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The Effect of Some External Factors on Nitrogenase Activity in the Free‐Living and Endophytic Nostoc of the Liverwort Blasia pusilla
Author(s) -
RODGERS G. A.
Publication year - 1978
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1978.tb01646.x
Subject(s) - nitrogenase , endophyte , nostoc , algae , nitrogen fixation , biology , botany , symbiosis , cyanobacteria , light intensity , bacteria , physics , optics , genetics
The effects of pH, light intensity, temperature, oxygen and dehydration on nitrogenase activity in the free‐living and endophytic Nostoc sp. of Blasia are described. The endophyte exhibits greater nitrogenase activity at lower pH's than the free‐living alga. Maximal activity in the free‐living alga is attained at much lower light intensities than those required by the endophyte. Both algae have low activities below 10°C, the free‐living alga showing high activity above 12°C and the endophyte above 17°C. Increasing pO 2 levels cause a decrease in activity in both algae. The free‐living alga is more tolerant to dehydration than the endophyte, although both algae are protected by mucilage. The results are discussed and possible benefits resulting from the symbiosis, with respect to nitrogen fixation rates, considered.