both PFGE and Feulgen-image analysis. DNA hybridization revealed that the rDNA sequences are clustered on a single chromosome and these sequences were located on different chromosomes in an isolate dependent manner. This is the first report of genome size and chromosomal polymorphism for the C-biotype of C. perniciosa.
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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 two-gene 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.Heredity 01/1994; 72(3):278-289. · 4.11 Impact Factor
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ABSTRACT: Basidiospores of Crinipellis perniciosa (Stahel) Singer germinated rapidly in water and on standard agar media to produce a fine, hyaline, binucleate mycelium 1.5-3 μm diam, with clamp-connexions; the secondary or dikaryotic mycelium. White to cream, fast-growing, regular, cotton-like colonies were formed on agar. The primary mycelium was short-lived and dikaryotization occurred within 24–48 h. Basidiospores on vigorous cocoa callus tissues germinated slowly with short, abnormally swollen germ-tubes giving rise either to thickwalled chlamydospores or to a grossly swollen flexuous, hyaline to brown, uninucleate mycelium 5–20 μm diam with dense granular cytoplasm. Characteristic slow-growing, cerebriform colonies were irregularly formed on agar surrounding the callus. A similar, although less swollen, mycelium was observed intercellularly in infected green cocoa stems (brooms) and pods. Dikaryotization occurred when active callus or plant growth declined, and in old callus cultures and dead brooms the tissues were colonized, both inter- and intracellularly, by secondary mycelium. The primary mycelium became thick-walled and devoid of contents. The life cycle of C. perniciosa is divided into two phases which are separated morphologically, genetically and physiologically: the biotrophic or parasitic, monokaryotic phase and the necrotrophic or saprophytic, dikaryotic phase. The fungus is now classified as a hemibiotroph.Transactions of the British Mycological Society 01/1980; 74(3):515-523.
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ABSTRACT: Crinipellis perniciosa (Stahel) Singer is the causal agent of witches' broom disease in the Sterculiaceae, Solanaceae, and Bixaceae families. The disease is endemic to the Brazilian Amazon, and was first reported infecting Theobroma cacao (cocoa) in the State of Bahia, Brazil, in 1989. Random amplified polymorphic DNA (RAPD) analyses were performed on 46 isolates of C. perniciosa from cocoa that were collected from 15 counties in Bahia and the Brazilian Amazon. A total of 258 RAPD loci from 20 primers and three mixed primers were analyzed. Of these loci, 108 (42%) were polymorphic, with an average of 4.7 polymorphic loci per primer produced. Genetic similarities were estimated using Nei and Li's index and UPGMA clustering. Bootstrap analysis divided the phenogram into four significantly different clusters: two groups contained isolates from Ariquemes and from Ouro Preto, Rondnia, and the other two separated the isolates from Bahia into two major groups of C. perniciosa, classified as Group 1 (G1) and Group 2 (G2). The two groups of isolates from Bahia differed for their genetic similarity with the isolates from the Brazilian Amazon. The geographic distribution of the groups in Bahia suggests two independent focal points of introduction. Ongoing programs to screen for resistant cocoa genotypes should consider both groups of isolates.European Journal of Plant Pathology 01/1999; 105(2):167-175. · 1.61 Impact Factor