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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+

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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.


Effects of H2O2 elicited by poly-γ-glutamic acid (γ-PGA) on (A) total anti-oxidative capacity (T-AOC) and (B) proline content.
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f4: Effects of H2O2 elicited by poly-γ-glutamic acid (γ-PGA) on (A) total anti-oxidative capacity (T-AOC) and (B) proline content.

Mentions: In this study, we used the T-AOC and proline content as indicators of stress tolerance in rape seedlings. As shown in Fig. 4A, compared with the control, γ-PGA significantly increased the T-AOC of rape seedling leaves. However, diphenylene iodonium (DPI: an inhibitor of H2O2 production) almost completely inhibited this increase in T-AOC caused by γ-PGA. Similarly, the proline content in leaves was also significantly increased by γ-PGA, and this increase was also inhibited by DPI (Fig. 4B).


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+
Effects of H2O2 elicited by poly-γ-glutamic acid (γ-PGA) on (A) total anti-oxidative capacity (T-AOC) and (B) proline content.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: Effects of H2O2 elicited by poly-γ-glutamic acid (γ-PGA) on (A) total anti-oxidative capacity (T-AOC) and (B) proline content.
Mentions: In this study, we used the T-AOC and proline content as indicators of stress tolerance in rape seedlings. As shown in Fig. 4A, compared with the control, γ-PGA significantly increased the T-AOC of rape seedling leaves. However, diphenylene iodonium (DPI: an inhibitor of H2O2 production) almost completely inhibited this increase in T-AOC caused by γ-PGA. Similarly, the proline content in leaves was also significantly increased by γ-PGA, and this increase was also inhibited by DPI (Fig. 4B).

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.