Priming winter wheat seeds with the bacterial quorum sensing signal N-hexanoyl-L-homoserine lactone (C6-HSL) shows potential to improve plant growth and seed yield

RESEARCH ARTICLE Priming winter wheat seeds with the bacterial quorum sensing signal N-hexanoyl-Lhomoserine lactone (C6-HSL) shows potential to improve plant growth and seed yield Olena V. Moshynets ID1☯*, Lidia M. Babenko2☯, Sergiy P. Rogalsky3, Olga S. Iungin4, Jessica Foster5, Iryna V. Kosakivska2, Geert Potters6,7, Andrew J. Spiers5* a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 1 Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kiev, Ukraine, 2 M. G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine, Kiev, Ukraine, 3 V.P. Kukhar Institute of Bioorganic Chemistry and Petrochemistry, National Academy of Sciences of Ukraine, Kiev, Ukraine, 4 D.K. Zabolotny Institute of Microbiology and Virology, National Academy of Sciences of Ukraine, Kiev, Ukraine, 5 School of Science, Engineering and Technology, Abertay University, Dundee, United Kingdom, 6 Antwerp Maritime Academy, Antwerp, Belgium, 7 Department of Bioscience Engineering, University of Antwerp, Antwerp, Belgium ☯ These authors contributed equally to this work. * (OM); (AS) OPEN ACCESS Citation: Moshynets OV, Babenko LM, Rogalsky SP, Iungin OS, Foster J, Kosakivska IV, et al. (2019) Priming winter wheat seeds with the bacterial quorum sensing signal N-hexanoyl-Lhomoserine lactone (C6-HSL) shows potential to improve plant growth and seed yield. PLoS ONE 14 (2): e0209460. https://doi.org/10.1371/journal. pone.0209460 Editor: Ricardo Aroca, Estacion Experimental del Zaidin, SPAIN Received: November 29, 2018 Accepted: February 7, 2019 Published: February 25, 2019 Copyright: © 2019 Moshynets et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the manuscript. Funding: The project was partially supported by a grant to L.M. Babenko and O.V. Moshynets (0115U004178; Development of wheat priming biotechnology based on N-Acyl Homoserine Lactones for increasing resistance and productivity, 2015-2019) provided under the National Multidisciplinary NASU Research Program Abstract Several model plants are known to respond to bacterial quorum sensing molecules with altered root growth and gene expression patterns and induced resistance to plant pathogens. These compounds may represent novel elicitors that could be applied as seed primers to enhance cereal crop resistance to pathogens and abiotic stress and to improve yields. We investigated whether the acyl-homoserine lactone N-hexanoyl-L-homoserine lactone (C6-HSL) impacted winter wheat (Triticum aestivum L.) seed germination, plant development and productivity, using two Ukrainian varieties, Volodarka and Yatran 60, in both in vitro experiments and field trials. In vitro germination experiments indicated that C6-HSL seed priming had a small but significant positive impact on germination levels (1.2x increase, p < 0.0001), coleoptile and radicle development (1.4x increase, p < 0.0001). Field trials over two growing seasons (2015–16 and 2016–17) also demonstrated significant improvements in biomass at the tillering stage (1.4x increase, p < 0.0001), and crop structure and productivity at maturity including grain yield (1.4–1.5x increase, p < 0.0007) and quality (1.3x increase in good grain, p < 0.0001). In some cases variety effects were observed (p � 0.05) suggesting that the effect of C6-HSL seed priming might depend on plant genetics, and some benefits of priming were also evident in F1 plants grown from seeds collected the previous season (p � 0.05). These field-scale findings suggest that bacterial acyl-homoserine lactones such as C6-HSL could be used to improve cereal crop growth and yield and reduce reliance on fungicides and fertilisers to combat pathogens and stress. PLOS ONE | https://doi.org/10.1371/journal.pone.0209460 February 25, 2019 1 / 17 Priming winter wheat seeds with N-hexanoyl-L-homoserine lactone (C6-HSL) “Molecular and Cellular Biotechnology for Medicine, Industry and Agrarian Sciences”. Further internal support to O.V. Moshynets and A.J. Spiers was provided by IMBG and Abertay University. There was no additional external funding received for this study. Competing interests: The authors have declared that no competing interests exist. Introduction Wheat is one of the most important food staples and export commodities in Ukraine with ~95% of the harvest coming from winter wheat crops [1]. Winter wheat represents ~95% of the annual crop with the remaining 5% planted as spring wheat [2]. It is typically sown in autumn (September-October) and harvested in mid-summer (July) of the following year, however, weather conditions severely affect the quality of the crop, and frequent changes during the growing season makes it more susceptible to bacterial and fungal pathogens than spring wheat which is grown from April to August. While there are a number of intensive agricultural technologies to improve crop yield and control pathogens, the economics of wheat production is dominated by the need to keep inputs beyond pre-plant bactericide and fungicide treatment and fertilization low to be economical [3]. Therefore, there is a need to augment existing production practices with economical, yet effective seed treatments to increase crop yield and resistance to pathogens. The large-scale use of agricultural bactericides and fungicides, their persistence and impact on the wider environment is of increasing concern, with over 284,411 tonnes used worldwide in 2015 [4]. Their use can be reduced by using plant growth-promoting bacterial inoculants as well as bacterially-derived plant growth regulators to treat seeds and seedlings [5–7]. Such ‘green’ technology is becoming more popular, and in some cases, natural phyto-stimulators provide a more lasting impact on crop stress tolerance and increase productivity without undesirable environmental effects [8]. One of the most effective technologies to increase crop resistance to biotic and abiotic stressors is seed priming which increases germination vigour and activates plant defence mechanisms early in plant development through induced resistance [9,10]. Plant growth can be further supported by bacterial inocula which can facilitate mineral up-take and reduce pathogens through biological competition as well as stimulate the plant defence system [11,12]. Plants are also known to respond to bacterial quorum sensing signal molecules used by bacteria to regulate gene expression and coordinate social activities [9–10, 13–15]. For example, the legume Medicago truncatula responds to nanomolar concentrations of acyl-homoserine lactones (AHLs) produced by its symbiont Sinorhizobium meliloti and the pathogen Pseudomonas aeruginosa with specific and extensive changes in root gene expression and protein accumulation [ (...truncated)