云锦杜鹃菌根真菌吸收氮源特性及其接种效应

Characteristics of Nitrogen Absorbed by Ericoid Mycorrhizal Fungi and Impact on Growth of Rhododendron fortunei

【目的】研究从云锦杜鹃根系分离的欧石南菌根(eriocoid mycorrhiza,ERM)真菌对铵态氮、硝态氮和无机氮吸收特性及其接种效应,检测ERM菌株吸收利用不同氮源能力及筛选培养菌株适宜的氮源,并分析ERM对寄主植物氮源吸收的影响。【方法】采用菌丝干重定量研究菌株的氮源吸收特性;在不同氮源培养基上,采用单菌株接种无菌云锦杜鹃(Rhododendron fortunei)幼苗研究ERM对寄主植物生长的影响。【结果】供试ERM真菌菌株在不同氮源培养基中生长量差异明显,所有菌株在各单一氮源培养基中菌丝干重均增加,其中铵态氮和硝态氮中生长量较大;各氮源培养基上,菌株接种幼苗生长均优于非接种苗,而且在牛血清蛋白培养基上接种苗干重显著高于其它氮源。【结论】铵态氮和硝态氮是供试ERM菌株培养的比较适宜氮源;ERM增加了云锦杜鹃对氮源的吸收,尤其是硝态氮和有机氮的吸收。

[Objective] Research on the characteristics of ammonium, nitrate and organic nitrogen utilization by ericoid mycorrhizal fungi and impacts on growth in vitro of Rhododendron fortunei was carried out to determine the suitable nitrogen sources in ericoid mycorrhizal （ERM） fungal cultivation and test the effects of ERM on host plant growth in substrate with different nitrogen sources. [Method] Mycelial dry weight of ERM fungal strain in the different nitrogen source media was used as the index to assess nitrogen utilization. These ERM fungal strains were also inoculated on seedlings of Rhododendron fortunei on different nitrogen source substrates, and the effect of ERM fungi on the host plant was evaluated by dry weight of the seedlings. [ Result] Nitrogen sources had a significant effect on fungus biomass. Fungal growth was the best on ammonium and nitrate, moderate on arginine and Bovine Serum Albumin （BSA）, and poor on medium without nitrogen. Inoculated plants grew better than non-inoculated plants regardless of nitrogen sources, and grew best on BSA. [Conclusion] Ammonium and nitrate were suitable N source for the growth of the ERM strains. Inoculation with these ERM fungi increased the capacity of Rhododendron fortunei to utilize nitrogen source, especially nitrate and BSA nitrogen.