Phylogenetic Diversity and Evaluation the Effectiveness of Indigenous Bradyrhizobium Strains for Myanmar Black Gram (Vigna mungo L. Hepper) Cultivars

摘要

Black gram (Vigna mungo L. Hepper) is one of the mainleguminous crops that provide chief source of food. Several Bradyrhizobium species are able to induce effective nodules in black gram cultivars. In thepresent study, we characterized forty isolates of indigenous black gram bradyrhizobia from Myanmar based on thesequence analysis of the bacterial 16S rRNA gene. The sequence analysisconfirmed that all isolates were categorized and identified as the genus Bradyrhizobium and they were conspecificwith B . elkanii , B . sp., B . liaoningense , B . japonicum and B . yunamingense .Almost all the collected isolates from major black gram growing regions ofNyaunglebin Bago Regio, Chaungzon Mon State, Sittwe Rakhine State, DanubyuAyeyarwady Region and LaunglonTanintharyi Region were identified as B . liaoningense .At Danubyu Ayeyarwady Region and Pyinmanar Nay Pyi Taw Region, most of thestrains were identified as B . japonicum . On the other hand, more or less all theisolates from Launglon Tanintharyi Region and Hpa-an Kayin State were relatedto B . elkanii . However, all B . sp. strains were found in SalingyiSagaing Region black gram growing region. This is the first report describing Bradyrhizobium strains that were isolated from soil samples of majorblack gram growing areas in Myanmar. Evaluationof the effectiveness of Myanmar Bradyrhizobim strains isolated from soil samples of major black gram growing areas of Myanmarfor plant growth and nitrogen fixation was studied in pot experiments with completely randomized design and threereplicates. The nodule dry weight, shoot dry weight and acetylene reductionactivity of the plant inoculated with Bradyrhizobium elkanii LauBG38 were significantly higher in ARA per plant,nodule and shoot dry weights than the other tested isolates in both Yezin-4 andYezin-7 black gram varieties. We expect that Myanmar Bradyrhizobium elkanii LauBG38 will be able to use asBiofertilizer for black gram cultivars.