Genotypic Variation of Endophytic Nitrogen-Fixing Activity and Bacterial Flora in Rice Stem Based on Sugar Content

Enhancement of the nitrogen-fixing ability of endophytic bacteria in rice is expected to result in improved nitrogen use under low-nitrogen conditions. Endophytic nitrogen-fixing bacteria require a large amount of energy to fix atmospheric nitrogen. However, it is unknown which carbon source and bac...

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Main Authors: Takanori Okamoto, Rina Shinjo, Arisa Nishihara, Kazuma Uesaka, Aiko Tanaka, Daisuke Sugiura, Motohiko Kondo
Format: Article
Language:English
Published: Frontiers Media S.A. 2021-08-01
Series:Frontiers in Plant Science
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/fpls.2021.719259/full
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spelling doaj-623e77bcde0846cba781a6c9c59ae6512021-08-10T08:04:58ZengFrontiers Media S.A.Frontiers in Plant Science1664-462X2021-08-011210.3389/fpls.2021.719259719259Genotypic Variation of Endophytic Nitrogen-Fixing Activity and Bacterial Flora in Rice Stem Based on Sugar ContentTakanori Okamoto0Rina Shinjo1Arisa Nishihara2Kazuma Uesaka3Aiko Tanaka4Daisuke Sugiura5Motohiko Kondo6Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, JapanGraduate School of Bioagricultural Sciences, Nagoya University, Nagoya, JapanBioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, JapanCenter for Gene Research, Nagoya University, Nagoya, JapanGraduate School of Bioagricultural Sciences, Nagoya University, Nagoya, JapanGraduate School of Bioagricultural Sciences, Nagoya University, Nagoya, JapanGraduate School of Bioagricultural Sciences, Nagoya University, Nagoya, JapanEnhancement of the nitrogen-fixing ability of endophytic bacteria in rice is expected to result in improved nitrogen use under low-nitrogen conditions. Endophytic nitrogen-fixing bacteria require a large amount of energy to fix atmospheric nitrogen. However, it is unknown which carbon source and bacteria would affect nitrogen-fixing activity in rice. Therefore, this study examined genotypic variations in the nitrogen-fixing ability of rice plant stem as affected by non-structural carbohydrates and endophytic bacterial flora in field-grown rice. In the field experiments, six varieties and 10 genotypes of rice were grown in 2017 and 2018 to compare the acetylene reduction activity (nitrogen-fixing activity) and non-structural carbohydrates (glucose, sucrose, and starch) concentration in their stems at the heading stage. For the bacterial flora analysis, two genes were amplified using a primer set of 16S rRNA and nitrogenase (NifH) gene-specific primers. Next, acetylene reduction activity was correlated with sugar concentration among genotypes in both years, suggesting that the levels of soluble sugars influenced stem nitrogen-fixing activity. Bacterial flora analysis also suggested the presence of common and genotype-specific bacterial flora in both 16S rRNA and nifH genes. Similarly, bacteria classified as rhizobia, such as Bradyrhizobium sp. (Alphaproteobacteria) and Paraburkholderia sp. (Betaproteobacteria), were highly abundant in all rice genotypes, suggesting that these bacteria make major contributions to the nitrogen fixation process in rice stems. Gammaproteobacteria were more abundant in CG14 as well, which showed the highest acetylene reduction activity and sugar concentration among genotypes and is also proposed to contribute to the higher amount of nitrogen-fixing activity.https://www.frontiersin.org/articles/10.3389/fpls.2021.719259/fullbacterial floraendophytenifHnitrogen fixationnon-structural carbohydraterice
collection DOAJ
language English
format Article
sources DOAJ
author Takanori Okamoto
Rina Shinjo
Arisa Nishihara
Kazuma Uesaka
Aiko Tanaka
Daisuke Sugiura
Motohiko Kondo
spellingShingle Takanori Okamoto
Rina Shinjo
Arisa Nishihara
Kazuma Uesaka
Aiko Tanaka
Daisuke Sugiura
Motohiko Kondo
Genotypic Variation of Endophytic Nitrogen-Fixing Activity and Bacterial Flora in Rice Stem Based on Sugar Content
Frontiers in Plant Science
bacterial flora
endophyte
nifH
nitrogen fixation
non-structural carbohydrate
rice
author_facet Takanori Okamoto
Rina Shinjo
Arisa Nishihara
Kazuma Uesaka
Aiko Tanaka
Daisuke Sugiura
Motohiko Kondo
author_sort Takanori Okamoto
title Genotypic Variation of Endophytic Nitrogen-Fixing Activity and Bacterial Flora in Rice Stem Based on Sugar Content
title_short Genotypic Variation of Endophytic Nitrogen-Fixing Activity and Bacterial Flora in Rice Stem Based on Sugar Content
title_full Genotypic Variation of Endophytic Nitrogen-Fixing Activity and Bacterial Flora in Rice Stem Based on Sugar Content
title_fullStr Genotypic Variation of Endophytic Nitrogen-Fixing Activity and Bacterial Flora in Rice Stem Based on Sugar Content
title_full_unstemmed Genotypic Variation of Endophytic Nitrogen-Fixing Activity and Bacterial Flora in Rice Stem Based on Sugar Content
title_sort genotypic variation of endophytic nitrogen-fixing activity and bacterial flora in rice stem based on sugar content
publisher Frontiers Media S.A.
series Frontiers in Plant Science
issn 1664-462X
publishDate 2021-08-01
description Enhancement of the nitrogen-fixing ability of endophytic bacteria in rice is expected to result in improved nitrogen use under low-nitrogen conditions. Endophytic nitrogen-fixing bacteria require a large amount of energy to fix atmospheric nitrogen. However, it is unknown which carbon source and bacteria would affect nitrogen-fixing activity in rice. Therefore, this study examined genotypic variations in the nitrogen-fixing ability of rice plant stem as affected by non-structural carbohydrates and endophytic bacterial flora in field-grown rice. In the field experiments, six varieties and 10 genotypes of rice were grown in 2017 and 2018 to compare the acetylene reduction activity (nitrogen-fixing activity) and non-structural carbohydrates (glucose, sucrose, and starch) concentration in their stems at the heading stage. For the bacterial flora analysis, two genes were amplified using a primer set of 16S rRNA and nitrogenase (NifH) gene-specific primers. Next, acetylene reduction activity was correlated with sugar concentration among genotypes in both years, suggesting that the levels of soluble sugars influenced stem nitrogen-fixing activity. Bacterial flora analysis also suggested the presence of common and genotype-specific bacterial flora in both 16S rRNA and nifH genes. Similarly, bacteria classified as rhizobia, such as Bradyrhizobium sp. (Alphaproteobacteria) and Paraburkholderia sp. (Betaproteobacteria), were highly abundant in all rice genotypes, suggesting that these bacteria make major contributions to the nitrogen fixation process in rice stems. Gammaproteobacteria were more abundant in CG14 as well, which showed the highest acetylene reduction activity and sugar concentration among genotypes and is also proposed to contribute to the higher amount of nitrogen-fixing activity.
topic bacterial flora
endophyte
nifH
nitrogen fixation
non-structural carbohydrate
rice
url https://www.frontiersin.org/articles/10.3389/fpls.2021.719259/full
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