Abdullah, F.

Universiti Putra Malaysia Institutional Repository

UPM Research Report 1998: Volume 2BIODIVERSITY OF MACROFUNGI OF MANGO(MANGIFERA SP.) AND THEIR PATHOGENICIMPORTANCEF. AbdullahFaculty of Science and Environmental StudiesUniversiti Putra Malaysia, 43400 UPM, Serdang, Selangor,MalaysiaKeywords: macrofungi, mango, pathogenicity, gano-derma, monokaryon.IntroductionFreshly cut stumps of mangoes (Mangifera indica) were con-sistently observed to harbour non-laccate Ganoderma sporo-phores. In our case study, about 10% of the trees in an or-chard had to be felled because of an unidentified disease,which resulted in rapid defoliation of the tree. Non-laccateGanoderma sporophores were observed on the stumps within2 months. This study investigated the biological species ofGanoderma from mangoes by cross-matching of monokary-ons, examines the genetic relationships of Ganoderma frommango stumps obtained from 3 regions of the country andcarries out an in vivo pathogenicity test on mango seedlings.Materials and MethodsMorphological studies of the sporophores and spores weremade of specimens derived by artificial sporophore induction(Abdullah, 1996) on rubber wood blocks, using mycelia iso-lated from the fruiting body collected from the study sites.Data on biological speciation were obtained from singlespore cultures ('monokaryons') of Ganoderma from whichone set of tester consisting of 4 single spore isolates ofGanoderma were then cross-matched with monokaryons ofG. australe and G. applanatum from United Kingdom andNew Zealand to test for biological speciation. For isozymeelectrophoresis, isolates made from Ganoderma sporophorescollected from various mango stumps in Sri Manjung(Perak), Sri Serdang (Selangor) and Petaling Jaya (Selangor)were scored for banding patterns. The patterns were thentransformed as input data for a UPGMA cluster analysisbased on Roger's Distance measure (Rohlf, 1990), version1.8, which eventually generates a dendrogram. For pathoge-nicity studies, isolates of Ganoderma from the 3 study sites236were used to artificially infect bud-grafted mango seedlings,following the method of Khairuddin et al. (1991) with modi-fications.Results and DiscussionMorphological studies showed that the fruiting bodies fromthe 3 study sites were not significantly different in shape,colour and thickness of pileus and spore sizes. Cross match-ing of monokaryons showed the species on mango was G.australe and not G. applanatum. Isozyme studies showedthat their banding patterns were similar for all mango isolatesand to Ganoderma isolated from rubber and cocoa hosts butdifferent from Ganoderma on oil palms and coconuts. Patho-genicity studies showed that Ganoderma isolates collectedfrom mango stumps showed a relatively low level of diseasesusceptibility, where approximately 10% were infected in all3 separate trials. However, of the small number that was in-fected, all showed 100% mortality. The first visible symp-toms of infection was the appearance of white rhizomorph atthe basal stem end, which eventually formed Ganodermaprimodia, followed by collapse of the foliage. By the time theGanoderma sporophores were well formed 90% of the leaveshad dried up without turning yellow and had fallen, and themain tap root swelled and rotted.ConclusionsThe non-laccate Ganoderma on mango from the 3 study siteswere confirmed as G. australe. They caused a relatively lowrate of infection at 10% when artificially infected, and is per-haps lower in a natural situation. However, of those that wereinfected, 100% of the mango seedlings died by the time thesporophores emerged, thus the presence of this fungus infruit orchards may prove a serious threat to the fruit trees.ReferencesAbdullah, F. 1996. Basidiomata induction and characterisation ofGanoderma from oil palm (Elaeis guineensis) on three agrowastesubstrates. Pertanika J. Trop. Agric. Sci. 19(213):117-122.Khairuddin, H., Lim, T.K. and Abdul Rahman, A.R. 1991. Pathoge-nicity of Ganoderma boninense Pat. on oil palm seedlings. Proc.PORIM Int. Palm Oil Conf: Progress, Prospects and ChallengesTowards the 21st Century, 9-14 Sept. 1991, Kuala Lumpur.Rohlf, F.I. 1990. NTSYS-pc, Numerical Taxonomy and multivariatesystem, version 1.B. Exeter Publishing Ltd.: Setauket, New York,USA.Supported by IRPA Grant 09-02..()4~0008

Biodiversity of macrofungi of mango (Mangifera sp.) and their pathogenic importance

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Biodiversity of macrofungi of mango (Mangifera sp.) and their pathogenic importance

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