Plant-Microbe Interactions Laboratory, School of Agriculture and Food Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia; School of Pharmacy, The University of Queensland, Pharmacy Australia Centre of Excellence (PACE), Woolloongabba, Queensland 4102, Australia.
Centre for Horticultural Science, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Ecosciences Precinct, GPO Box 267, Queensland 4001, Australia.
Sci Total Environ. 2019 Nov 20;692:267-280. doi: 10.1016/j.scitotenv.2019.07.061. Epub 2019 Jul 5.
Biotic interactions through diffusible and volatile organic compounds (VOCs) are frequent in nature. Soil bacteria are well-known producers of a wide range of volatile compounds (both organic and inorganic) with various biologically relevant activities. Since the last decade, they have been identified as natural biocontrol agents. Volatiles are airborne chemicals, which when released by bacteria, can trigger plant responses such as defence and growth promotion. In this study, we tested whether diffusible and volatile organic compounds (VOCs) produced by soil bacterial isolates exert anti-oomycete and plant growth-promoting effects. We also investigated the effects of inoculation with VOC-producing bacteria on the growth and development of Capsicum annuum and Arabidopsis thaliana seedlings. Our results demonstrate that organic VOCs emitted by bacterial antagonists negatively influence mycelial growth of the soil-borne phytopathogenic oomycete Phytophthora capsici by 35% in vitro. The bacteria showed plant growth promoting effects by stimulating biomass production, primary root growth and root hair development. Additionally, we provide evidence to suggest that these activities were deployed by the emission of either diffusible organic compounds or VOCs. Bacterial VOC profiles were obtained through solid phase microextraction (SPME) and analysis by gas chromatography coupled with mass spectrometry (GC-MS). This elucidated the main volatiles emitted by the isolates, which covered a wide range of aldehydes, alcohols, esters, carboxylic acids, and ketones. Collectively, twenty-five VOCs were identified to be produced by three bacteria; some being species-specific. Our data show that bacterial volatiles inhibits P. capsici in vitro and modulate both plant growth promotion and root system development. These results confirm the significance of soil bacteria and highlights that ways of harnessing them to improve plant growth, and as a biocontrol agent for soil-borne oomycetes through their volatile emissions deserve further investigation.
生物之间通过可扩散和挥发性有机化合物（VOCs）的相互作用在自然界中很常见。土壤细菌是各种挥发性化合物（有机和无机）的众所周知的生产者，具有各种与生物相关的活性。自上十年以来，它们已被确定为天然生物防治剂。挥发物是空气传播的化学物质，当细菌释放时，会引发植物的防御和生长促进等反应。在这项研究中，我们测试了土壤细菌分离物产生的可扩散和挥发性有机化合物（VOCs）是否具有抗卵菌和促进植物生长的作用。我们还研究了接种产生 VOC 的细菌对辣椒和拟南芥幼苗生长和发育的影响。我们的结果表明，细菌拮抗剂释放的有机 VOC 在体外对土壤传播的植物病原卵菌辣椒疫霉的菌丝生长有 35%的负面影响。细菌通过刺激生物量生产、主根生长和根毛发育表现出植物生长促进作用。此外，我们提供的证据表明，这些活性是通过可扩散有机化合物或 VOC 的排放来部署的。通过固相微萃取（SPME）和气相色谱-质谱联用（GC-MS）分析获得细菌 VOC 图谱。这阐明了分离物释放的主要挥发物，涵盖了广泛的醛、醇、酯、羧酸和酮。共有 25 种 VOC 被鉴定为由三种细菌产生，其中一些是种特异性的。我们的数据表明，细菌挥发物在体外抑制 P. capsici，并调节植物生长促进和根系发育。这些结果证实了土壤细菌的重要性，并强调了利用它们通过挥发性排放来改善植物生长和作为土壤传播卵菌的生物防治剂的方法值得进一步研究。
