Ian R. Hall ... (Hall, Buchanan, Wang & Cole 1998; Hall, Lyon, Wang & Sinclair 1988; Hall & ... an altitude of about 280 m (Wang, Hall, Sinclair & Cole 1995).
Boletus edulis in New Zealand Wang Yun New Zealand Institute for Crop & Food Research Limited Invermay Agricultural Centre Private Bag 50034, Mosgiel, NEW ZEALAND Alessandra Zambonelli Dipartimento di Protezione e Valorizzazione Agroalimentare University of Bologna, ITALY and Ian R. Hall New Zealand Institute for Crop & Food Research Limited Invermay Agricultural Centre Private Bag 50034, Mosgiel, NEW ZEALAND
Background Boletus edulis sensu stricto, B. aereus, B. aestivalis, B. pinophilus and B. reticulatus are a group of allied ectomycorrhizal fungi with edible fruiting bodies that are often grouped together as B. edulis sensu lato. Because it takes a specialist to distinguish between these species they are often marketed together using common names including cep and penny bun mushroom (English), cèpe de Bordeaux (French), Steinpilz (German), porcino (Italian), zhutui mo (pig leg mushroom, North China) and dajiao gu (fat feet mushroom, South China). Despite a world market of 20,000 to 100,000 t and considerable applied research in Europe centred around infecting hosts, cultivation of this group of mushrooms has remained elusive (Hall, Buchanan, Wang & Cole 1998; Hall, Lyon, Wang & Sinclair 1988; Hall & Wang 1998). B. edulis is found from the north of Scandinavia to the south of Italy and Morocco, and throughout Asia and North America including Mexico and in a wide range of habitats (Arora 1986; Breitenbach & Kränzlin 1991; Phillips 1981; Zang & Bi 1991). For example, in California B. edulis is found in coastal forests, dry interior oak forests and savannas and interior high montane forests of mixed conifers and hardwoods. Although it does not occur naturally in the Southern Hemisphere it has been accidentally introduced into South Africa (Van der Westhuizen 1983) where it has been reported to occur at the Cape of Good Hope (Pearson 1950) and the Southern Natal Midlands (J.M. Theron pers. comm.; Marais & Kotzé 1977).
New Zealand research B. edulis sensu lato was recorded for the first time in New Zealand in 1993 (Wang, Hall, Sinclair & Cole 1995) where it is found associated with Betula pendula, Fagus sylvatica, Prunus yedoensis, Quercus palustris, Q. robur, Q. cerris and Ulmus pumila. In New Zealand B. edulis fruits between early February and May and is always found associated with
Amanita cf. excelsa, A. muscaria, Xerocomus porosporus or Coenococcum spp. It is found primarily in an area about 80 km2 around the city of Christchurch (43S) from sea level to an altitude of about 280 m (Wang, Hall, Sinclair & Cole 1995). In April 1994 a poor specimen of B. edulis was found under a 15-year-old B. pendula at Lake Pukaki, about 270 km to the south of Christchurch. The distribution of B. edulis in Christchurch and the ages of trees on which it has been found suggests that it was introduced more than 100 years ago on the roots of a tree imported into New Zealand by an early European settler. It then became established in two large parks (Hagley and Victoria Parks) and at a Ministry of Works nursery. From these areas it then spread to many parts of Christchurch City on the roots of young, transplanted trees. The nursery supplied plants for stabilisation work around hydroelectric lakes in the centre of the South Island. This may well explain how the fungus spread to Lake Pukaki. More than 100 cultures were prepared from fruiting bodies collected in New Zealand as well as Austria, Italy, the UK and the USA. A universal feature of the isolates was their very slow growth on nutrient agar. Initial rates of growth were very slow but eventually the fastest isolates grew at an average rate of 10 mm per month. Some of the isolates made from caps or the upper parts of stalks of young fruiting bodies produced primordia on agar plates. This ability to produce primordia was gradually lost after several subculturings. Primordia were not formed by cultures prepared from old fruiting bodies. One possible explanation is that a gene system is switched on during the fruiting process and switched off as a fruiting body matures or cultures age. Pinus radiata and B. pendula were inoculated with these cultures using a wide variety of media. So far 4 cultures have formed mycorrhizal associations with both hosts. Pinus mycorrhizas were either monopodial or dichotomously branched and swollen. To begin with they were pure white and had many projecting randomly arranged hyphae. Eventually the projecting hyphae disappeared, the surface became off-white and velvety and had prominent cystidia. With time the mycorrhizas became darker, light to yellowish-brown, smooth and the outermost layers of the mantle peeled away. At this stage the cystidia were less obvious than at the velvety stage. Betula mycorrhizas were were fragile monopodial branches on short lateral roots but otherwise were similar to those on Pinus. Naturally occurring mycorrhizas formed by B. edulis on Q. robur were very similar to those on Betula established in the laboratory although they tended to be darker coloured. Cystidia were frequently seen. The next step in our research will be to develop ways of infecting large numbers of Pinus radiata with B. edulis for use in New Zealand plantation forestry. It is hoped that the harvest of B. edulis between February and April and sale out-of-season in the Northern Hemisphere will enhance the income from these forests.
Bibliography Arora, D. 1986. Mushrooms demystified. Ten Speed Press, Berkeley, USA. Breitenbach, J.; F. Kränzlin. 1991. Fungi of Switzerland Vol. 3. Boletes and agarics Isp Part. Sticher Printing AG. Lucerne, Switzerland. Hall, I.R.; Buchanan, P.K.; Wang, Y.; Cole, A.L.J. 1998. Edible and poisonous mushrooms:
an introduction. New Zealand Institute for Crop & Food Research, Christchurch. Hall, I.R.; Lyon, A.J.E.; Wang, Y.; Sinclair, L. 1998. Ectomycorrhizal fungi with edible fruiting bodies. 2. Boletus edulis. Economic botany 52: 44-56. Hall, I.R.; Wang, Y. 1998. Methods for cultivating edible ectomycorrhizal mushrooms. In: Mycorrhiza manual, ed. A. Varma. Springer Laboratory Manual. Springer Verlag, Heidelberg. Pp 99-114. Marais, L.J.; J.M. Kotzé. 1977. Notes on ectotrophic mycorrhizae of Pinus patula in South Africa. South African Forestry Journal 100:61-71. Pearson, A.A. 1950. Cape agarics and boleti. Transactions of the British Mycological Society 33:276-316. Phillips, R. 1981. Mushrooms and other fungi of Great Britain and Europe. Pan, London, UK. Van der Westhuizen, G.C.A. 1983. Mushrooms and toadstools: a guide to the common edible, inedible and poisonous South African species. Bulletin 396, South African Department of Agriculture, South Africa. Wang, Y.; Hall, I.R.; Sinclair, L.; Cole, A.L.J. 1995. Boletus edulis sensu lato: A new record for New Zealand. New Zealand journal of crop and Horticultural Science 23: 227-231. Zang, M.; Bi, Z.S. 1991. Edible fungal flora of China. China Forestry Publishing House, Beijing,
