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Bioactive Constituents, Metabolites, and Functions
ACC Deaminase from Lysobacter gummosus OH17 Can Promote Root Growth in Oryza sativa Nipponbare Plants Pedro Laborda, Jun Ling, Xian Chen, and Fengquan Liu J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.8b00063 • Publication Date (Web): 26 Mar 2018 Downloaded from http://pubs.acs.org on March 26, 2018
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Journal of Agricultural and Food Chemistry
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ACC Deaminase from Lysobacter gummosus OH17 Can Promote
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Root Growth in Oryza sativa Nipponbare Plants
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Pedro Laborda,†,‡ Jun Ling,†,‡ Xian Chen,† and Fengquan Liu†,*
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†
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Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of
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Ministry of Science and Technology, Nanjing 210014, People´s Republic of China
Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key
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‡
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*
Both authors contributed equally to this work.
Corresponding author: Prof. Fengquan Liu;
[email protected].
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ABSTRACT
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Although Lysobacter species are a remarkable source of natural compounds with
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antibacterial and antifungal activities, the ability of these bacteria to produce plant
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growth promoters remained practically unknown. In this work, ethylene precursor
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1-aminocyclopropane-1-carboxylic acid (ACC) has been isolated from the secretions
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of Lysobacter gummosus OH17 indicating the presence of an ACC deaminase which
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was shown to be encoded in the gene peg_1256. Recombinant enzyme could not only
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deaminate ACC to provide 2-oxobutanoic acid but also catalyze the amination of
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2-oxobutanoic acid demonstrating, for the first time, that ACC deaminases can
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produce ACC. After treatment of rice Oryza sativa Nipponbare plants with OH17
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ACC deaminase, the ethylene production levels were 44% higher in comparison with
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the control experiments allowing significant improvements in root, 10%, and stem,
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14%, growth.
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Key words: ACC deaminase, Lysobacter, Oryza sativa Nipponbare, plant growth, rice
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growth promoter.
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Journal of Agricultural and Food Chemistry
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INTRODUCTION
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Ethephon is the most frequent plant growth regulator and has contributed in a
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significant manner to spectacular improvements in crop productivity.1-4 For example,
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ethephon is commonly used to promote the growth of wheat, coffee, tobacco, cotton,
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vine or rice, to mature fruits or to initiate the reproductive development of pineapple.
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However, the toxicity of this agent inducing the synthesis of peroxides and, then,
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enhancing the ozone damage in plants as well as the demonstrated cytotoxicity in
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animals has stimulated a global concern and the regulation in several countries.5-10 In
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this
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1-aminocyclopropane-1-carboxylate (ACC) deaminases, has been postulated as one of
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the most suitable ways to overcome above mentioned problems.11,12 ACC is an
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intermediate included in the methionine cycle of plant roots which is obtained
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throughout
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S-adenosyl-L-methionine, and can be transformed to plant growth hormone ethylene
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in the presence of ACC-oxidase (Scheme 1A).13 ACC deaminases have been found in
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several soil bacteria.14-17 ACC deaminases are capable of catalyzing the deamination
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of ACC to provide 2-oxobutanoic acid (Scheme 1B). It has been reported that bacteria
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which encode ACC deaminases are able to promote plant growth in plants when the
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bacteria interact with the plant root.18-22
sense,
the
ACC
use
of
environmental-friendly
synthase-catalyzed
hydrolysis
alternatives,
and
including
oxidation
of
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Lysobacter is a soil bacterium which has been shown to be an interesting source of
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active secondary metabolites.23 For example, antifungal metabolites “heat stable
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antifungal factor” (HSAF) and p-aminobenzoic acid were found in Lysobacter
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enzymogenes OH11 and Lysobacter antibioticus OH13, respectively, or a new family
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of cyclic lipodepsipeptides, WAP-8294A, with potent activity against gram-positive
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bacteria was discovered in both Lysobacter sp. 8294 and Lysobacter enzymogenes 3
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OH11.24-27 In spite of the relevant advances in the discovery of new biocontrol agents
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with antibacterial and antifungal activities for the treatment of plant diseases, the
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ability of these bacteria to produce plant growth promoters remained practically
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unknown. In this field, Fürnkranz and coworkers reported in 2012 an increase in
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germination rates as well as in mean values of harvest yields of Styrian oil pumpkins
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after treatment of the pumpkin seeds with Lysobacter gummosus L101.28 Although
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this important contribution suggested the presence of plant growth regulators in
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Lysobacter species apart from antibacterial and antifungal metabolites, no plant
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regulator was reported until the date. For this reason, we decided to identify the active
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agent responsible for this function in Lysobacter gummosus to demonstrate that
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Lysobacter species can be an interesting tool for plant growth promotion. In this work,
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ACC has been isolated from Lysobacter gummosus OH17 secretions indicating OH17
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encodes
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1-aminocyclopropane-1-carboxylate deaminase OH17 has been identified. Finally, the
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effect of OH17 ACC deaminase in Oryza sativa Nipponbare metabolism and growth
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has been studied.
an
ACC
deaminase.
The
gene
encoding
the
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MATERIALS AND METHODS
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General. All reagents and chemicals were used as received from commercial
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suppliers without further purification or modification. NMR spectra were registered
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on a Bruker AV-400 instrument using the deuterated DMSO residual solvent signal as
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the internal standard. ESI mass spectrum was obtained on an AB (QTRAP 6500) mass
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spectrometer. 4
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Journal of Agricultural and Food Chemistry
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Data analysis. The statistical analyses were performed using SPSS (Statistical
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Package, Version 20.0). The variables were subjected to student T-test and were tested
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for significance at P
