Bacillus megaterium GXU087 secretes indole - 3 - lactic acid to promote soybean growth and nodulation

Bacillus species are recognized as plant growth-promoting bacteria (PGPB), yet the mechanisms behind their crop growth promotion remain elusive. This study is designed to explore the plant growth-promoting (PGP) effects of Bacillus megaterium GXU087 on soybeans and to uncover the underlying mechanis...

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Main Authors: Jingsi Qiu, Xiao’ou Meng, Jingdong Li, Tengfei Zhang, Siying Qin, Yuanfu Li, Huihua Tan
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-03-01
Series:Frontiers in Plant Science
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Online Access:https://www.frontiersin.org/articles/10.3389/fpls.2025.1560346/full
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author Jingsi Qiu
Xiao’ou Meng
Jingdong Li
Tengfei Zhang
Siying Qin
Yuanfu Li
Huihua Tan
author_facet Jingsi Qiu
Xiao’ou Meng
Jingdong Li
Tengfei Zhang
Siying Qin
Yuanfu Li
Huihua Tan
author_sort Jingsi Qiu
collection DOAJ
description Bacillus species are recognized as plant growth-promoting bacteria (PGPB), yet the mechanisms behind their crop growth promotion remain elusive. This study is designed to explore the plant growth-promoting (PGP) effects of Bacillus megaterium GXU087 on soybeans and to uncover the underlying mechanism. In vitro, GXU087 exhibited various PGP traits, including phosphate solubilization, nitrogen fixation, production of exopolysaccharide, and biofilm formation. Pot experiments indicated that GXU087 significantly enhanced soybean growth, leading to a remarkable increase in fresh weight (p < 0.05). Additionally, the nodulation parameters of soybeans were improved. Specifically, a 10% concentration of the extracellular extracts from GXU087 exerted a significant promotion on nodulation, with both nodule number and fresh weight parameters increasing significantly (p < 0.05). UPLC-MS analysis verified that GXU087 secreted indole-3-lactic acid (ILA) at a concentration of 232.7 ng/mL. Pot assays further demonstrated that this ILA effectively promoted soybean growth and nodulation within a concentration range of 0.1-10 mg/L. However, exogenous application of ILA did not stimulate rhizobia reproduction, suggesting that bacterial ILA does not promote nodulation by enhancing rhizobia growth. Notably, this is the first report of B. megaterium secreting ILA as a growth and nodulation promoter in soybeans. Our findings offer new insights into the mechanism of B. megaterium action and contribute to the understanding of microbe-induced growth promotion in crops.
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series Frontiers in Plant Science
spelling doaj-art-72e49d7bf89c4902be1430b19010a71f2025-08-20T03:41:52ZengFrontiers Media S.A.Frontiers in Plant Science1664-462X2025-03-011610.3389/fpls.2025.15603461560346Bacillus megaterium GXU087 secretes indole - 3 - lactic acid to promote soybean growth and nodulationJingsi QiuXiao’ou MengJingdong LiTengfei ZhangSiying QinYuanfu LiHuihua TanBacillus species are recognized as plant growth-promoting bacteria (PGPB), yet the mechanisms behind their crop growth promotion remain elusive. This study is designed to explore the plant growth-promoting (PGP) effects of Bacillus megaterium GXU087 on soybeans and to uncover the underlying mechanism. In vitro, GXU087 exhibited various PGP traits, including phosphate solubilization, nitrogen fixation, production of exopolysaccharide, and biofilm formation. Pot experiments indicated that GXU087 significantly enhanced soybean growth, leading to a remarkable increase in fresh weight (p < 0.05). Additionally, the nodulation parameters of soybeans were improved. Specifically, a 10% concentration of the extracellular extracts from GXU087 exerted a significant promotion on nodulation, with both nodule number and fresh weight parameters increasing significantly (p < 0.05). UPLC-MS analysis verified that GXU087 secreted indole-3-lactic acid (ILA) at a concentration of 232.7 ng/mL. Pot assays further demonstrated that this ILA effectively promoted soybean growth and nodulation within a concentration range of 0.1-10 mg/L. However, exogenous application of ILA did not stimulate rhizobia reproduction, suggesting that bacterial ILA does not promote nodulation by enhancing rhizobia growth. Notably, this is the first report of B. megaterium secreting ILA as a growth and nodulation promoter in soybeans. Our findings offer new insights into the mechanism of B. megaterium action and contribute to the understanding of microbe-induced growth promotion in crops.https://www.frontiersin.org/articles/10.3389/fpls.2025.1560346/fullsoybeanBacillus megateriumindole-3-lactic acidPGPBnodulation
spellingShingle Jingsi Qiu
Xiao’ou Meng
Jingdong Li
Tengfei Zhang
Siying Qin
Yuanfu Li
Huihua Tan
Bacillus megaterium GXU087 secretes indole - 3 - lactic acid to promote soybean growth and nodulation
Frontiers in Plant Science
soybean
Bacillus megaterium
indole-3-lactic acid
PGPB
nodulation
title Bacillus megaterium GXU087 secretes indole - 3 - lactic acid to promote soybean growth and nodulation
title_full Bacillus megaterium GXU087 secretes indole - 3 - lactic acid to promote soybean growth and nodulation
title_fullStr Bacillus megaterium GXU087 secretes indole - 3 - lactic acid to promote soybean growth and nodulation
title_full_unstemmed Bacillus megaterium GXU087 secretes indole - 3 - lactic acid to promote soybean growth and nodulation
title_short Bacillus megaterium GXU087 secretes indole - 3 - lactic acid to promote soybean growth and nodulation
title_sort bacillus megaterium gxu087 secretes indole 3 lactic acid to promote soybean growth and nodulation
topic soybean
Bacillus megaterium
indole-3-lactic acid
PGPB
nodulation
url https://www.frontiersin.org/articles/10.3389/fpls.2025.1560346/full
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