Genetic diversity of Ganoderma in oil palm plantings

Abstract

Isolates of Ganoderma spp. associated with basal stem rot of oil palm were obtained by sampling from two palm plantings in Malaysia. Members of a subset of these were compared using a combination of somatic incompatibility and molecular genetic analyses. Incompatibility interactions between heterokaryons in culture indicated that Ganoderma generally occurred as numerous distinct strains, with compatible strains usually confined to individual palms. Analysis of restriction fragment length polymorphisms (RFLPs) in presumptive mitochondrial DNA (mtDNA) revealed heterogeneity among isolates from neighbouring palms, and from within individual palms. The combination of mtDNA variability and somatic incompatibility suggests that Ganoderma BSR does not spread by direct root-toroot contact between palms. The results may indicate infection spread through basidiospore dispersal or through contact with a heterogeneous long-term residual inoculum in debris.

Characterization ofArmillariaisolates from tea (Camellia sinensis) in Kenya

“…Abomo-Ndongo and reported dubious reactions for isolates K10 and K12. A similar phenomenon has been observed on other Basidiomycetes such as Ganoderma in oil palms where most isolates, even when taken from the same plant, were somatically incompatible with one another (Miller et al 1999). Group II seems to be an exception among Armillaria species, with the occur-rence of the dark demarcation line in intra-group pairings.…”

About Ganoderma boninense in oil palm plantations of Sumatra and peninsular Malaysia: Ancient population expansion, extensive gene flow and large scale dispersion ability

“…This result may reflect the fact that date of planting has no impact on the selection of specific fungal genotypes. It could also suggest that the inoculum present in the soil remains from one generation to another, highlighted by many authors (Hasan and Turner 1998;Breton et al 2006;Rees et al 2009), is either not a major source of disease or has already a very high diversity level as suggested by Miller et al (1999). This absence of correlation between factors and selection of specific genotypes could thus be caused by an overall very high level of genetic diversity both present in airborne basidiospores and dead palm trunk and stumps dwelling inoculum.…”

“…Unlike the oil palm, which was introduced into Southeast Asia in the early 20th century (Jacquemard 2011), the coconut palm has been historically present in the region (Gunn et al 2011) and it is to be noted that coconut precede oil palm on many fields in Malaysia and Sumatra. Several authors have cited the coconut tree as a possible source and/or reservoir of G. boninense inoculum in Southeast Asia (Turner 1965a;How & Nawawi 1985;Miller et al 1999;Pilotti et al 2004). Basal stem rot disease on oil palm was first described in 1931, in Malaysian plantations, by Thompson (Ariffin et al 2000); it can now be found sporadically in all oil palm plantation areas in Southeast Asia.…”

“…Since then, much effort has been devoted to studying the oil palm's defense mechanisms against G. boninense infection and to developing BSR resistant or tolerant varieties (Idris et al 2004;Durand-Gasselin et al 2005;Tee et al 2013;Ho & Tan 2014). While some studies have attempted to improve understanding of the biology and diversity of G. boninense by describing its morphology in detail (How & Nawawi 1985), characterizing its modes of sexual reproduction (Pilotti et al 2002) and quantifying its genetic diversity with molecular markers (Miller et al 1999) or mating type systems studies (Pilotti et al 2003), its genetic diversity and population structure across oil palm plantations in Southeast Asia are still poorly understood.…”

In vitro growth of Ganoderma boninense isolates on novel palm extract medium and virulence on oil palm (Elaeis guineensis) seedlings

“…Genetic variations among different Ganoderma isolates obtained from within same or between palms and within same or different plantations were found to be relatively high with various molecular apporaches, such as mitochondrial DNA restriction fragment length polymorphisms (RFLPs), random amplified polymorphic DNA (RAPD) and Random Amplified Microsatellite (RAMS) (Miller et al, 1999;Latiffah et al, 2005;Rees et al, 2012). Furthermore, heterogeneity in genetic backgrounds among G. boninense isolates from infected oil palms was also demonstrated through mating test with monokaryotic cultures and somatic compatibility test (Pilotti et al, 2003;Rees et al, 2012).…”