Potatoes are edible tubers, available worldwide and all year long. The crop is relatively cheap to grow and its tubers are rich in nutrients, and they can make a delicious treat. However, productivity of this crop and tuber quality is hugely threatened by microbial pathogens. Both fungal and bacterial soil pathogens are known to cause severe yield loses across the globe. Some of its common diseases include; soft rots, ring rot, common scab and late blight.
To control the diseases, farmers usually use inorganic pesticides while, others grow potato varieties developed to genetically resist some of these pathogens. Inorganic pesticides are expensive; hence they increase cost of production. Furthermore, inorganic pesticides affects non-target organisms, thereby impacting negatively on ecosystem functioning and biodiversity. Hence, control strategies that are ecosystem friendly are required. Use of microbial antagonists is suggested as a sustainable way to control plant diseases. However, antagonists of pathogens that affect potato plants are not yet well documented.
Therefore, I propose to establish trials of both, newly developed and commercial cultivars of potatoes at four locations in Zimbabwe, which are known as hotspots of the major diseases. From these locations, soil samples will be collected from the rhizosphere of plants showing symptoms of the major diseases (i.e., susceptible plants) and also from those plants not showing any symptoms (i.e., resistant plants). In order to identify microbial strains (i.e., both pathogens & symbionts) residing in the rhizosphere soil environment of potatoes, the intra-transcribed spacer (ITS) region as well as the 16S rRNA amplicon sequences will be used for fungal and bacterial diversity analysis, respectively. Bioinformatics pipelines and R tools will be employed to achieve this. Using this strategy, comparisons of soil microbial profiles in the rhizosphere soil environment of susceptible and resistant plants will be done; therefore it will be possible to identify microbial taxa that are populated by resistant plants in their soil environment. I hypothesize that, some of the bacterial and fungal taxa populated by resistant potato cultivars in their rhizosphere environment have the ability to antagonize the pathogenic strains. If the identities of antagonists of pathogens of potato plants are identified, these can be cultured and purified, and can be inoculated on potato tubers during planting as bio-protectants.
Casper Nyaradzai Kamutando, Zimbabwe