Project description:Frost is a major abiotic stress limiting plant growth and development. Climate change models predict an increase in the magnitude and frequency of late-frost events, which, together with an observed loss of soil insulation, will significantly damage roots. To withstand freezing stress, plants have evolved an adaptative process known as cold acclimation. While this process is well documented, it is known that the plant response to multiple stresses is unique and cannot be deduced from the response to each stress taken separately. Here, we investigate the impact of long-term metal exposure on the cold acclimation of Salix viminalis roots. To do so, we used physiological, transcriptomic and proteomic approaches. We found that while metal exposure significantly affected plants morphology and physiology, it did not impede cold acclimation. The impact of the simultaneous exposure to metals and cold acclimation on the transcriptome was unique, while at the proteomic level, the cold acclimation component seemed to be dominant. Further analysis revealed that metals strongly and negatively impacted the cellular antioxidant system. While this should have led to a loss of frost tolerance, it was not observed. A group of proteins was identified that could have played a role in compensating the impediment of the antioxidative system in metal-exposed roots.
Project description:Shrub willow (Salix spp.), a short rotation woody biomass crop, has superior properties as a perennial energy crop for the Northeast and Midwest US. However, the insect pest potato leafhopper Empoasca fabae (Harris) (PLH) can cause serious damage and reduce yield of susceptible genotypes. Currently, the willow cultivars in use display varying levels of susceptibility under PLH infestation. However, genes and markers for resistance to PLH are not yet available for marker-assisted selection in breeding. In this study, transcriptome differences between a resistant genotype 94006 (S. purpurea) and a susceptible cultivar ‘Jorr’ (S. viminalis), and their hybrid progeny were determined. Over 600 million RNA-Seq reads were generated and mapped to the Salix purpurea reference transcriptome. Gene expression analyses revealed the unique defense mechanism in resistant genotype 94006 that involves PLH-induced secondary cell wall modification. In the susceptible genotypes, genes involved in programed cell death were highly expressed, explaining the necrosis symptoms after potato leafhopper feeding. Overall, the discovery of resistance genes and defense mechanisms provides new resources for shrub willow breeding and research in the future.
