Live long and prosper – how to survive extended dormancy

Some animals have evolved to withstand the assault of extreme environmental conditions over long periods when a suitable food source is not available. Plant parasitic nematodes, more specifically the cyst nematodes, are good examples of this. These microscopic animals live in the soil and are dependent on specific species of host plants as food sources. They exhibit remarkable persistence and can survive dormant in the soil for decades before emerging to infect crops. This underlies their status as agriculturally important global pathogens. Currently the control of these obligate parasites represents the largest variable cost to growers of crops such as potatoes. The molecular and biochemical mechanisms that allow this extraordinarily longevity remain unanswered. We have recently identified populations of potato cyst nematode that vary in their persistence i.e. their viability declines at different rates. We have also found that the rate at which nematode viability declines in the soil can be much slower than previously described. This offers a unique opportunity to understand the basic processes that protect the animal across a wide range of extreme environmental conditions.
Cumulative damage to biological macromolecules including DNA, RNA, proteins and lipids occurs in cells during prolonged periods of dormancy. There is thus strong selection pressure to ensure that extending lifespan in dormancy does not compromise subsequent vigour. We hypothesise that, similar to desiccation-tolerant seeds, cyst nematodes have evolved powerful protection and repair mechanisms. Recent advances by co-supervisor Dr West have revealed crucial roles for genome maintenance pathways in the extended survival of seeds in the quiescent state. These features are shared widely amongst anhydrobiotic organisms and provide an exciting new target for understanding and attenuating the nematode lifecycle.

Objectives
• Assess cumulative damage to DNA, proteins and lipid during nematode dormancy.
• Determine the activity of genome maintenance pathways in cyst nematodes after release from dormancy.
• Correlate nematode diapause status with differential protection against cumulative stress.

This project will combine a range of state of the art techniques to reveal how nematodes have adapted to survive for extended periods in the soil. Accumulating cellular damage will be quantified using laser scanning confocal microscopy, cytogenetics and immunological approaches. Nematode cellular responses and adaptive mechanisms will be characterised using qPCR, RNASeq and chromatography. This will provide the first evidence for the molecular basis of nematode longevity in the soil, fundamental to the development of a new suite of control measures.