菌丝桥在日本落叶松幼苗间磷传递和植株生长中的作用

 应用四室隔网系统研究了菌丝桥在日本落叶松(Larix kaempferi)幼苗间传递磷的作用。结果表明，供体接种卷缘桩菇(Paxillus involutus)和彩色豆马勃（Pisolithus tinctorius）后，其外延菌丝可以穿过隔离层侵染受体落叶松，在供体和受体落叶松间形成了菌丝桥。供体植株接种菌根真菌后生物量明显增加，但是对受体植株没有显著的影响。菌根真菌侵染的供体和受体植株的根、地上部吸磷量均分别显著高于对照，而且供体植株根、地上部吸磷量增加的程度明显高于受体。被卷缘桩菇和彩色豆马勃侵染的受体植株体内32P的放射性强度分别是对照的10倍和6倍，两者形成菌丝桥后传递到受体植株的32P分别为供体植株体内32P的1.10%和0.22%。供体植株吸收的32P可以通过菌丝桥传递给受体，但是绝对数量十分有限，对受体植株磷营养没有产生显著的影响，但P. involutus和P. tinctorius侵染受体植株后，促进了受体落叶松对磷的吸收，这是菌丝桥形成后，真菌帮助受体植株吸收磷引起的。

THE ROLE OF ECTOMYCORRHIZAL FUNGAL HYPHAL LINKS IN PHOSPHORUS TRANSFER BETWEEN LARIX KAEMPFERI SEEDLINGS AND PLANT GROWTH

A four compartment_culture system was designed to study P nutrition and the effects of hyphal links on 32 P transfer among Larix kaempferi seedlings after inoculation with Paxillus involutus and Pisolithus tinctorius. Results showed that both the donor and the receiver can be inoculated with Paxillus involutus and Pisolithus tinctorius, which indicates that the extraradical mycelia of donor larch seedlings could penetrate air gaps and clay soil and form hyphal links between the donor and the receiver. The biomass of donor seedlings inoculated with Paxillus involutus and Pisolithus tinctorius was greater than that of non_mycorrhizal seedlings, but the growth of receiver seedlings was not significantly affected. The amount of P in the shoots and roots of Larix kaempferi inoculated with Paxillus involutus and Pisolithus tinctorius was significantly higher than in controls, and the amount of P in donor seedlings was much greater than in receiver seedlings. The P nutrition of both the donor and receiver plants was improved after they were inoculated with Paxillus involutus and Pisolithus tinctorius. The P content in the donor seedlings was 39% higher than that of the controls accounting for the greater biomass of donor seedlings. The inoculation rate, biomass and P content of receiver seedlings were all lower than that of donor seedlings, most likely because the receiver was inoculated after the donor's inoculation so that the time of inoculation on the receiver was shorter than that of the donor. 32 P in receiver seedlings was checked using radioautography and the concentration of 32 P radioactivity. The 32 P radioactivity of receiver seedlings inoculated with Paxillus involutus and Pisolithus tinctorius was 10 and 6 times higher, respectively, than in controls without hyphal links, and the amount of 32 P in the receiver plants was 1.10% and 0.22% of donor seedlings, respectively. 32 P radioactivity also was found in control plants, indicating that 32 P could diffuse to receiver compartments through the soil and be absorbed by the receiver. The 32 P transfer rate from the donor to the receiver after inoculation with Paxillus involutus and Pisolithus tinctorius was 18 and 4 times higher, respectively, than that of the control indicating that the 32 P in donor seedlings could be transferred to the receiver seedlings via hyphal links. The 32 P transfer rate through hyphal links formed with Paxillus involutus was 4.5 times higher than those formed with Pisolithus tinctorius, which could be attributed to the higher inoculation rate, biomass of extramycelium and hyphal density of Paxillus involutus. 32 P was transferred from the donor to the receiver seedlings via hyphal links, but the amount was very limited. P nutrition of receiver seedlings was not significantly improved, but P absorbed by receiver seedlings increased after inoculation with both Paxillus involutus and Pisolithus tinctorius. This effect was attributed to P acquisition of acceptors aided by fungi after hyphal links formed.