Journal of the Rubber Research Institute of Sri Lanka

Permanent URI for this collectionhttps://dl.nsf.gov.lk/handle/1/8676

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Author: search.filters.author.Wijesundera, R.L.C.Subject: search.filters.subject.Hevea brasiliensis

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    Susceptibility of different leaf stages of Hevea to Corynespora cassiicola
    (Rubber Research Institute. Agalawatta, 2010) Fernando, T.H.P.S.; Jayasinghe, C.K.; Wijesundera, R.L.C.; Siriwardena, D.
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    Laboratory tests to assay responses of rubber (Hevea brasiliensis)genotypes to Phytophthora meadii
    (Rubber Research Institute. Agalawatta, 2009) Jayasuriya, K.E.; Wijesundera, R.L.C.
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    Variability in defence responses of rubber genotypes against Phytophthora meadii infections
    (Rubber Research Institute. Agalawatta, 2005) Jayasuriya, K.E.; Wijesundera, R.L.C.
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    The biotic effect of the surface microflora on phytophthora meadii infection of rubber petioles
    (Rubber Research Institute . Agalawatta, 2002) Jayasinghe, K.E.; Wijesundera, R.L.C.; Thennakoon, B.I.; Silva, N.
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    Toxic metabolite from clove isolate of Cylindrocladium quinqueseptatum
    (Rubber Research Institute. Agalawatta, 1999) Jayasinghe, C.K.; Wijesundera, R.L.C.
    Cylindrocladium Quinqueseptatum Boedijn Reitma causes seedling blight and extensive defoliation on a wide variety of plants and is widely distributed in the humid tropics.It is a serious pathogen of Eugenia caryophyllata in Sri lankaand has been identified as a potential lpathogen on Hevea brasileensis in the eastern Hemispher .All cloveisolates;IMI 342173 (rt),359378(Aw),359379(Rw)and 359380(Kp) of c.quinqueseptatum tested were found to be capable of secreting toxic substances to the growing medium.Toxic culture filtrates proved to be thermostagbl4e(up to 100C)and host specific.The type and the size of the lesions lproduced by the crude toxin of different isolates varied markedly.Isolate,Rt produced the largest lesions (Highest score) indicationg its aggressive nature in toxin production while Aw and Rw isolates showed a mild reaction.When the reaction of Hevea clones towards the crude toxin was considered three main clusters ofclones were distinguished through cluster analysis indicationg the marked variation of Hevea clones grown in the Eastern Hemisphere in their sensitivity to the crude toxin.The possibility of making use of this toxin as a tool in screening Hevea populations for cylindrocladium leaf spot disease has also been discussed.
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    Cell wall degrading enzyme secretion by Cylindrocladium quinqueseptatum
    (Rubber Research Institute. Agalawatta, 1999) Jayasinghe, C.K.; Wijesundera, R.L.C.
    Cylindrocladium quinqueseptatum causes leaf fall of clove in Sri Lanka and is responsible for the leaf spots of rubber in Malaysia.only one isolate (KP)from four pathogenic isolates examined secreted polygalacturanase(PG) when grown in liquid media.None ofthe isolates secreted pectin lyase(PL).The extracts of clove and rubber leaf tissues,inoculated with the KP isolate did not show any PG and PL activity .The leaf tissue did not have the ability to ingibit c.quinqueseptatum PG produced in culture.All isolates of C.quinquesepltatum secreted cellulases viz.cellobiase and b-glucosidase in culture.cellobiase was detected in the inoculated rubber leaves,The levels of B-glucosidase,an ingerent enzyme of Hevea leaves,also increased rapidly following infection.The results indicate that pectic enxymes play a minimal or no role in disease developmet of C.quinqueseptatum infecton in cloves and Hevea.Thus cellulolyic enzyme probably play a nutritive role.