Morphological and molecular characterization of Colletotrichum capsici

AUTHOR: Kinlay Tshering

ABSTRACTS

The taxonomy and diversity of Colletotrichum capsici was validated by morphological characters (conidia shape & size, colony characteristics, appressoria size) and molecular analysis using ISSR (Intersimple sequence repeats) markers with the objectives to adopt ISSR technique to assess the level of genetic variation among C. capsici isolates, to determine if the genetic variation among isolates corresponded with variation in morphological traits, and to determine if differentiation among C. capsici isolates based on morphological or ISSR variation was related to the host from which the isolates were collected. Morphological characters were quite variable within the species. Molecular analysis revealed that there was a genetic diversity with Thai isolates from Capsicum annuum being more similar than the other isolates from Queensland collected from other hosts like sugar apple, soy bean, etc. The phylogenetic groupings of C. capsici based on ISSR polymorphism did not appear to be congruent with morphological pattern and the rate of growth of isolates in culture. Further molecular analysis with a larger samples from a range of countries are required to determine if the clustering based on geographic origin and host plant is occurring. A high degree of molecular variability indicated that ISSR markers can be well utilized for the intraspecific characterization of C. capsici.

KEYWORDS:

Colletotrichum capsici, ISSR, Morphology, Molecular variability, Capsicum annuum

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