Submitted to: Mycological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2006
Publication Date: 7/28/2006
Citation: Rincones, J., Mazotti, G.D., Griffith, G.W., Pomela, A.W., Figueira, A., Queiroz, M.V., Pereira, J.F., Azevedo, R.A., Pereira, G.A., Meinhardt, L.W. 2006. Genetic variability and chromosome-length polymorphisms of the witches’ broom pathogen crinipellis perniciosa from various plant hosts in south america. Mycological Research. 110:821-832. Interpretive Summary: Research into diseases of cacao is important to the USA economy because cacao is the raw material for the production of chocolate and the chocolate industry is one of the main consumers of dairy, nuts, oils and sugar products. Fungal diseases such as Witches’ Broom Disease (WBD) of cacao have devastated cacao production, in much of the Western Hemisphere. The present study looked at the genetic variability of this fungal pathogen that causes WBD with different molecular techniques and compared the results with other forms of this pathogen from different plants and regions of South America. New populations of this fungus were identified in the Amazon region of Brazil that are potential new threats to existing cacao breeding programs. This work is important for understanding fungal population dynamics and to predict future threats to this agricultural system. Breeders, plant pathologist, extension personnel and farmers will benefit directly from this information.
Technical Abstract: Crinipellis perniciosa has been classified into at least four known biotypes associated with members of unrelated plant families. In this study, genetic variability is shown for 27 C- (cacao), 4 S- (Solanum) and 7 L-biotype (Liana) isolates of C. perniciosa collected from different regions of Brazil and South America. The objective was to investigate the genetic variability of the pathogen in the cacao-producing region of Bahia, Brazil, and elsewhere, through microsatellite analysis and attempt to identify possible correlations between host-specificity and electrophoretic karyotypes. The PCR-banding patterns were found to vary both within and between the different biotypes, and a correlation was established between the PCR-banding patterns and the chromosomal-banding patterns of each isolate. Microsatellite and chromosomal patterns among all of the L- and S- biotype isolates were distinctly different from the C-biotypes analyzed. A higher degree of genetic and chromosomal variability was found among C-biotype isolates from the Amazon in comparison to C-biotype isolates from Bahia, which seems to be comprised of only two main genotypes. This finding has important implications to the current cacao-breeding program in Brazil.