Exploring the Potential of Methanotrophs for Plant Growth Promotion in Rice Agriculture

Rice fields are one of the important anthropogenic sources of methane emissions. Methanotrophs dwelling near the rice roots and at the oxic–anoxic interface of paddy fields can oxidize a large fraction of the generated methane and are therefore considered to be important. Nitrogen fixation in rice r...

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Main Authors: Jyoti A. Mohite, Kumal Khatri, Kajal Pardhi, Shubha S. Manvi, Rutuja Jadhav, Shilpa Rathod, Monali C. Rahalkar
Format: Article
Language:English
Published: MDPI AG 2023-09-01
Series:Methane
Subjects:
Online Access:https://www.mdpi.com/2674-0389/2/4/24
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author Jyoti A. Mohite
Kumal Khatri
Kajal Pardhi
Shubha S. Manvi
Rutuja Jadhav
Shilpa Rathod
Monali C. Rahalkar
author_facet Jyoti A. Mohite
Kumal Khatri
Kajal Pardhi
Shubha S. Manvi
Rutuja Jadhav
Shilpa Rathod
Monali C. Rahalkar
author_sort Jyoti A. Mohite
collection DOAJ
description Rice fields are one of the important anthropogenic sources of methane emissions. Methanotrophs dwelling near the rice roots and at the oxic–anoxic interface of paddy fields can oxidize a large fraction of the generated methane and are therefore considered to be important. Nitrogen fixation in rice root-associated methanotrophs is well known. Our aim in this study was to explore the potential of methanotrophs as bio-inoculants for rice and the studies were performed in pot experiments in monsoon. Ten indigenously isolated methanotrophs were used belonging to eight diverse genera of Type Ia, Type Ib, and Type II methanotrophs, including the newly described genera and/or species, <i>Methylocucumis oryzae</i> and <i>Methylolobus aquaticus</i>, as well as <i>Ca.</i> Methylobacter oryzae and <i>Ca.</i> Methylobacter coli. Additionally, two consortia (<i>Methylomonas</i> strains and <i>Methylocystis</i>-<i>Methylosinus</i> strains) were used. Nitrogen fixation pathways or <i>nifH</i> genes were detected in all of the used methanotrophs. Plant growth promotion (PGPR) was seen in terms of increased plant height and grain yield. Nine out of twelve (seven single strains and two consortia) showed positive effects on grain yield (6–38%). The highest increase in grain yield was seen after inoculation with <i>Ca.</i> Methylobacter coli (38%) followed by <i>Methylomonas</i> consortium (35%) and <i>Methylocucumis oryzae</i> (31%). <i>Methylomagnum ishizawai</i> inoculated plants showed the highest plant height. <i>Methylocucumis oryzae</i> inoculated plants showed early flowering, grain formation, and grain maturation (~17–18 days earlier). In all the pot experiments, minimal quantities of nitrogen fertilizer were used with no additional organic fertilizer inputs. The present study demonstrated the possibility of developing methanotrophs as bio-inoculants for rice agriculture, which would promote plant growth under low inputs of nitrogenous fertilizers. Although the effect of methanotrophs on methane mitigation is still under investigation, their application to reduce methane emissions from rice fields could be an added advantage.
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spelling doaj.art-c1b28974610a4b8ca150d3edf604f2b32023-12-22T14:24:55ZengMDPI AGMethane2674-03892023-09-012436137110.3390/methane2040024Exploring the Potential of Methanotrophs for Plant Growth Promotion in Rice AgricultureJyoti A. Mohite0Kumal Khatri1Kajal Pardhi2Shubha S. Manvi3Rutuja Jadhav4Shilpa Rathod5Monali C. Rahalkar6C2, MACS Agharkar Research Institute, G.G. Agarkar Road, Pune 411004, Maharashtra, IndiaC2, MACS Agharkar Research Institute, G.G. Agarkar Road, Pune 411004, Maharashtra, IndiaC2, MACS Agharkar Research Institute, G.G. Agarkar Road, Pune 411004, Maharashtra, IndiaC2, MACS Agharkar Research Institute, G.G. Agarkar Road, Pune 411004, Maharashtra, IndiaBiotechnology Department, Rajarshi Shahu Mahavidyalaya Latur, Latur 423511, Maharashtra, IndiaBiotechnology Department, Rajarshi Shahu Mahavidyalaya Latur, Latur 423511, Maharashtra, IndiaC2, MACS Agharkar Research Institute, G.G. Agarkar Road, Pune 411004, Maharashtra, IndiaRice fields are one of the important anthropogenic sources of methane emissions. Methanotrophs dwelling near the rice roots and at the oxic–anoxic interface of paddy fields can oxidize a large fraction of the generated methane and are therefore considered to be important. Nitrogen fixation in rice root-associated methanotrophs is well known. Our aim in this study was to explore the potential of methanotrophs as bio-inoculants for rice and the studies were performed in pot experiments in monsoon. Ten indigenously isolated methanotrophs were used belonging to eight diverse genera of Type Ia, Type Ib, and Type II methanotrophs, including the newly described genera and/or species, <i>Methylocucumis oryzae</i> and <i>Methylolobus aquaticus</i>, as well as <i>Ca.</i> Methylobacter oryzae and <i>Ca.</i> Methylobacter coli. Additionally, two consortia (<i>Methylomonas</i> strains and <i>Methylocystis</i>-<i>Methylosinus</i> strains) were used. Nitrogen fixation pathways or <i>nifH</i> genes were detected in all of the used methanotrophs. Plant growth promotion (PGPR) was seen in terms of increased plant height and grain yield. Nine out of twelve (seven single strains and two consortia) showed positive effects on grain yield (6–38%). The highest increase in grain yield was seen after inoculation with <i>Ca.</i> Methylobacter coli (38%) followed by <i>Methylomonas</i> consortium (35%) and <i>Methylocucumis oryzae</i> (31%). <i>Methylomagnum ishizawai</i> inoculated plants showed the highest plant height. <i>Methylocucumis oryzae</i> inoculated plants showed early flowering, grain formation, and grain maturation (~17–18 days earlier). In all the pot experiments, minimal quantities of nitrogen fertilizer were used with no additional organic fertilizer inputs. The present study demonstrated the possibility of developing methanotrophs as bio-inoculants for rice agriculture, which would promote plant growth under low inputs of nitrogenous fertilizers. Although the effect of methanotrophs on methane mitigation is still under investigation, their application to reduce methane emissions from rice fields could be an added advantage.https://www.mdpi.com/2674-0389/2/4/24methanotrophsrice agriculturebio-inoculantsplant growth promotion<i>nifH</i> geneType I methanotrophs
spellingShingle Jyoti A. Mohite
Kumal Khatri
Kajal Pardhi
Shubha S. Manvi
Rutuja Jadhav
Shilpa Rathod
Monali C. Rahalkar
Exploring the Potential of Methanotrophs for Plant Growth Promotion in Rice Agriculture
Methane
methanotrophs
rice agriculture
bio-inoculants
plant growth promotion
<i>nifH</i> gene
Type I methanotrophs
title Exploring the Potential of Methanotrophs for Plant Growth Promotion in Rice Agriculture
title_full Exploring the Potential of Methanotrophs for Plant Growth Promotion in Rice Agriculture
title_fullStr Exploring the Potential of Methanotrophs for Plant Growth Promotion in Rice Agriculture
title_full_unstemmed Exploring the Potential of Methanotrophs for Plant Growth Promotion in Rice Agriculture
title_short Exploring the Potential of Methanotrophs for Plant Growth Promotion in Rice Agriculture
title_sort exploring the potential of methanotrophs for plant growth promotion in rice agriculture
topic methanotrophs
rice agriculture
bio-inoculants
plant growth promotion
<i>nifH</i> gene
Type I methanotrophs
url https://www.mdpi.com/2674-0389/2/4/24
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