Genetic variations of ectomycorrhizal fungi: extramatrical phase of Pisolithus sp.

Abstract

LAMHAMEDI, M. S., and FOKTIN, J. A. 1991. Genetic variations of ectomycorrhizal fungi: extramatrical phase of Pisolirhus sp. Can. J . Bot. 69: 1927Bot. 69: -1934. The ability of 28 monokaryons and 78 reconstituted dikaryons of Pisolirhus sp. from South Africa to form rnycelial strands in association with Pinus pinusrer was tested under aseptic and non-aseptic conditions. All monokaryotic and some dikaryotic cultures failed to form mycelial strands either on agar medium or in growth pouches. The remaining dikaryotic cultures showed wide genetic variation in the development of mycelial strands and in the extension of their extrarnatrical phase. The exploration of the surrounding environment by the extramatrical phase from synthesized Pirzus pirzuster -dikaryotic cultures of the Pisolittzl~s sp. depended largely upon the type of medium used, being more extensive in soil than on nutrient agar medium. Microscopic observation showed that mycelial strands were formed by aggregations of hyphae. Large central hyphae with disorganized cytoplasm were observed in some strands. The results are discussed in relation to nutrient and water absorption.Key \vords: Pisolitlzus sp., Pirzus pi~zaster, genetic, extramatrical phase, mycelial strands. LAMHAMEDI, M. S., et FORTIN, J . A. 1991. Genetic variations of ectomycorrhizal fungi: extramatrical phase of Pisolitlzus sp. Can. J. Bot. 69 : 1927-1934. La capacite de 28 monocaryons et de 78 dicaryons provenant d'Afrique du Sud de former des cordons rnycCliens a Ct C testCe sous des conditions steriles et non stkriles. Tous les monokaryons et certains dikaryons n'ont pas form6 des cordons myceliens en milieu gtlosC et en sachet de croissance. Le reste des cultures dikaryotiques ont montrC une large variabilitk g6nCtique quant au developpement des cordons myckliens et i I'extension de la phase extramatricielle. L'exploration de la phase extrarnatricielle, issue de I'association symbiotique Pirzus pirzusrer-dikaryons de Pisolirhus sp. depend du milieu environnant et a Ctd plus extensive sur le sol que sur le milieu nutritif gdosk. Les observations microscopiques ont lnontre que les cordons mycCliens sont formes par des aggregations d'hyphes. Les cytoplasmes dCsorganisCs ont CtC observes chez les larges hyphcs centraux. Les resultats sont discutCs en relation avec I'absorption de I'eau et des ClCrnents nutritifs.

Genetics of ectomycorrhizal symbiosis

“…has recently been studied by Lamhamedi et ai. (1990) and by Lamhamedi & Fortin (1991). However, there is little information concerning the proportion of the genetic variability that is related to the additive and non-additive genetic component.…”

“…Inoculation with parental monokaryons was not carried out because monokaryotic Pisolithus sp. do not produce mycelial strands (Lamhamedi & Fortin, 1991) and do not form as many ectomycorrhizas as dikaryotic cultures (Lamhamedi et al, 1990).…”

“…After four weeks, seedlings of similar size were selected and transferred to large Petri dishes (150 x 15 mm) containing 150 ml of autoclaved sand/peat substrate (4: 1 v/v) moistened with 35 ml of sterile mineral solution (Lamhamedi & Fortin, 1991) for ectomycorrhiza synthesis. Each Petri dish received one seedling and the root system was sandwiched between two 9·5 cm square nylon sheets (150 flm mesh) (Wong & Fortin, 1989).…”

“…genotypes utilized as inoculum. Intraspecific variation in this fungus also occurs in the production of mycelial strands (Lamhamedi & Fortin, 1991) and rate of ectomycorrhiza formation (Molina, 1979;Marx, 1981 ;Dixon, Garret & Stelzer, 1987;Lamhamedi et al, 1990).…”

Growth of young argan tree seedlings ( Argania spinosa L. Skeels) in north - east of morocco under controlled conditions at different NaCl concentrations

“…In contrast, the growth in terms of height and diameter were strongly affected by salt. According to the standards reported by [30], the height to diameter ratio expressed in cm/mm should be lower than 8. This quotient (H/D ratio) calculated in case of all applied treatments exceed this threshold, which means that salt stress has no effect on this quotient.…”