TY - JOUR

T1 - Influence of rhizobacterial volatiles on the root system architecture and the production and allocation of biomass in the model grass Brachypodium distachyon (L.) P. Beauv

AU - Delaplace, Pierre

AU - Delory, Benjamin M

AU - Baudson, Caroline

AU - Mendaluk-Saunier de Cazenave, Magdalena

AU - Spaepen, Stijn

AU - Varin, Sébastien

AU - Brostaux, Yves

AU - du Jardin, Patrick

N1 - Funding Information: The authors thank Paul Paré (Texas Tech University, Lubbock, TX, USA), Richard Sibout (Institut National de la Recherche Agronomique, Versailles, France) and Micheline Vandenbol and Marc Ongena (Gembloux Agro-Bio Tech, Gembloux, Belgium) for their fruitful discussions. The authors also thank Adeline Blondiaux for her excellent technical assistance in setting up the in vitro co-cultivation system and producing the analysed dataset. We also thank Gerry Cambier for editing the English composition of the article. This work was financially supported by the Belgian Fonds de la Recherche Scientifique - FNRS (FRFC project 2.4.591.10.F and post-doctoral grant CTP 1808458). Delory B.M. (Research Fellow) is financially supported by the Belgian National Fund for Scientific Research (F.R.S.-FNRS). Publisher Copyright: © 2015 Delaplace et al.

PY - 2015/8/12

Y1 - 2015/8/12

N2 - BACKGROUND: Plant growth-promoting rhizobacteria are increasingly being seen as a way of complementing conventional inputs in agricultural systems. The effects on their host plants are diverse and include volatile-mediated growth enhancement. This study sought to assess the effects of bacterial volatiles on the biomass production and root system architecture of the model grass Brachypodium distachyon (L.) Beauv.RESULTS: An in vitro experiment allowing plant-bacteria interaction throughout the gaseous phase without any physical contact was used to screen 19 bacterial strains for their growth-promotion ability over a 10-day co-cultivation period. Five groups of bacteria were defined and characterised based on their combined influence on biomass production and root system architecture. The observed effects ranged from unchanged to greatly increased biomass production coupled with increased root length and branching. Primary root length was increased only by the volatile compounds emitted by Enterobacter cloacae JM22 and Bacillus pumilus T4. Overall, the most significant results were obtained with Bacillus subtilis GB03, which induced an 81 % increase in total biomass, as well as enhancing total root length, total secondary root length and total adventitious root length by 88.5, 201.5 and 474.5 %, respectively.CONCLUSIONS: This study is the first report on bacterial volatile-mediated growth promotion of a grass plant. Contrasting modulations of biomass production coupled with changes in root system architecture were observed. Most of the strains that increased total plant biomass also modulated adventitious root growth. Under our screening conditions, total biomass production was strongly correlated with the length and branching of the root system components, except for primary root length. An analysis of the emission kinetics of the bacterial volatile compounds is being undertaken and should lead to the identification of the compounds responsible for the observed growth-promotion effects. Within the context of the inherent characteristics of our in vitro system, this paper identifies the next critical experimental steps and discusses them from both a fundamental and an applied perspective.

AB - BACKGROUND: Plant growth-promoting rhizobacteria are increasingly being seen as a way of complementing conventional inputs in agricultural systems. The effects on their host plants are diverse and include volatile-mediated growth enhancement. This study sought to assess the effects of bacterial volatiles on the biomass production and root system architecture of the model grass Brachypodium distachyon (L.) Beauv.RESULTS: An in vitro experiment allowing plant-bacteria interaction throughout the gaseous phase without any physical contact was used to screen 19 bacterial strains for their growth-promotion ability over a 10-day co-cultivation period. Five groups of bacteria were defined and characterised based on their combined influence on biomass production and root system architecture. The observed effects ranged from unchanged to greatly increased biomass production coupled with increased root length and branching. Primary root length was increased only by the volatile compounds emitted by Enterobacter cloacae JM22 and Bacillus pumilus T4. Overall, the most significant results were obtained with Bacillus subtilis GB03, which induced an 81 % increase in total biomass, as well as enhancing total root length, total secondary root length and total adventitious root length by 88.5, 201.5 and 474.5 %, respectively.CONCLUSIONS: This study is the first report on bacterial volatile-mediated growth promotion of a grass plant. Contrasting modulations of biomass production coupled with changes in root system architecture were observed. Most of the strains that increased total plant biomass also modulated adventitious root growth. Under our screening conditions, total biomass production was strongly correlated with the length and branching of the root system components, except for primary root length. An analysis of the emission kinetics of the bacterial volatile compounds is being undertaken and should lead to the identification of the compounds responsible for the observed growth-promotion effects. Within the context of the inherent characteristics of our in vitro system, this paper identifies the next critical experimental steps and discusses them from both a fundamental and an applied perspective.

KW - Biology

KW - Chemistry

KW - Ecosystems Research

KW - Sustainability Science

UR - http://www.scopus.com/inward/record.url?scp=84938838585&partnerID=8YFLogxK

U2 - 10.1186/s12870-015-0585-3

DO - 10.1186/s12870-015-0585-3

M3 - Journal articles

C2 - 26264238

VL - 15

JO - BMC Plant Biology

JF - BMC Plant Biology

SN - 1471-2229

IS - 1

M1 - 195

ER -