Volume 6, Issue 1, February Issue - 2018, Pages:124-130
|Authors: Prathibha Veerappa Hanumanthappa*, Nanda Chinnaswamy, Mohan Rao Annabathula, Ramesh SampangiramaReddy, Nagaraja Niduvalli Ramachandrappa|
|Abstract: A total of sixty Colletotrichum isolates were purified from anthracnose disease samples, collected from 15 chilli growing districts of Karnataka. The isolates were evaluated for their morphological and genetic characterization using AFLP marker assay. Based on the morphological characterization, 40 isolates were identified as Colletotrichum capsici/truncatum and 20 as C. gloeosporioides. Considerable morphological variability was observed in C. gloeosporioides isolates compared to C. capsici isolates. AFLP marker assay could clearly differentiate the C. capsici and C. gloeosporioides isolates at 43% genetic similarity, thus complementing species classification based on morphological characterization. However, morphological and AFLP grouping of isolates indicates no clear correlation between clustering in the dendrogram and morphological grouping of C. capsici and C. gloeosporioides isolates this suggested existence of wide variability in both the species.|
|Full Text: 1 Introduction Chilli (Capsicum annuum L.) is an important vegetable cum cash crop of Indian subcontinent. The crop is grown largely for its pungent fruits, which are used both green and ripe to impart pungency to the food. The sustainability in chilli production is threatened by many biotic stresses such as several insect pests and diseases (Isaac,1992). Among these, anthracnose disease caused by Colletotrichum species is a major constraint to chilli production in major chilli-growing regions of the world and often results in high yield losses (Than et al., 2008). This disease caused by a complex of Colletotrichum species, results in both pre and post-harvest fruit decay (Liu et al., 2016).The species of Colletotrichum associated with anthracnose disease includes Colletotrichum capsici, C. gloeosporioides, C. truncatum, C. dematium, C. acutatum, C. siamense, C. fructicola (Hong & Hwang, 1998; Gopinath et al., 2006; Sharma & Shenoy 2014), C. coccodes and C. karstii (Saini et al., 2016). Colletotrichum infecting diverse hosts including cereals, legumes, vegetables, perennial crops and tree fruits have a high degree of pathogenic variability. Thus the accurate identification of the pathogen and species differentiation is imperative in development of appropriate management practices. Also studies on the variability of the pathogen populations are needed to direct breeding efforts towards long term resistance to anthracnose disease. Classically, identification and characterization of Colletotrichum spp. was primarily relied on morphological characters such as colony color and growth rate, shape and size of conidia, optimal temperature for growth, presence or absence of setae and existence of the teleomorph (Adaskaveg & Hartin, 1997; Freeman et al., 1998). Although these criteria are valuable but alone are not always adequate for reliable differentiation among Colletotrichum spp. due to variation in morphology and phenotype among species under environmental influences (Cannon et al., 2000). To overcome the inadequacies of these traditional schemes, molecular techniques combined with morphological studies have proven to be effective for characterization of Colletotrichum species (Sreenivasaprasad & Talhinhas, 2005; Van Hemelrijck et al., 2010). Therefore the present investigation was carried out to assess the variability in Colletotrichum spp. infecting chilli in Karnataka state of India using morphometric and molecular approaches 2 Materials and Methods 2.1 Collection and isolation of Colletotrichum spp. |
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