Probiotic Pseudomonas communities enhance plant growth and nutrient assimilation via diversity-mediated ecosystem functioning

Abstract

Plant-associated microbes play an important role in plant growth and development. While the introduction of beneficial microbes into the soil could improve plant production in low-input agricultural systems, real-world applications are still held back by poor survival and activity of the probiotic microbes. In this study, we used a biodiversity-ecosystem functioning (BEF) framework to specifically test how Pseudomonas community richness shapes the bacterial inoculant survival and functioning in terms of plant growth. To this end, we manipulated the richness of a probiotic Pseudomonas spp. bacterial community inoculant (1, 2, 4 or 8 strains per community) and compared diversity and strain identity effects on plant biomass production and nutrient assimilation in vivo with tomato. We found that increasing the richness of the bacterial inoculant enhanced the survival and abundance of Pseudomonas communities leading to higher accumulation of plant biomass and more efficient assimilation of nutrients into the plant tissue. Diversity effects were clearly stronger than the Pseudomonas strain identity effects and diversity-mediated plant growth promotion could be linked with increased production of plant hormones, siderophores and solubilization of phosphorus in vitro. Together these results suggest that multi-strain microbial inoculants can promote plant growth more reliably and effectively compared to single-strain inoculants.

Rhizosphere pseudomonads as probiotics improving plant health

“…Hu et al . () introduced the role of pseudomonads as plant probiotics through their biological control activity.…”

Developing climate‐smart restoration: Can plant microbiomes be hardened against heat waves?

“…Rhizosphere organisms can also benefit plants indirectly, by altering internal (endogenous) production of auxins (Verbon and Liberman ), provisioning nitrogen and phosphorus (Hu et al. ), and through microbe‐to‐microbe facilitation (Dupponois and Garbaye ). In addition, some taxa can physically improve soil structure; arbuscular mycorrhizal hyphal networks enhance soil aggregate stability and improve infiltration (Kohler et al.…”

“…Rhizosphere organisms can directly influence plant growth under stressful conditions by synthesizing phytohormones (Aroca et al 2008, Lim and Kim 2009, Kang et al 2014, amino acids (Ruiz-Lozano et al 1995), and enzymes (Lim and Kim 2013), and by transferring soil water to plant roots (Khalvati et al 2005). Rhizosphere organisms can also benefit plants indirectly, by altering internal (endogenous) production of auxins (Verbon and Liberman 2016), provisioning nitrogen and phosphorus (Hu et al 2017), and through microbe-to-microbe facilitation (Dupponois and Garbaye 1991). In addition, some taxa can physically improve soil structure; arbuscular mycorrhizal hyphal networks enhance soil aggregate stability and improve infiltration (Kohler et al 2017), and some bacteria produce biofilms, a sticky polysaccharide matrix that retains water (Seneviratne et al 2010).…”

“…While plant growth promoting rhizobacteria (PGPR) and AMF have had promising results in glasshouse and field trials, there are potentially negative consequences of the commercialization and global transport of inocula, including loss of native soil biodiversity and even the facilitation of invasive species (Schwartz et al 2006). A diverse soil microbiome has been associated with elevated plant productivity (van der Heijden et al 1998, Hu et al 2017) and resistance to abiotic perturbations (Yachi andLoreau 1998, Awasthi et al 2014). In contrast, the majority of agricultural inoculation studies use only one to three microbial species and typically occur in highly controlled glasshouse conditions, which differs from actual agricultural and restoration scenarios in which hundreds to thousands of microbial taxa might be present.…”

Seed mucilage interacts with soil microbial community and physiochemical processes to affect seedling emergence on desert sand dunes

“…Fungi and bacteria are two main components involved in soil biogeochemical cycles and in performing critical ecological functions by playing distinct roles in plant growth (Strickland & Rousk, ). Previous studies focused mainly on the effects of specific fungi or bacteria on seedling emergence and plant growth (Hu et al, ; Kishore, Pande, & Podile, ), whereas the potential role of interactions between fungi and bacteria on seedling emergence has been ignored. In fact, microbial interactions are also a vitally important character of the microbial community and play key roles in the maintenance of soil microbial community structure (de Menezes, Richardson, & Thrall, ).…”