Plant-Microbe Interactions and Climate Change: How Soil Microorganisms Enhance Plant Resilience and their Precarious Future

Abstract

Plant health is deeply entwined with microbial mutualists, including bacteria, fungi and protists. The rhizosphere is the soil in immediate proximity to root tissue, under the action of plant secretions and signals. Mutualistic associations are important factors in plant adaptability by increasing nutrient and water availability, enhancing plant innate immunity, conveying information between plant hosts, inducing transcriptional and epigenetic changes to increase tolerance, and providing important metabolic services. Anthropogenic climate change is having direct impacts on plant-associated microorganisms. In many soils, warming reduces the functional diversity of soil microbiomes, and favours plant pathogens, whilst reducing immune-supporting microorganisms, although effects vary, reflecting the heterogenous soil environment. Mycorrhizal fungi typically supplement water uptake, but drought decreases fungal growth, increasing plant water stress. There is insufficient data regarding the interactions of multiple climatic factors, which will inevitably coincide under current warming trajectories. This issue is of importance due to the rising demand for food in a world where plant growth is increasingly unfavourable. Advancements in using mutualistic microbial inoculants to bolster yields in developing nations, where there is greatest calorie demand but where climate change is having the greatest negative impacts, could significantly improve human health outcomes. This article will present Sub Saharan Africa as a case study for the role of soil microbiome degradation in exacerbating global inequalities. Soil health in Sub Saharan Africa is threatened by drought, erratic rains and rising temperatures, but the effects on smallholder farmers can be mitigated by conservation agriculture, utilising organic matter applications, microbial inoculants and minimal tilling practices. Importantly, in pursuit of climate justice, capital must be mobilised to developing nations in order to support conservation agriculture projects.