Introduction

The coffee leaf rust disease (CLR), caused by the obligate parasitic fungus Hemileia vastatrix,has been the most economically important disease affecting coffee for over a century (Talhinha et al. 2018). Although, the last major outbreak of the disease was in 2012, the coffee leaf rust disease is still a significant challenge to coffee production in Jamaica. Recently, local coffee growers have expressed concerns that new genotypes of the fungus have hindered their efforts to control the disease. To investigate these concerns, the study aimed to assess clonality among isolates of the Hemileia vastatrix collected during two production cycles over the wet and dry seasons of Jamaica.

Method:

• In 2018, DNA was extracted from rust infected coffee leaves collected from 75 trees on 16 farms throughout the coffee growing areas in Jamaica that had been previously sampled in 2016.
• Genetic diversity was assessed using the same 11 polymorphic microsatellite markers and procedures that amplified the samples from the 2016 study.

Results

From the 11 markers, only 3 amplified consistently across 11 different genomic locations. The poor marker amplification was mainly due to low levels of DNA. During the sample collection, very high levels of hyperparasitism by Verticillium sp., was observed in the field. This observation is significant as Verticillium sp. attacks uredinospores of Hemileia vastatrix and therefore can severely reduce the amount of DNA available for amplification.

Conclusion

These results indicate that the dry season, may not be the most suitable time to collect uredinospores of H. vastatrix for molecular analyses due to the high prevalence of Verticillium sp.