磷和镉对根内球囊霉Glomus intraradices孢子萌发、菌丝生长和外生菌丝内聚磷酸累积的影响

丛枝菌根真菌(AMF)能够显著提高植物对重金属的抗性,菌丝内聚磷酸(Polyphosphate,PolyP)可能参与了这种抗性的形成。试验以Glomus intraradices孢子为试材,对灭菌条件进行了优化,并进一步研究了不同P和Cd2+水平对孢子萌发、菌丝生长、分支和外生菌丝中聚磷酸含量的影响。结果表明,孢子在1%氯胺T+0.02%链霉素+0.01%庆大霉素+1/100(V/V)吐温-20中灭菌5min的效果最好。孢子萌发率、菌丝分支和菌丝长度随着Cd2+浓度的增加不断降低;当Cd2+浓度达到0.1mmol/L时,孢子萌发率降低为0%,表明Glomus intraradices的孢子萌发对Cd2+的耐受极限为0.1mmol/L;1mmol/L的P促进菌丝分支增加,却降低了萌发率,但对菌丝生长没有影响;在培养23d以后,三者基本不再变化。外生菌丝内的聚磷酸含量随着P的升高而增加;在Cd2+胁迫作用下,聚磷酸的含量降低而菌丝密度随着聚磷酸的升高而升高,表明聚磷酸在减弱重金属毒性方面起了重要作用。

Influence of P and Cd on the spore germination, hyphal growth and polyphosphate accumulation in extraradical hyphae of Glomus intraradices

Arbuscular mycorrhizal fungi (AMF) can significantly enhance the resistance of plants to heavy metal, and polyphosphate (PolyP) in the hyphae may be involved in the formation of this resistance. Spores of Glomus intraradices were used as experimental material. The sterilization condition was optimized, and the influence of P and Cd2+ on the spore germination, hyphal growth and polyphosphate in external hyphae of G. intraradices was studied. The results indicated that the spore sterilization in the mixture of 1% chloramine T, 0.02% streptomycin, 0.01% gentamicin and 1/100 (V/V) TW-20 for 5min showed the best effect. Spore germination, hyphal branching and hyphal length decreased with the increase of Cd2+ concentration. The spore germination rate was 0% when the Cd2+ concentration reached 0.1mmol/L, indicating the tolerance limit of spores to Cd2+ at 0.1mmol/L. P at 1mmol/L increased hyphal branching, but decreased spore germination rate and did not affected the hyphal length. All three parameters did not change after the incubation for 23 days. PolyP content in extraradical hyphae increased in response to the elevation of P. Under the Cd2+ stress, PolyP content decreased, while hyphal density increased with PolyP content rising, suggesting an important role of PolyP in the alleviation of heavy metal toxicity.