Growth stimulation of Woollsia pungens by a natural ericoid mycorrhizal fungal endophyte – Publication

Abstract of a publication based on research funded in part by the Australian Flora Foundation

J. H. Palmer, B. M. Horton, W. G. Allaway and A. E. Ashford
School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney,
NSW 2052, Australia.
Australasian Mycologist 26 (1): 1-8 (2007)

Woollsia pungens (Cav.) F. Muell. seedlings were germinated and grown under axenic conditions on either agar gel or Phytagel in closed transparent polystyrene culture boxes. Two months after sowing, when the seedlings were in the juvenile stage, culture boxes were inoculated with a fungal isolate MG60 which had previously been isolated from naturally-grown W. pungens. The inoculum and medium surfaces were then covered with a thin layer of autoclaved soil. After 5 months further growth in natural daylight the seedlings were harvested. Hair roots were fixed, stained, and scored for mycorrhizal colonisation by the presence of intracellular hyphae and fungal coils. Seedling growth was adversely affected by agar gel, with leaf yellowing and lack of mycorrhiza formation. Seedlings grown in non-inoculated Phytagel culture boxes appeared more vigorous than those reared on agar, although a reddish leaf pigment and some chlorosis were evident and measured growth was not statistically significantly different. All the sampled hair root systems of seedlings reared in inoculated Phytagel culture boxes scored positive for intracellular fungal hyphae or fungal coils characteristic of ericoid mycorrhizas. These structures were present in 55% of the hair roots examined from the inoculated culture boxes. The inoculated seedlings growing on Phytagel possessed tall shoots with normal leaf colour, and almost twice as many leaves at harvest as the non-inoculated Phytagel controls, indicating a positive effect of MG60 on seedling growth probably via nutrient uptake. This trial has demonstrated that Phytagel covered by natural soil is a suitable growing medium for W. pungens and that inoculation with the fungus MG60 results in the formation of ericoid mycorrhizas and has a beneficial effect on seedling growth.
Key words: Epacridaceae, Ericaceae, ericoid, hair root, Hymenoscyphus, mycorrhiza, Woollsia.