Microbiomes and Land-use Intensification

Agricultural intensification is one of the major problems of the 21st century that alters the local biodiversity and affects ecosystem processes. The total area of cultivated land worldwide has increased over 500% in the last five decades with a 700% increase in the fertilizer use and a several-fold increase in pesticide use. Soil and plant- associated microbes play a key role in determining the above-ground productivity. Therefore, understanding the effect of agricultural intensification on microbial communities is essential for the productivity and sustainability of ecosystems. In a previous study, we reported that intensive land-use reduces root microbiome complexity and the abundance of keystone taxa, while sustainable practices promote beneficial microbes that enhance nutrient availability (Banerjee et al., 2019 ISME Journal). Our lab explores the impact of land-use intensification on soil and plant microbes at different spatial scales.

Plant-Microbe Interactions

Invasions of non-native species cause significant ecological and economic impacts worldwide, affecting both managed and native ecosystems. The threat posed by invasive plant species is considered to be the second most significant factor contributing to the endangerment of native species after habitat fragmentation. While much research has been conducted on the direct and indirect plant-soil feedbacks with local vegetation, studies investigating the effects of invasive plant species on the soil microbiome are limited. We explore how invasive plants can alter the soil microbial communities and how microbes can determine the invasion outcome.

Microbe-Microbe Interactions and Keystone Taxa 

Microbial keystone taxa are highly connected taxa that individually or in a guild exert a strong influence on microbiome structure and functioning irrespective of their abundance across space and time. In recent years, studies observing the human gut microbiome has provided empirical data that has determined keystone taxa to play a role in such processes as microbiota stabilization, inflammation, gastric cancer, etc. While much of the empirical data on keystone taxa originates from the human microbiome, studies targeting the marine, plant and soil microbiomes are also gaining traction. Once keystone taxa are identified, microbiome functions may be manipulated for a desired outcome. The keystone taxa project will build on previous findings and explore the ecological rules that govern microbial associations and if keystone taxa pull more weight in the community.

Microbiomes and Global Change Factors

Soil salinity is a common agricultural problem that occurs globally. Soil salinity is estimated to affect approximately 800 million hectares globally and in 30 years is predicted to affect half of all arable land. In North Dakota, approximately 280,000 hectares across 34 of the 52 counties are characterized as saline soils. The excessive accumulation of soluble salts is detrimental to crop production by causing drought stress or tissue damage. The presence of soluble salts within a soil solution changes the osmotic potential, which consequently alters the interaction between the soil solution and root diffusion barriers. Drought stress is then induced when the amount of energy needed to uptake the water from the soil solution increases for the plant across the entire root membrane. Saline soils can also cause physiological damage such as stunting, chlorosis, and plant cell necrosis through the accumulation of salt constituents within the plant root tissue. However, mycorrhizal fungi can alleviate the effects of soil salinity. Mycorrhizal fungi are symbiotic fungi that improve plant nutrient uptake, water absorption, plant growth and protection from soil-borne pathogens. Our research addresses mycorrhizal colonization in saline soils of North Dakota and identifying salt tolerant strains. 

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