Ray T B, Peters G A, Toia R E, Mayne B C
Charles F. Kettering Research Laboratory, 150 East South College Street, Yellow Springs, Ohio 45387.
Plant Physiol. 1978 Sep;62(3):463-7. doi: 10.1104/pp.62.3.463.
The N(2)-fixing Azolla-Anabaena symbiotic association is characterized in regard to individual host and symbiont contributions to its total chlorophyll, protein, and levels of ammonia-assimilating enzymes. The phycocyanin content of the association and the isolated blue-green algal symbiont was used as a standard for this characterization. Phycocyanin was measured by absorption and fluorescence emission spectroscopy. The phycocyanin content and total phycobilin complement of the symbiotic algae were distinct from those of Anabaena cylindrica and a free-living isolate of the Azolla endophyte. The algal symbiont accounted for less than 20% of the association's chlorophyll and protein. Acetylene reduction rates in the association (based solely on the amount of algal chlorophyll) were 30 to 50% higher than those attained when the symbiont was isolated directly from the fern. More than 75% of the association's glutamate dehydrogenase and glutamine synthetase activities are contributed by the host plant. The specific activity of glutamate dehydrogenase is greater than that of glutamine synthetase in the association and individual partners. Both the host and symbiont have glutamate synthase activity. The net distribution of these enzymes is discussed in regard to the probable roles of the host and symbiont in the assimilation of ammonia resulting from N(2) fixation by the symbiont.
固氮满江红-鱼腥藻共生体在宿主和共生体对其总叶绿素、蛋白质以及氨同化酶水平的个体贡献方面具有特征。该共生体和分离出的蓝藻共生体中的藻蓝蛋白含量被用作此特征描述的标准。藻蓝蛋白通过吸收光谱和荧光发射光谱进行测量。共生藻类的藻蓝蛋白含量和总藻胆蛋白组成与圆柱鱼腥藻以及满江红内生菌的一个自由生活分离株不同。藻类共生体占共生体叶绿素和蛋白质的比例不到20%。共生体（仅基于藻类叶绿素的量）的乙炔还原率比直接从蕨类植物中分离出共生体时的乙炔还原率高30%至50%。宿主植物贡献了共生体中超过75%的谷氨酸脱氢酶和谷氨酰胺合成酶活性。在共生体和各个共生伙伴中，谷氨酸脱氢酶的比活性大于谷氨酰胺合成酶。针对宿主和共生体在共生体固氮产生的氨同化中的可能作用，讨论了这些酶的净分布情况。
