Microbial-Mediated Plant Growth Promotion and Pest Suppression Varies Under Climate Change.

Sharon E Zytynska,Wolfgang W Weisser,Michael Rothballer,Moritz Eicher

doi:10.3389/fpls.2020.573578

Sharon E Zytynska, Wolfgang W Weisser + Show 2 more

Open Access

https://doi.org/10.3389/fpls.2020.573578

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Abstract

Climate change is altering the dynamics of crop pests and diseases resulting in reduced crop yields. Using beneficial soil bacterial to increase crop health is a quickly developing area in sustainable agriculture, but it is unknown if climate change or interactions with other species could alter their effect. The plant growth-promoting rhizobacterium Acidovorax radicis N35 is known to increase barley (Hordeum vulgare) plant growth under laboratory conditions, and we tested the stability of the plant-bacterial interactions when exposed to elevated carbon dioxide (CO2) and ozone (O3) levels while infesting the aboveground leaves with cereal aphids (Sitobion avenae) and the soil with beneficial earthworms. Acidovorax radicis N35 increased plant growth and reduced insect growth – with greatest effect in a high-stress elevated O3 environment, but reduced effects under elevated CO2. Earthworms promoted both plant and insect growth, but inoculation with A. radicis N35 alleviated some of the earthworm-mediated increase in pest abundance, particularly in the ambient environment. The consistency of these beneficial effects highlights the potential of exploiting local species interactions for predicting and mitigating climate change effects in managed systems. We conclude that microbial bioprotectants have high potential for benefiting agriculture via plant-growth promotion and pest suppression.

Highlights

Climate change is predicted to expand insect pest range distributions and shift insect phenology (Tylianakis et al, 2008), resulting in increased chances of pest outbreaks
Our study species included: (1) four European barley (Hordeum vulgare) plant cultivars: Barke (Saatzucht Breun GmbH), Chevallier (New Heritage Barley Ltd), Grace (Ackermann Saatzucht GmbH), and Scarlett (Saatzucht Breun GmbH); (2) the English grain aphid Sitobion avenae (L.) that had been maintained as low density stock populations on Barley cultivar “Kym” in a climate cabinet for two years, the clone was originally from Goettingen University; (3) epigeic earthworms Dendrobaena veneta Rosa 1886, originally from wurmwelten.de and maintained in a Worm-Café® for three years prior to the experiment; and (4) the rhizobacteria Acidovorax radicis N35 prepared by colleagues from the Helmholtz Zentrum Munich, along with a control solution containing no bacteria for seedling inoculation
While our analyses uncovered multiple interactions between the climate and biotic factors on plant growth and aphid density (Figures 1B, C; Table S1), meaning that the effect of one factor depended on others, most of the results could be simplified to a set of factors that together are important for the outcome (Figure 1D)

Summary

Introduction

Climate change is predicted to expand insect pest range distributions and shift insect phenology (Tylianakis et al, 2008), resulting in increased chances of pest outbreaks. Understanding the complexities of these interactions is necessary in order to predict future outcomes and develop solutions to mitigate these effects. This means going beyond studying pairwise, or even tri-trophic systems, and performing larger multi-factorial experiments that enable us to disentangle the complex interactions and identify emergent properties novel to these multi-species communities (Levine et al, 2017). Management of cropping systems disrupts these natural processes (Seibold et al, 2019), but one solution is to identify and promote beneficial interactions that can buffer the effects of climate change on crop plants. The use of bioprotectants is very promising, and we expand upon this to ask if these beneficial effects are maintained across different biotic and climate environments

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