Abstract
Forests are our most abundant renewable resource providing raw material for a multitude of industrial applications but also constitute a major habitat for biodiversity and sinks for carbon. Several tree species have recently been threatened by emerging diseases. The most sustainable and environmental friendly way to handle tree disease is to improve the growing material by breeding for resistance or tolerance to disease. This requires an understanding of the mechanisms for recognition and interaction between trees and their pathogens. Our on-going studies have revealed a novel and important role for small RNA (sRNA) in the regulation of resistance genes of the NBS-LRR class (R genes) in Norway spruce. Our hypothesis is that specific miRNA normally repress NBS-LRR genes through triggering of siRNA production at these loci, and that effector proteins delivered by pathogens to attenuate resistance responses also reduce the expression of those miRNAs. This would in turn result in an upregulation of NBS-LRR gene expression, and thus constitute a counter-counter defence mechanism evolved in the host. Our aim is to test this intriguing hypothesis in Norway spruce, as this mechanism seems to be particularly predominant in long-lived perennial species. Specifically, we want to describe the sRNA-mediated mechanisms controlling the expression of NBS-LRR genes in trees, and study its involvement in resistance against different groups of pathogens in Norway spruce.
Sweden