Hosseini Afsane, Hosseini Mojtaba, Schausberger Peter
Department of Plant Protection, College of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.
Department of Behavioral and Cognitive Biology, University of Vienna, Vienna, Austria.
Front Plant Sci. 2022 Jan 6;12:783578. doi: 10.3389/fpls.2021.783578. eCollection 2021.
Plants mediate interactions between below- and above-ground microbial and animal communities. Microbial communities of the rhizosphere commonly include mutualistic symbionts such as mycorrhizal fungi, rhizobia and free-living plant growth-promoting rhizobacteria (PGPR) that may influence plant growth and/or its defense system against aboveground pathogens and herbivores. Here, we scrutinized the effects of three PGPR, , , and , on life history and population dynamics of two-spotted spider mites, , feeding on aboveground tissue of strawberry plants, and examined associated plant growth and physiology parameters. Our experiments suggest that these three species of free-living rhizobacteria strengthen the constitutive, and/or induce the direct, anti-herbivore defense system of strawberry plants. All three bacterial species exerted adverse effects on life history and population dynamics of and positive effects on flowering and physiology of whole strawberry plants. Spider mites, in each life stage and in total, needed longer time to develop on PGPR-treated plants and had lower immature survival rates than those fed on chemically fertilized and untreated plants. Reduced age-specific fecundity, longer developmental time and lower age-specific survival rates of mites feeding on rhizobacteria treated plants reduced their intrinsic rate of increase as compared to mites feeding on chemically fertilized and control plants. The mean abundance was lower in spider mite populations feeding on PGPR-treated strawberries than in those feeding on chemically fertilized and untreated plants. We argue that the three studied PGPR systemically strengthened and/or induced resistance in above-ground plant parts and enhanced the level of biochemical anti-herbivore defense. This was probably achieved by inducing or upregulating the production of secondary plant metabolites, such as phenolics, flavonoids and anthocyanins, which were previously shown to be involved in induced systemic resistance of strawberry plants. Overall, our study emphasizes that PGPR treatment can be a favorable strawberry plant cultivation measure because providing essential nutrients needed for proper plant growth and at the same time decreasing the life history performance and population growth of the notorious herbivorous pest .
植物介导地下和地上微生物及动物群落之间的相互作用。根际微生物群落通常包括互利共生体，如菌根真菌、根瘤菌和自由生活的促植物生长根际细菌（PGPR），它们可能影响植物生长和/或其针对地上病原体和食草动物的防御系统。在此，我们仔细研究了三种PGPR，即[具体菌株1]、[具体菌株2]和[具体菌株3]，对取食草莓植株地上组织的二斑叶螨的生活史和种群动态的影响，并检测了相关的植物生长和生理参数。我们的实验表明，这三种自由生活的根际细菌增强了草莓植株的组成型防御，和/或诱导了其直接的抗食草动物防御系统。所有这三种细菌对二斑叶螨的生活史和种群动态都产生了不利影响，而对整个草莓植株的开花和生理产生了积极影响。在每个生命阶段以及总体上，叶螨在经PGPR处理的植株上发育所需时间更长，与取食化肥处理和未处理植株的叶螨相比，其未成熟存活率更低。与取食化肥处理和对照植株的叶螨相比，取食根际细菌处理植株的叶螨特定年龄繁殖力降低、发育时间延长且特定年龄存活率降低，从而降低了其内在增长率。取食经PGPR处理草莓的叶螨种群平均丰度低于取食化肥处理和未处理草莓的叶螨种群。我们认为，所研究的这三种PGPR系统性地增强和/或诱导了地上植物部分的抗性，并提高了生化抗食草动物防御水平。这可能是通过诱导或上调次生植物代谢产物如酚类、黄酮类和花青素的产生来实现的，此前已表明这些物质参与草莓植株的诱导系统抗性。总体而言，我们的研究强调，PGPR处理可以是一种有利的草莓种植措施，因为它既能提供植物正常生长所需的必需养分，同时又能降低臭名昭著的食草害虫的生活史表现和种群增长。
