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Post-translational regulation of plasma membrane H+-ATPase is involved in the release of biological nitrification inhibitors from sorghum roots.
- Source :
- Plant & Soil; May2020, Vol. 450 Issue 1/2, p357-372, 16p, 1 Diagram, 7 Graphs
- Publication Year :
- 2020
-
Abstract
- Background: It is an integral property of sorghum (Sorghum bicolor L.) to extensively release biological nitrification inhibitors (BNIs) under NH<subscript>4</subscript><superscript>+</superscript> nutrition, in comparison to NO<subscript>3</subscript><superscript>−</superscript> nutrition. Our previous research indicated that plasma membrane (PM) H<superscript>+</superscript>-ATPase activity was stimulated by NH<subscript>4</subscript><superscript>+</superscript> and low rhizosphere pH, which in turn provided the driving force for BNIs release from sorghum roots. However, the regulatory mechanism of PM H<superscript>+</superscript>-ATPase itself in this regard is not fully elucidated. The present study thus aims at post-translational regulation of PM H<superscript>+</superscript>-ATPase via phosphorylation in response to NH<subscript>4</subscript><superscript>+</superscript> nutrition and its functional link to the release of BNIs from sorghum roots. Methods: A hydroponic system is used to grow sorghum with 1 mM NH<subscript>4</subscript><superscript>+</superscript> or NO<subscript>3</subscript><superscript>−</superscript> as N source at pH 3.0 or pH 7.0 in root medium for the analysis of PM H<superscript>+</superscript>-ATPase and BNIs release. The effect of NH<subscript>4</subscript><superscript>+</superscript> on the regulation of PM H<superscript>+</superscript>-ATPase was further evaluated by the treatment of NO<subscript>3</subscript><superscript>−</superscript>cultivated sorghum roots with different NH<subscript>4</subscript><superscript>+</superscript> concentrations (0.1~1 mM). In addition, fusicoccin (a stimulator of PM H<superscript>+</superscript>-ATPase) and vanadate (an inhibitor of PM H<superscript>+</superscript>-ATPase) were added to check the effect of PM H<superscript>+</superscript>-ATPase phosphorylation on BNIs release. Further, methionine sulphoximine (MSX), which inhibits glutamine synthetase, is used to analyze the effect of ammonium transport/assimilation process on the PM H<superscript>+</superscript>-ATPase and BNIs release. Microsomal membrane protein isolated from these roots was used for the test of PM H<superscript>+</superscript>-ATPase phosphorylation level by western blot technique. Meanwhile, the root exudates were collected for the analysis of BNIs. Results: Higher amount of PM H<superscript>+</superscript>-ATPase protein with higher phosphorylation level were detected in sorghum roots in response to NH<subscript>4</subscript><superscript>+</superscript> and low rhizosphere pH, as compared to NO<subscript>3</subscript><superscript>−</superscript> and high pH. Further, PM H<superscript>+</superscript>-ATPase protein amount and phosporylation level were dependent on the local supplement of NH<subscript>4</subscript><superscript>+</superscript> (from 0.1 ~ 1 mM) to roots. Nevertheless, the enhanced posphorylation level under all of these treatments was significantly higher than the enhanced protein level of PM H<superscript>+</superscript> ATPase. Unlike protein level, phosphorylation level is closely correlated to the release of BNIs from sorghum roots. In addition, phosphorylation level of PM H<superscript>+</superscript>-ATPase adjusted by fusicoccin or vanadate directly affected the release of BNIs, irrespective of the protein level. In addition, ammonium assimilation inhibitor MSX caused decreased phosphorylation level of PM H<superscript>+</superscript>-ATPase without affecting the protein level, meanwhile inhibited the release of BNIs from sorghum roots. Conclusion: Our research suggests that phosphorylation of PM H<superscript>+</superscript>-ATPase is one of the important regulation mechanisms involved in the release of BNIs from sorghum roots. NH<subscript>4</subscript><superscript>+</superscript> stimulated PM H<superscript>+</superscript>-ATPase phosphorylation via excessive H<superscript>+</superscript> generated by NH<subscript>4</subscript><superscript>+</superscript> assimilation in cytoplasm. The up regulation of PM H<superscript>+</superscript>-ATPase at post-translational level thus activated the H<superscript>+</superscript> pumping activity to provide the driving force for BNIs release. A new hypothesis is proposed to elucidate the interplay of these functionally inter-linked processes involving ammonium-uptake, −assimilation, and H<superscript>+</superscript>-pumps activation in PM on the release of BNIs from sorghum roots. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 0032079X
- Volume :
- 450
- Issue :
- 1/2
- Database :
- Complementary Index
- Journal :
- Plant & Soil
- Publication Type :
- Academic Journal
- Accession number :
- 143855327
- Full Text :
- https://doi.org/10.1007/s11104-020-04511-6