Bradyrhizobia are known symbiotic partners of soybean. However, some soybean cultivars restrict nodulation by some Bradyrhizobium bacterial strains. These restrictions are related to compatibility between the Rj genes...Bradyrhizobia are known symbiotic partners of soybean. However, some soybean cultivars restrict nodulation by some Bradyrhizobium bacterial strains. These restrictions are related to compatibility between the Rj genes of soybean cultivars and nodulation types of inoculated bacteria. The objective of this study was to determine nodulation incompatibility of Type B strains with Rj3 soybean cultivars. Newly isolated B. elkanii strains BLY3-8 and BLY6-1 from Myanmar and specific strain Bradyrhizobium elkanii USDA33, which are incompatible with Rj3 soybean cultivars, and B. japonicum USDA110 were used as inoculants to check compatibility or incompatibility with Rj3 soybean cultivars. Nitrogen fixation activity was measured by the acetylene reduction method. Ethylene concentration (reduction of acetylene) was determined by flame ionization gas chromatography. According to the inoculation test results, USDA110 was compatible with all soybean cultivars because it formed effective nodules (Figure S1 in Appendix) and possessed nitrogenase activity. Similarly, B. elkanii strains BLY3-8, BLY6-1, and USDA33 were highly compatible with non-Rj and Rj4-gene harboring soybean cultivars because they had the ability to form functional nodules and possessed nitrogenase activity. Inversely, BLY3-8, BLY6-1, and USDA33 were incompatible with Rj3 soybean cultivars because they produced ineffective nodules. Consequently, the ratio of ineffective nodule number to total nodule number was >0.5. Therefore, nodule formation by the newly isolated B. elkanii strains BLY3-8 and BLY6-1 was restricted by the Rj3 soybean cultivars potentially making them useful as specific strains to detect the Rj3 gene in soybean cultivars.展开更多
Soybean (Glycine max L.) plays an essential role in human nutrition as a protein source, and in plant nutrition as a N source. The rate of N fixation varies depending on the cultivars and compatibility between the ino...Soybean (Glycine max L.) plays an essential role in human nutrition as a protein source, and in plant nutrition as a N source. The rate of N fixation varies depending on the cultivars and compatibility between the inoculated Rhizobium strain and the host cultivar. Characterizing the nodulation regulatory (Rj) genes is necessary to determine the compatibility of cultivars and Rhizobium strains. Rj genes were previously identified based on inoculation tests and PCR analyses. The six cultivars Yezin-3, Yezin-7, Yezin-11, Shan Seine (Local), Madaya (Local), and Hinthada (Local) were identified as harboring the Rj4 gene. Two cultivars, Yezin-6 and Yezin-8, were classified as non-Rj-gene harboring. Two other cultivars, Yezin-9 and Yezin-10, were identified as Rj3- and Rj2Rj3-gene harboring, respectively. Ours is the first report on Rj3- and Rj2Rj3-gene harboring cultivars in Myanmar. We evaluated Myanmar soybean cultivars for symbiotic effectiveness, relying on the standard strain Bradyrhizobium japonicum USDA110. In our first experiment, the soybean cultivar Yezin-11 (Rj4) showed the highest N fixing potential. Based on their potential for fixing N and nodulation, the top six soybean cultivars were Yezin-11 (Rj4), Yezin-9 (Rj3), Yezin-6 (non-Rj), Yezin-8 (non-Rj), Yezin-3 (Rj4) and Yezin-10 (Rj2Rj3). These cultivars were selected for a second experiment, which revealed that the N fixation, nodulation, and plant growth of Yezin-11 (Rj4) *Corresponding author. A. Z. Htwe et al. 2800 were superior to the other cultivars. We conclude that Yezin-11 (Rj4) is the most efficient cultivar for nodulation and N fixation when inoculated with B. japonicum USDA110.展开更多
文摘Bradyrhizobia are known symbiotic partners of soybean. However, some soybean cultivars restrict nodulation by some Bradyrhizobium bacterial strains. These restrictions are related to compatibility between the Rj genes of soybean cultivars and nodulation types of inoculated bacteria. The objective of this study was to determine nodulation incompatibility of Type B strains with Rj3 soybean cultivars. Newly isolated B. elkanii strains BLY3-8 and BLY6-1 from Myanmar and specific strain Bradyrhizobium elkanii USDA33, which are incompatible with Rj3 soybean cultivars, and B. japonicum USDA110 were used as inoculants to check compatibility or incompatibility with Rj3 soybean cultivars. Nitrogen fixation activity was measured by the acetylene reduction method. Ethylene concentration (reduction of acetylene) was determined by flame ionization gas chromatography. According to the inoculation test results, USDA110 was compatible with all soybean cultivars because it formed effective nodules (Figure S1 in Appendix) and possessed nitrogenase activity. Similarly, B. elkanii strains BLY3-8, BLY6-1, and USDA33 were highly compatible with non-Rj and Rj4-gene harboring soybean cultivars because they had the ability to form functional nodules and possessed nitrogenase activity. Inversely, BLY3-8, BLY6-1, and USDA33 were incompatible with Rj3 soybean cultivars because they produced ineffective nodules. Consequently, the ratio of ineffective nodule number to total nodule number was >0.5. Therefore, nodule formation by the newly isolated B. elkanii strains BLY3-8 and BLY6-1 was restricted by the Rj3 soybean cultivars potentially making them useful as specific strains to detect the Rj3 gene in soybean cultivars.
文摘Soybean (Glycine max L.) plays an essential role in human nutrition as a protein source, and in plant nutrition as a N source. The rate of N fixation varies depending on the cultivars and compatibility between the inoculated Rhizobium strain and the host cultivar. Characterizing the nodulation regulatory (Rj) genes is necessary to determine the compatibility of cultivars and Rhizobium strains. Rj genes were previously identified based on inoculation tests and PCR analyses. The six cultivars Yezin-3, Yezin-7, Yezin-11, Shan Seine (Local), Madaya (Local), and Hinthada (Local) were identified as harboring the Rj4 gene. Two cultivars, Yezin-6 and Yezin-8, were classified as non-Rj-gene harboring. Two other cultivars, Yezin-9 and Yezin-10, were identified as Rj3- and Rj2Rj3-gene harboring, respectively. Ours is the first report on Rj3- and Rj2Rj3-gene harboring cultivars in Myanmar. We evaluated Myanmar soybean cultivars for symbiotic effectiveness, relying on the standard strain Bradyrhizobium japonicum USDA110. In our first experiment, the soybean cultivar Yezin-11 (Rj4) showed the highest N fixing potential. Based on their potential for fixing N and nodulation, the top six soybean cultivars were Yezin-11 (Rj4), Yezin-9 (Rj3), Yezin-6 (non-Rj), Yezin-8 (non-Rj), Yezin-3 (Rj4) and Yezin-10 (Rj2Rj3). These cultivars were selected for a second experiment, which revealed that the N fixation, nodulation, and plant growth of Yezin-11 (Rj4) *Corresponding author. A. Z. Htwe et al. 2800 were superior to the other cultivars. We conclude that Yezin-11 (Rj4) is the most efficient cultivar for nodulation and N fixation when inoculated with B. japonicum USDA110.
