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The microbe-secreted isopeptide poly- γ -glutamic acid induces stress tolerance in Brassica napus L. seedlings by activating crosstalk between H 2 O 2 and Ca 2+

View Article: PubMed Central - PubMed

ABSTRACT

Poly-γ-glutamic acid (γ-PGA) is a microbe-secreted isopeptide that has been shown to promote growth and enhance stress tolerance in crops. However, its site of action and downstream signaling pathways are still unknown. In this study, we investigated γ-PGA-induced tolerance to salt and cold stresses in Brassica napus L. seedlings. Fluorescent labeling of γ-PGA was used to locate the site of its activity in root protoplasts. The relationship between γ-PGA-induced stress tolerance and two signal molecules, H2O2 and Ca2+, as well as the γ-PGA-elicited signaling pathway at the whole plant level, were explored. Fluorescent labeling showed that γ-PGA did not enter the cytoplasm but instead attached to the surface of root protoplasm. Here, it triggered a burst of H2O2 in roots by enhancing the transcription of RbohD and RbohF, and the elicited H2O2 further activated an influx of Ca2+ into root cells. Ca2+ signaling was transmitted via the stem from roots to leaves, where it elicited a fresh burst of H2O2, thus promoting plant growth and enhancing stress tolerance. On the basis of these observation, we propose that γ-PGA mediates stress tolerance in Brassica napus seedlings by activating an H2O2 burst and subsequent crosstalk between H2O2 and Ca2+ signaling.

No MeSH data available.


Proposed signaling pathways in crops elicited by treatment with poly-γ-glutamic acid (γ-PGA).
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f10: Proposed signaling pathways in crops elicited by treatment with poly-γ-glutamic acid (γ-PGA).

Mentions: In conclusion, in the present study, we investigated the site of action of γ-PGA in rape seedling root cells, and identified possible downstream signaling pathways that regulate stress tolerance. On the basis of the results of this study, we propose the following signaling pathway in rape seedlings in response to γ-PGA (Fig. 10): γ-PGA does not enter the cytoplasm but instead attaches to the surface of root cell protoplasts; an H2O2 burst is elicited within the root cells by enhancing the transcription of RbohD and Rboh F; H2O2 then activates Ca2+ permeability channels, leading to an influx of Ca2+ in root cells; Ca2+ signaling is transmitted from roots to leaves via the stem and a new H2O2 burst is elicited in the leaves, which contributes to plant growth and enhanced stress tolerance. Accordingly, γ-PGA mediates stress tolerance in Brassica napus seedlings by activating an H2O2 burst and subsequent cross-talk between H2O2 and Ca2+ signaling.


The microbe-secreted isopeptide poly- γ -glutamic acid induces stress tolerance in Brassica napus L. seedlings by activating crosstalk between H 2 O 2 and Ca 2+
Proposed signaling pathways in crops elicited by treatment with poly-γ-glutamic acid (γ-PGA).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5304171&req=5

f10: Proposed signaling pathways in crops elicited by treatment with poly-γ-glutamic acid (γ-PGA).
Mentions: In conclusion, in the present study, we investigated the site of action of γ-PGA in rape seedling root cells, and identified possible downstream signaling pathways that regulate stress tolerance. On the basis of the results of this study, we propose the following signaling pathway in rape seedlings in response to γ-PGA (Fig. 10): γ-PGA does not enter the cytoplasm but instead attaches to the surface of root cell protoplasts; an H2O2 burst is elicited within the root cells by enhancing the transcription of RbohD and Rboh F; H2O2 then activates Ca2+ permeability channels, leading to an influx of Ca2+ in root cells; Ca2+ signaling is transmitted from roots to leaves via the stem and a new H2O2 burst is elicited in the leaves, which contributes to plant growth and enhanced stress tolerance. Accordingly, γ-PGA mediates stress tolerance in Brassica napus seedlings by activating an H2O2 burst and subsequent cross-talk between H2O2 and Ca2+ signaling.

View Article: PubMed Central - PubMed

ABSTRACT

Poly-γ-glutamic acid (γ-PGA) is a microbe-secreted isopeptide that has been shown to promote growth and enhance stress tolerance in crops. However, its site of action and downstream signaling pathways are still unknown. In this study, we investigated γ-PGA-induced tolerance to salt and cold stresses in Brassica napus L. seedlings. Fluorescent labeling of γ-PGA was used to locate the site of its activity in root protoplasts. The relationship between γ-PGA-induced stress tolerance and two signal molecules, H2O2 and Ca2+, as well as the γ-PGA-elicited signaling pathway at the whole plant level, were explored. Fluorescent labeling showed that γ-PGA did not enter the cytoplasm but instead attached to the surface of root protoplasm. Here, it triggered a burst of H2O2 in roots by enhancing the transcription of RbohD and RbohF, and the elicited H2O2 further activated an influx of Ca2+ into root cells. Ca2+ signaling was transmitted via the stem from roots to leaves, where it elicited a fresh burst of H2O2, thus promoting plant growth and enhancing stress tolerance. On the basis of these observation, we propose that γ-PGA mediates stress tolerance in Brassica napus seedlings by activating an H2O2 burst and subsequent crosstalk between H2O2 and Ca2+ signaling.

No MeSH data available.