Discrimination of some African Armillaria species by isozyme electrophoretic analysis

Abstract

SUMMARYTen Armillaria isolates, collected from various host plants and widespread geographical origins in tropical Africa, were cultivated on orange fragments in the presence of water and two different culture media in order to optimize enzyme and mycelial cord production. Seven enzymes involved in the primary metabolism of nitrogen and carbon (glutamate dehydrogenases, aspartate aminotransferase, malate dehydrogenase, glucose 6-phosphate dehydrogenase, 6-phospbogluconatt dehydrogenase and isocitrate dehydrogenase) were extracted from the mycelial cords and analyzed by polyacrylamide gel electrophoresis. Cluster analy.sis based on calculated similarity i-alues derived from isozyme banding patterns separated the isolates into fi\'e groups. Two isolates considered as belonging to A. metlea ssp. africana (an African species closely related to European A. metlea) were present in a clearly separated cluster when compared to the other isolate groups. Two Kenyan isolates, belonging to an as yet unnamed biological species, which w ere characterized by the production of few slow growing mycelial cords, were also found in a separate cluster with slightly greater similarit\' coefficients to the other isolates. The six other isolates, referred to as isolates of A. heimii (a highly variable species with different sexual systems) fell into three sub^clusters of variable homology. The two bomothallic heimii isolates from Tanzania and Malawi, which were \ery closely related, displaying 100 "" isozyme similarity, exhibited a higher degree of similarit>' with the two other homothalhc heimii isolates from Zimbabwe and Congo, than with the two heterothailic unifactorial heimti isolates from Cameroon and Gabon. The value of isozymes in the classification of African Armtllaria spp. is discussed.

Species delimitation in the African Armillaria complex by analysis of the ribosomal DNA spacers.

“…Mycelial cords were grown from an inoculated segment of orange supported above a column of Pachlewski's liquid medium in test tubes, as described by Agustian et al, 1994. They were collected 3 weeks after inoculation of the orange fragments, washed with distilled water and lyophilized.…”

“…The 11 African isolates chosen in this study have been extensively characterized previously by morphological criteria and total protein electrophoresis , and for 10 of them, by isozyme analysis (Agustian et al, 1994). Consequently, their phylogenetic relation- …”

“…Taxonomical studies of African Armillaria have included a wide range of investigation techniques such as observations of cultural characteristics (vegetative mat morphology, production of subterranean rhizomorphs, morphology of fruit bodies, and monospore isolates obtained in vitro) and pairing tests based on both sexual and somatic incompatibility Mohammed and Guillaumin, 1993;Mohammed et al, 1989). Other techniques such as the electrophoresis of isoenzymes (Agustian et al, 1994) and RAPD analyses have also been explored for differentiating the African species of Armillaria.…”

Characterization ofArmillariaisolates from tea (Camellia sinensis) in Kenya

“…Somatic incompatibility has been used to distinguish isolates of African Armillaria (Abomo-Ndongo and Guillaumin 1997). However, most attempts to characterize these have tended to employ methods that do not depend on the presence of basidiomata or haploid forms; e.g., techniques based on the use of isozyme electrophoresis (Mwangi et al 1989, Agustian et al 1994, Mwenje and Ride 1996, molecular markers such as DNA restriction fragment polymorphisms (Anderson et al 1987, Smith andAnderson 1989), RAPD (Mohammed 1994), nuclear DNA-DNA homology ( Jahnke et al 1987), and DNA sequence analysis (Anderson and Stasovski 1992). Analysis of the ribosomal DNA spacers, ITS and IGS, from Armillaria isolates collected from various geographical areas in tropical Africa discriminated A. mellea, A. heimii and a possible new species (Chillalli et al 1997).…”

Isozyme analysis of LE(BIN) Collection Flammulina strains

“…Isozyme analysis is rather efficient for determining variation in fungi (Micales et al 1986, Bonde et al 1993 and it has been widely used in the identification of species and isolates of a large number of Homobasidiomyceteous genera including Heterobasidion (Stenlid 1985), Pleurotus (Magae et a!. 1990;Zervakis & Labarere 1992), Lentinus (Ohmasa & Furukawa 1986), Armillaria (Wahlstrom et al 1991;Agustian et al 1994) and Clavicorona (Wu et al 1995).…”