Symbiotic efficiency and compatibility of native rhizobia in northern Thailand with different soybean cultivars     

Arawan Shutsrirung  Srisook Thamapibool  Ampan Bhromsiri  Keishi Senoo  Shigeyuki Tajima  Makoto Hisamatsu 《Soil Science and Plant Nutrition》2013,59(4):501-510

Symbiotic efficiency and compatibility of 81 isolates of native bradyrhizobia from irrigated areas in northern Thailand with four soybean cultivars and one cowpea cultivar were evaluated under laboratory conditions. Effectiveness and / or compatibility of the tested isolates were compared with those of a standard strain (Bradyrhizobium japonicum CB 1809) by using plants grown on plastic seed bags. Effectiveness of the isolates was also estimated using uninoculated control plants grown in a nitrogen-free solution. Nodulation of a wide range of host plants by the majority of the tested isolates was observed, which agreed well with the results of our previous field experiment (Shutsrirung et al. 2002: Soil Sci. Plant Nutr., 48, 491–499). Up to 75% of the tested isolates induced a higher growth efficiency than that of the uninoculated control in association with one of the tested cultivars, Black soybean. Comparision with uninoculated control plants, enable to estimate the proportion of the tested isolates leading to effective growth promotion (E + e) of each cultivar, namely, Black soybean (local Thai cultivar), 75%; Cowpea, 82%; SJ5 (commercial Thai cultivar), 33%; Bragg (US cultivar), 33%; and Improved Pelican (US cultivar), 9%. These results indicated that although isolates with a high infectiveness with both “Asian-type” and “US-type” soybeans could be found, a high frequency of isolates leading to inefficient nodules was observed in the US cultivar, suggesting the presence of genetic differences in the soybean cultivars that express high-preference (efficient nodules) or low-preference (inefficient nodules) for a certain group of tested isolates. Based on the results of this laboratory experiment together with our previous field experiment, native rhizobial populations in the irrigated area of northern Thailand could be separated into three groups; Group 1: rhizobium strains showing a high effectiveness with only Asian cultivars, Group 2: strains showing a high effectiveness with only US origin cultivars, and Group 3: strains showing a high effectiveness with both Asian and US origin cultivars. The majority of the native rhizobial populations belonged to Group 1. The isolates in Group 3 may display a high potential for manipulating useful rhizobial inoculant.  相似文献   

Characterization of local rhizobia in Thailand and distribution of malic enzymes     

Suphawat Sinsuwongwat  Achara Nuntagij  Arawan Shutsrirung  Mika Nomura  Shigeyuki Tajima 《Soil Science and Plant Nutrition》2013,59(5):719-727

TWenty-six isolates were obtained from nodules of various legume plants (Glycine max, Vigna sinensis, Arachis hypogaea, Desmanthus virgatus, Acacia mangium, Centrosema pascuorum, Pterocarpus indicus, Xylia xylocarpa, and Sesbania rostrata) in Thailand. After confirming their nodulation and nitrogen-fixing abilities, they were identified by 16S rRNA gene analysis as Bradyrhizobium japonicum, Bradyrhizobium elkanii, Rhizobium leguminosarum, Rhizobium gallicum, and Rhizobium galegae. Using these local isolates, the distribution of the activities of both NAD⁺-dependent (DME: EC 1.1.1.39) and NADP⁺-dependent (TME: EC 1.1.1.40) malic enzymes was surveyed. The malic enzyme activities were present in all the isolated rhizobia and in other 17 local Bradyrhizobium strains in Thailand. In almost all the rhizobia, the DME activity predominated whereas the TME activity predominated only in the Rhizobium gallicum strains that were major symbionts of Sesbania rostrata. Southern hybridization analysis was performed to survey the distribution of the malic enzyme genes among the local rhizobia, which are similar to those of B. japonicum. DNA probes (ME1 for DME and ME2 for TME) were prepared by polymerase chain reaction (PCR) using degenerated primers from conserved regions of the protein sequences of bacterial malic enzymes. Southern blot analysis with ME1 as a probe showed a single band in about half of the isolates, especially in B. japonicum and R. leguminosarum strains, suggesting the wide distribution of such DME genes among local rhizobia. In contrast, Southern blot analysis with ME2 as a probe detected a single band only in five B. japonicum strains, suggesting that the TME genes, which are similar to those of B. japonicum, would be unique in a group of B. japonicum.  相似文献   

Simple method of genomic DNA extraction from Rhizobia in dried nodules of Phaseolus vulgaris for strain differentiation by PCR-based DNA fingerprinting     

Choochad Santasup  Keishi Senoo  Ampan Bhromsiri  Arawan Shutsrirung  Akiyoshi Tanaka  Hitoshi Obata 《Soil Science and Plant Nutrition》2013,59(2):541-548

Repetitive DNA peR fingerprinting of bacterial genomic DNA is a useful tool for typing and differentiation of rhizobial strains. The method was reported to be suitable for strain differentiation of Rhizobia present in individual root nodules of some leguminous plants without the need for isolation and cultivation of the strains, in which rhizobial genomic DNA was extracted directly from each fresh or frozen nodule. We developed a new protocol of rhizobial genomic DNA extraction/purification from dried nodules of Phaseolus vulgaris for generating repetitive DNA peR fingerprints of Rhizobia present in the nodules. The simplified protocol consists of only three major steps, heat extraction of genomic DNA from rhizobial cells prepared from dried nodules, ethanol precipitation of the DNA and Sephadex G-50 column purification of the DNA, and generated fingerprints with good quality for differentiation of Rhizobia strains. The protocol will be useful to examine the nodule occupancy of inoculated rhizobial strains in field experiments.  相似文献   

Diversity of endophytic actinomycetes in mandarin grown in northern Thailand,their phytohormone production potential and plant growth promoting activity     

Arawan Shutsrirung  Yupa Chromkaew  Wasu Pathom-Aree  Somporn Choonluchanon  Nantakorn Boonkerd 《Soil Science and Plant Nutrition》2013,59(3):322-330

Abstract

The rapid expansion of mandarin (Citrus reticulata L.) production areas with high agrochemical input in the highland areas of northern Thailand has resulted in negative effects in terms of production, environment, soil quality, and public health. The use of microorganisms as plant growth promoters is an alternative method to reduce agrochemical input. Thus, we studied the diversity of endophytic actinomycetes in mandarin and their potential as plant growth promoters. A total of 252 endophytic actinomycete isolates were recovered from mandarin. Based on spore chain morphology, cell wall type, and 16S rRNA gene sequence, the isolates were classified into six genera: Streptomyces, Nocardia, Nocardiopsis, Spirillospora, Microbispora and Micromonospora. The most frequent isolates recovered were members of Streptomyces (85.3%). Selected isolates (64 isolates) from these genera were evaluated for their indole-3-acetic acid (IAA) production potential in a medium with 2 mg mL^?1 tryptophan, and all the selected isolates showed the potential to produce IAA, with average values of IAA production of 13.34, 3.36, 140.38, 12.55, 1.40, and 6.19 µg IAA mL^?1, respectively. Isolates of genus Nocardiopsis showed a very high ability to produce IAA that was the highest among all the genera, with values ranging from 62.23 to 222.75 µg mL^?1. Twelve isolates selected from these genera were inoculated onto mandarin seedlings, and the results indicated that the shoot height, fresh shoot weight and fresh root weight of the seedlings were promoted by the inoculation of endophytic actinomycetes, with values ranging from 20.2 to 49.1%, 14.9 to 53.6%, and 1.6 to 102% over the control, respectively.  相似文献