|MAHALINGAM, THIREGA - University Of Kelaniya|
|RJAPAKSE, CHANDIMA - University Of Kelaniya|
|SOMACHANDRA, K - Department Of Agriculture Government Of Sri Lanka|
|ATTANAYAKE, RENUKA - University Of Kelaniya|
Submitted to: Pathogens
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2020
Publication Date: 4/22/2020
Citation: Mahalingam, T., Chen, W., Rjapakse, C.S., Somachandra, K.P., Attanayake, R. 2020. Genetic diversity and recombination in the plant pathogen Sclerotinia sclerotiorum detected in Sri Lanka. Pathogens. 9(4):306. https://doi.org/10.3390/pathogens9040306.
Interpretive Summary: Sclerotinia sclerotiorum is an especially destructive fungal pathogen of several hundred economically important crops worldwide. Even though population structure and genetic diversity of S. sclerotiorum from temperate environments has been well studied, only a few studies have been conducted in tropical environments. Consequently, less is known about S. sclerotiorum populations in the tropics. The objective of this study was to examine genetic diversity in a population of S. sclerotiourm collected from a tripical environment. A total of 47 isolates were collected from commercial cabbage fields in the Nuwara Eliya district of Sri Lanka. Each isolate was examined with DNA markers and also for their ability to grow with other isolates. Our results demonstrated that a single plant could be infected by several genetically distinct isolates of the pathogen and there was a relatively high degree of genetic variation present in the population. Understanding the amount of genetic variation present in populations of this globally destructive plant pathogen can assist in the development of safe, economical, and effective methods for controlling plant diseases.
Technical Abstract: Sclerotinia sclerotiorum is an important fungal pathogen of many economically important crops worldwide. Even though population structure and genetic diversity of S. sclerotiorum from temperate environments has been well studied, only a few studies have been conducted in tropical environments. To address this lack of understanding, 47 isolates of S. sclerotiorum were collected from commercial cabbage fields in the Nuwara Eliya district of Sri Lanka where the disease has been previously reported. All isolates were examined using Mycelial Compatibility Groupings (MCG) and Simple Sequence Repeat (SSR) markers. Fourteen MCGs and 23 SSR haplotypes were recorded with 0.56 mean expected heterozygosity (HE). Multilocus haplotypes were slighly correlated with MCGs. Population genetic structure analysis and principal coordinates identified three genetic clusters. Recombination was detected within each genetic cluster when isolates were subjected to clone correction. There was evidence of multiple infections in single plants based on the presence of more than one MCG on individual plants. However, multiple infections did not increase disease severity in detached leaf assays. We found high genetic diversity and recombination present in a S. sclerotiorum population from a tropical country, Sri Lanka. The importance of detecting genetic structure when inferring recombination is also highlighted.