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    锰对外生菌根真菌生长、养分吸收及有机酸分泌的影响

    Effects of manganese on growth, nutrient uptake and organic acid exudation by ectomycorrhizal fungi.

    • 摘要: 在液体培养条件下,研究了不同质量浓度锰对外生菌根真菌Pt 715、Sl 13和Cg 04菌丝生长、草酸和乙酸分泌,以及氮、磷、钾吸收的影响。结果表明:Pt 715的生物量最高, Sl 13次之,Cg 04最低。锰显著抑制菌丝生长,菌丝生物量(y)与培养基中的锰质量浓度(0~800 mg/L)呈y=ax+b的关系(a0);但锰对Pt 715和Sl 13生长的抑制作用较小,说明这2株外生菌根真菌抗锰能力较强,其原因可能是它们长期生存于活性锰含量较高的酸性土壤中,产生了环境适应性,逐渐进化出对锰的抗性。此外,Cg 04和Pt 715不分泌乙酸,但分泌草酸的速率随锰质量浓度的增加而提高;Sl 13能分泌乙酸,在锰质量浓度较高时,分泌草酸的速率显著降低,说明分泌草酸络合锰可能不是外生菌根真菌抗锰的唯一生化途径。Pt 715和Sl 13的氮、磷、钾吸收量显著高于Cg 04。在培养基中添加锰尤其是较高质量浓度的锰(800 mg/L),Pt 715和Sl 13吸收养分的降幅显著低于Cg 04(除氮外),降幅比Cg 04低20.28%~15.44%(磷)和51.20%~27.27%(钾)。在锰胁迫条件下,菌丝保持较强的养分吸收能力有益于细胞的健康,增强其抗锰能力,对于提高寄主植物的抗锰能力也可能有积极意义。

       

      Abstract: Ectomycorrhizal fungi Cenococcum geophilum 04 (Cg 04), Pisolithus tinctorius 715 (Pt 715) and Suillus luteus 13 (Sl 13) were grown in liquid culture media to investigate the effects of manganese (Mn) on fungal growth, organic acid exudation (oxalate and acetate) and nutrient uptake (nitrogen, phosphorus and potassium). The results showed that Pt 715 had the highest biomass, followed by Sl 13 and Cg 04 was the lowest. Mn2+ was harmful to fungal growth and y=ax+b(a0)could express the relations between hyphae biomasses (y) and Mn concentrations (x) in the culture medium, where Mn2+ ranged from 0 to 800 mg/L. Less inhibition on the growth of Pt 715 and Sl 13 than Cg 04 under Mn stress suggests higher abilities of Pt 715 and Sl 13 against Mn toxicity. The reason for this could be explained by environmental adaptation and evolution for manganese resistance due to longterm survival in acidic soils with high available Mn. Moreover, both Cg 04 and Pt 715 exuded oxalate but not acetate into liquid culture media as Mn concentrations increased. In contrast, Sl 13 could release acetate, and the oxalate exudation rate decreased with increasing Mn concentrations. Therefore, the complexing of Mn with oxalate exuded by ecotmycorrhizal fungi might not be the sole biochemical pathway against Mn toxicity. More nitrogen, phosphorus and potassium were absorbed by Pt 715 and Sl 13 than Cg 04 In the culture media, particularly with high Mn concentration (800 mg/L), Cg 04 absorbed less nutrient (except nitrogen) than Pt 715 and Sl 13 The scale of nutrient uptake by Pt 715 and Sl 13 was 20.8%-15.44%(phosphorus) and 51.20%-27.27% (potassium) less than Cg 04 High nutrient uptake could benefit fungal cell health and Mn tolerance, which could also improve the ability of host plants for Mn resistance.

       

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