葡萄糖、根浸出液对丛枝菌根真菌吸收不同外源氮产生精氨酸的影响

以大葱(Allium fistulosum)为宿主植物, 接种丛枝菌根(Arbuscular mycorrhizal, AM)真菌Glomus intraradices, 采用三室隔离盆栽培养系统, 在菌丝室施加浓度为4 mmol/L的不同形态外源氮、1%葡萄糖及根浸出液, 通过测定根外菌丝(Extraradical mycelium, ERM)和菌根中精氨酸的含量, 探究葡萄糖、根浸出液对AM真菌吸收不同形式外源氮产生精氨酸的影响。结果表明, 不同外源氮对ERM中精氨酸含量的影响为尿素>Gln>NH₄NO₃>Arg/Gly>NH₄Cl>KNO₃, 对菌根中精氨酸含量的影响为Arg>Gln>尿素>NH₄NO₃>Gly>NH₄Cl>KNO₃; 施加葡萄糖和根浸出液在不同程度上提高ERM干重和菌丝室孢子数量, 但使ERM和菌根中的精氨酸含量降低。说明AM真菌吸收同化不同外源氮产生精氨酸的能力不同, 葡萄糖和根浸出液降低AM真菌吸收同化外源氮产精氨酸的能力。

Effects of glucose, root exudates on the assimilation of different forms of nitrogen and production of arginine by Arbuscular mycorrhizal fungus

Arbuscular mycorrhizal (AM) fungus (Glomus intraradices) was inoculated to the host plant (Allium fistulosum) and grown in three-part pot culture system, with addition of 4 mmol/L different forms of exogenous nitrogen, 1% glucose and root exudates into the mycelium compartment, effects of glucose and root exudates on the assimilation of different forms of nitrogen and production of arginine by arbuscular mycorrhizal fungus were examined by measuring arginine contents of the extraradical mycelium (ERM) and mycorrhizal roots. The results showed that the absorption capacity of ERM to different forms of exogenous nitrogen and produce arginine is ranked in order of Urea>Gln>NH₄NO₃>Arg/Gly>NH₄Cl>KNO₃; The capability of arginine formation in mycorrhizal roots was ranked in order of Arg>Gln>Urea>NH₄NO₃>Gly>NH₄Cl>KNO₃. Glucose and root exudates increased the dry weight of ERM and spore amount, but reduced arginine concentration in ERM and mycorrhizal roots. These re-sults indicated that the capacity of assimilation of different forms of exogenous nitrogen by AM fungus were different, glucose and root exudates reduced the capacity of assimilation of exogenous nitrogen and production of arginine by AM fungus.