Expressed nifH Genes of Endophytic Bacteria Detected in Field-Grown Sweet Potatoes (Ipomoea batatas L.)

Terakado-Tonooka, Junko; Ohwaki, Yoshinari; Yamakawa, Hiromoto; Tanaka, Fukuyo; Yoneyama, T.; Fujihara, Shinsuke

doi:10.1264/jsme2.23.89

Cited by 72 publications

(58 citation statements)

References 45 publications

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“…This indicated that this gene was induced under the treatment without a nitrogen source. Similarly, TerakadoTonooka et al (34) suggested that bradyrhizobia colonize and express the nifH gene not only in the root nodules of leguminous plants but also in sweet potatoes as diazotrophic endophytes. However, it has been observed that R. leguminosarum bv.…”

Section: Discussionmentioning

confidence: 99%

Potential of Rice Stubble as a Reservoir of Bradyrhizobial Inoculum in Rice-Legume Crop Rotation

Piromyou

Greetatorn

Teamtisong

et al. 2017

Appl Environ Microbiol

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Bradyrhizobium encompasses a variety of bacteria that can live in symbiotic and endophytic associations with leguminous and nonleguminous plants, such as rice. Therefore, it can be expected that rice endophytic bradyrhizobia can be applied in the rice-legume crop rotation system. Some endophytic bradyrhizobial strains were isolated from rice (Oryza sativa L.) tissues. The rice biomass could be enhanced when supplementing bradyrhizobial strain inoculation with KNO 3 , NH 4 NO 3 , or urea, especially in Bradyrhizobium sp. strain SUTN9-2. In contrast, the strains which suppressed rice growth were photosynthetic bradyrhizobia and were found to produce nitric oxide (NO) in the rice root. The expression of genes involved in NO production was conducted using a quantitative reverse transcription-PCR (qRT-PCR) technique. The nirK gene expression level in Bradyrhizobium sp. strain SUT-PR48 with nitrate was higher than that of the norB gene. In contrast, the inoculation of SUTN9-2 resulted in a lower expression of the nirK gene than that of the norB gene. These results suggest that SUT-PR48 may accumulate NO more than SUTN9-2 does. Furthermore, the nifH expression of SUTN9-2 was induced in treatment without nitrogen supplementation in an endophytic association with rice. The indole-3-acetic acid (IAA) and 1-amino-cyclopropane-1-carboxylic acid (ACC) deaminase produced in planta by SUTN9-2 were also detected. Enumeration of rice endophytic bradyrhizobia from rice tissues revealed that SUTN9-2 persisted in rice tissues until rice-harvesting season. The mung bean (Vigna radiata) can be nodulated after rice stubbles were decomposed. Therefore, it is possible that rice stubbles can be used as an inoculum in the rice-legume crop rotation system under both low-and high-organic-matter soil conditions.IMPORTANCE This study shows that some rice endophytic bradyrhizobia could produce IAA and ACC deaminase and have a nitrogen fixation ability during symbiosis inside rice tissues. These characteristics may play an important role in rice growth promotion by endophytic bradyrhizobia. However, the NO-producing strains should be of concern due to a possible deleterious effect of NO on rice growth. In addition, this study reports the application of endophytic bradyrhizobia in rice stubbles, and the rice stubbles were used directly as an inoculum for a leguminous plant (mung bean). The degradation of rice stubbles leads to an increased number of SUTN9-2 in the soil and may result in increased mung bean nodulation. Therefore, the persistence of endophytic bradyrhizobia in rice tissues can be developed to use rice stubbles as an inoculum for mung bean in a ricelegume crop rotation system. KEYWORDS rice endophytic bradyrhizobia, mung bean, rice-legume crop rotation

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Section: Discussionmentioning

confidence: 99%

Potential of Rice Stubble as a Reservoir of Bradyrhizobial Inoculum in Rice-Legume Crop Rotation

Piromyou

Greetatorn

Teamtisong

et al. 2017

Appl Environ Microbiol

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“…Although there have been many attempts to describe the diversity of nifH gene pools in environmental samples (6,7,9,12,19,30,31,33), few studies have simultaneously displayed both qualitative and quantitative differences in nifH gene composition (18,26,27,32). Phylogenetic trees have been frequently used to describe visually the microbial diversity in diverse environments.…”

Section: Diversity Of the Nifh Gene In The Rhizosphere Of M Malabathmentioning

confidence: 99%

Analysis of Diversity of Diazotrophic Bacteria Associated with the Rhizosphere of a Tropical Arbor, Melastoma malabathricum L.

et al. 2009

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The diversity of diazotrophic bacteria in the rhizosphere of Melastoma malabathricum L. was investigated by cloning-sequencing of the nifH gene directly amplified from DNA extracted from soil. Samples were obtained from the rhizosphere and bulk soil of M. malabathricum growing in three different soil types (acid sulfate, peat and sandy clay soils) located very close to each other in south Kalimantan, Indonesia. Six clone libraries were constructed, generated from bulk and rhizosphere soil samples, and 300 nifH clones were produced, then assembled into 29 operational taxonomic units (OTUs) based on percent identity values. Our results suggested that nifH gene diversity is mainly dependent on soil properties, and did not differ remarkably between the rhizosphere and bulk soil of M. malabathricum except in acid sulfate soil. In acid sulfate soil, as the Shannon diversity index was lower in rhizosphere than in bulk soil, it is suggested that particular bacterial species might accumulate in the rhizosphere.

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“…After 15-years long molecular investigations, we successfully identified the possible candidates of endophytic free-living N 2 -fixing rhizobia habiting in the plant tissues such as sugarcane stems 91) and sweet potato petioles. 92) Wild plants, whose roots form the symbiotic system with arbuscular mycorrhiza, show a preference for the uptake of ammonia and amino acids, which are released from decomposing plant residues and whose δ 15 N values are higher than that of the nitrate produced from them by nitrification. Therefore, arbuscular mycorrhiza-infected plants have δ 15 N values, higher than those of non-infected plants, 93) but other types of fungi, i.e., ectomycorrhizal and saprotrophic fungi, do not follow this rule.…”

Section: Introductionmentioning

confidence: 99%

The 1981–2000 Studies of 13C/12C and 15N/14N Discrimination in the Metabolism of Higher Plants, and the Progress Since Then

Expressed nifH Genes of Endophytic Bacteria Detected in Field-Grown Sweet Potatoes (Ipomoea batatas L.)

Cited by 72 publications

References 45 publications

Potential of Rice Stubble as a Reservoir of Bradyrhizobial Inoculum in Rice-Legume Crop Rotation

Potential of Rice Stubble as a Reservoir of Bradyrhizobial Inoculum in Rice-Legume Crop Rotation

Analysis of Diversity of Diazotrophic Bacteria Associated with the Rhizosphere of a Tropical Arbor, Melastoma malabathricum L.

The 1981–2000 Studies of <sup>13</sup>C/<sup>12</sup>C and <sup>15</sup>N/<sup>14</sup>N Discrimination in the Metabolism of Higher Plants, and the Progress Since Then

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