Browsing by Author "Theertha Prasad, D."

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    Genetic diversity in Hirsutella thompsonii isolates based on random amplified polymorphic DNA analysis
    (2007) Aghajanzadeh, S.; Theertha Prasad, D.; Mallik, B.
    Hirsutella thompsonii Fisher is a host-specific fungal pathogen of the diverse group of arthropods known as the Acari. It particularly affects eriophyid mites, and the identification of its isolates is a difficult task due to its pleomorphic nature. Seven isolates of H. thompsonii var. thompsonii and H. thompsonii var. synnematosa collected from various agro-climatic regions of India were subjected to PCR analysis using random decamer primers to differentiate between them. Random amplified polymorphic DNA analysis revealed that all of the isolates from the citrus rust mite, Phyllocoptruta oleivora Ashmead (Acari: Eriophyidae), clustered together, with the exception of one, HtCRMB. The only isolate of H. thompsonii from Aceria guerreronis keifer (Acari: Eriophydae), HtPDBC, clustered separately.
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    Identification of molecular markers associated with mite resistance in coconut (Cocos nucifera L.)
    (2007) Shalini, K.V.; Manjunatha, S.; Lebrun, P.; Berger, A.; Baudouin, L.; Pirany, N.; Ranganath, R.M.; Theertha Prasad, D.
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    Identification of molecular markers associated with mite resistance in coconut (Cocos nucifera L.)
    (2007) Shalini, K.V.; Manjunatha, S.; Lebrun, P.; Berger, A.; Baudouin, L.; Ranganath, R.M.; Pirany, N.; Theertha Prasad, D.
    Coconut mite (Aceria guerreronis‘Keifer’) has become a major threat to Indian coconut (Coc¸cos nuciferaL.) cultivators and the processing industry. Chemical and biological control measures have proved to be costly, ineffective, and ecologically undesirable. Planting mite-resistant coconut cultivars is the most effective method of preventing yield loss and should form a major component of any integrated pest management stratagem. Coconut genotypes, and mite-resistant and -susceptible accessions were collected from different parts of South India. Thirty-two simple sequence repeat (SSR) and 7 RAPD primers were used for molecular analyses. In single-marker analysis, 9 SSR and 4 RAPD markers associated with mite resistance were identified. In stepwise multiple regression analysis of SSRs, a combination of 6 markers showed 100% association with mite infestation. Stepwise multiple regression analysis for RAPD data revealed that a combination of 3 markers accounted for 83.86% of mite resistance in the selected materials. Combined stepwise multiple regression analysis of RAPD and SSR data showed that a combination of 5 markers explained 100% of the association with mite resistance in coconut. Markers associated with mite resistance are important in coconut breeding programs and will facilitate the selection of mite-resistant plants at an early stage as well as mother plants for breeding programs.