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对各种含氮基质、葡萄糖和(或)根浸出液中培养的丛枝菌根真菌Glomus intraradices孢子,在萌发过程中对不同氮素的利用及其氨基酸的生物合成进行了研究.用稳定同位素标记及质谱仪来分析不同氮素的利用和氨基酸的生物合成.以高效液相色谱测量氨基酸的浓度.在缺少外源氮素的情况下,丛枝菌根真菌孢子萌发时可以利用内部储存的含氮化合物生物合成游离氨基酸.其中,丝氨酸和甘氨酸是大量合成的氨基酸.合成的氨基酸浓度在2周内随着萌发时间的增加而增加.在有可利用的外源无机氮(铵盐、硝酸盐和尿素)和有机氮(氨基酸)时,铵盐和尿素比硝酸盐更容易被AM真菌萌发孢子利用,而其利用氨基酸中的氮比无机氮源慢的多.孢子吸收同化外源无机氮,且将其整合到游离氨基酸中,这些新生氨基酸浓度比无外源氮添加时要高得多.在无葡萄糖添加的硝酸盐培养液中,AM真菌孢子中积累大量天冬酰胺.然而,在含有葡萄糖的培养液中,萌发孢子因葡萄糖的吸收促进了对外源氮的吸收,产生的游离氨基酸是无葡萄糖时的5倍,并且发现精氨酸转为含量最多的游离氨基酸.并且,从外源氮吸收同化的氮可以储存于精氨酸中,随之,精氨酸被整合到AM真菌孢子储存的蛋白质中.此外,根浸出原液在AM真菌孢子萌发2周后对氮的吸收作用不明显.
The arbuscular mycorrhizal fungi Glomus intraradices spores cultured in various nitrogen-containing substrates, glucose and (or) root leachate were used to study the utilization of different nitrogen sources and their amino acid biosynthesis in the germination process. Stable isotope labeling And mass spectrometry to analyze the utilization of different nitrogen and the biosynthesis of amino acids.Amino acid concentrations were measured by high performance liquid chromatography.In the absence of exogenous nitrogen, the arbuscular mycorrhizal fungi spores germinate using the internally-stored Nitrogen compounds biosynthesis of free amino acids, of which, serine and glycine are a large number of synthetic amino acids.A synthetic amino acid concentration increased with the germination time increases within 2 weeks.In the presence of available exogenous inorganic nitrogen (ammonium, nitrate And urea), and organic nitrogen (amino acids), ammonium and urea are more easily utilized by AM fungi than spores of nitrate, whereas nitrogen in their utilized amino acids is much slower than inorganic nitrogen sources. Spore absorption assimilates exogenous inorganic nitrogen, And they are integrated into free amino acids, these nascent amino acids concentration is much higher than when no exogenous nitrogen is added.In the nitrate-free medium with glucose addition, AM fungi However, in the medium containing glucose, germination of spores due to the absorption of glucose promoted the absorption of exogenous nitrogen, resulting in 5 times as much free amino acid as glucose-free, and arginine turnover Is the most abundant free amino acid, and the assimilated nitrogen absorbed from the exogenous nitrogen can be stored in arginine, followed by arginine being incorporated into the protein stored in the spores of AM fungi.In addition, Spore germination after two weeks of nitrogen absorption is not obvious.