Gagné-Bourque François, Bertrand Annick, Claessens Annie, Aliferis Konstantinos A, Jabaji Suha
Department of Plant Science, Faculty of Agricultural and Environmental Sciences, Macdonald Campus of McGill University, Sainte-Anne-de-Bellevue QC, Canada.
Quebec Research and Development Center, Agriculture and Agri-Food Canada, Québec City QC, Canada.
Front Plant Sci. 2016 May 3;7:584. doi: 10.3389/fpls.2016.00584. eCollection 2016.
Drought is a major limiting factor of crop productivity worldwide and its incidence is predicted to increase under climate change. Drought adaptation of cool-season grasses is thus a major challenge to secure the agricultural productivity under current and future climate conditions. Endophytes are non-pathogenic plant-associated bacteria that can play an important role in conferring resistance and improving plant tolerance to drought. In this study, the effect of inoculation of the bacterial endophyte Bacillus subtilis strain B26 on growth, water status, photosynthetic activity and metabolism of timothy (Phleum pratense L.) subjected to drought stress was investigated under controlled conditions. Under both drought-stress and non-stressed conditions, strain B26 successfully colonized the internal tissues of timothy and had a positive impact on plant growth. Exposure of inoculated plant to a 8-week drought-stress led to significant increase in shoot and root biomass by 26.6 and 63.8%, and in photosynthesis and stomatal conductance by 55.2 and 214.9% respectively, compared to non-inoculated plants grown under similar conditions. There was a significant effect of the endophyte on plant metabolism; higher levels of several sugars, notably sucrose and fructans and an increase of key amino acids such as, asparagine, glutamic acid and glutamine were recorded in shoots and roots of colonized plants compared to non-colonized ones. The accumulation of the non-protein amino acid GABA in shoots of stressed plants and in roots of stressed and unstressed plants was increased in the presence of the endophyte. Taken together, our results indicate that B. subtilis B26 improves timothy growth under drought stress through the modification of osmolyte accumulation in roots and shoots. These results will contribute to the development of a microbial agent to improve the yield of grass species including forage crops and cereals exposed to environmental stresses.
干旱是全球作物生产力的主要限制因素，预计在气候变化下其发生频率将会增加。因此，冷季型草的干旱适应性是确保当前和未来气候条件下农业生产力的一项重大挑战。内生菌是与植物共生的非致病细菌，在赋予植物抗性和提高植物耐旱性方面可发挥重要作用。在本研究中，在可控条件下研究了接种细菌内生枯草芽孢杆菌菌株B26对遭受干旱胁迫的猫尾草（Phleum pratense L.）生长、水分状况、光合活性和代谢的影响。在干旱胁迫和非胁迫条件下，菌株B26均成功定殖于猫尾草的内部组织，并对植物生长产生积极影响。与在相似条件下生长的未接种植物相比，接种植物经8周干旱胁迫后，地上部和根部生物量分别显著增加了26.6%和63.8%，光合作用和气孔导度分别显著增加了55.2%和214.9%。内生菌对植物代谢有显著影响；与未定殖植物相比，定殖植物地上部和根部中几种糖类（尤其是蔗糖和果聚糖）水平更高，关键氨基酸如天冬酰胺、谷氨酸和谷氨酰胺含量增加。在有内生菌存在的情况下，胁迫植物地上部以及胁迫和非胁迫植物根部中非蛋白质氨基酸GABA的积累量增加。综上所述，我们的结果表明，枯草芽孢杆菌B26通过改变根和地上部渗透调节物质的积累来促进干旱胁迫下猫尾草的生长。这些结果将有助于开发一种微生物制剂，以提高包括饲料作物和谷类作物在内的禾本科植物在环境胁迫下的产量。
