Abstract:

Abstract: Systematic studies of the biological characteristic including morphology, culture, physiological group, cell-wall type, nutrient utilization, nitrogenase activity and host specificity, were carried out on 12 strains isolated from the root nodules of actinorhizal plants of Myrica rubra, comparing with five Frankia strains symbiotically associated with Casuaria cunninghamiana, C. equisetifolia, C. glauca and Alnus cremastogyne. As a result, all strains tested showed a typical Frankia morphology, with filamentous hyphae, multilocular sporangia and vesicles. The specialized reproductive torulose hyphae were found in strains FMr16 and FMr43 from Myrica same as strains FCc64 and FCe33 from Casuarina. Most of strains from Myria formed vesicles in media which nitrogen exited, and nitrogenase activity varied greatly. Cell wall type of many strains belonged to type Ⅲ, except strain FMr16 which was typeⅡ. Strains were found to fall into three physiological groups, one was group A, one was group AB, and the others were group B, both B and AB group strains were found to coexist in a single tree of M. rubra. Strains preferred to utilize sodium propionate, sodium pyruvate, sodium acetate, Tween-80 and NZ amine, but grew poor in presence of saccharide. Some strains utilized potassium nitrate, ammonium sulphate and beef extract, but none of them utilize peptone, urea, glutin and phenylalanine. Strains didn't produce cellulase and H₂S. The result of inoculation showed that strains from M. rubra had an ability to infect the seedlings of M. rubra, A. cremastogyne and Elaeagnus angustifolia, but not infect the seedlings of C. cunninghamiana, C. equisetifolia and C. glauca, so it was a necessary to choose the adaptive strains to use as inoculum.

Key words: Key words: Frankia, Myrica rubra, biological characteristic, physiological group, cell-wall type, host specificity