Exploring how the mountain pine beetle fungal associate ophiostoma clavigerum overcomes lodgepole pine defenses

随着全球贸易和气候变化的增加，加拿大森林的生态和经济可持续性日益受到本地和外来入侵昆虫的威胁，这些昆虫将真菌病原体带到商业和观赏树木上。目前在加拿大西部的山地松甲虫（MPB）流行病说明了这种流行病的破坏性的直接和长期影响的规模，其中涉及宿主，病媒和病原体之间的特定相互作用。MPB的流行是通过甲虫群体的大规模攻击松树和克服树木的防御，然后在树皮下的走廊里繁殖来传播的。携带MPB的真菌是流行病中的关键共生组分，因为它们为甲虫克服树木防御提供了必要的帮助，并随后作为甲虫后代的营养源。当带菌真菌绕过树木的物理和化学防御时，它们迅速在树木的韧皮部和边材中定植，并通过阻止水分运输到树冠来杀死树木。此外，真菌会污染树木的边材，降低木材和木材纤维的工业价值。带菌的真菌是树木病原体;在没有甲虫的情况下接种它们可以杀死树木。我们的主要目标将是蓝变真菌Ophiostoma clavigerum，这是加拿大西部流行病中致病性最强的真菌MPB。 我们的长期目标是阐明真菌致病性的机制。 具体而言，我们将确定天然存在的油性树脂和酚类杀菌剂，是黑松防御系统的主要组成部分，并将表征它们如何干扰O.棒菌我们将使用生物化学和分子方法，利用我们以前的工作中产生的分子试剂。

Given increasing global trade and climate change, the ecological and economical sustainability of Canada's forests are increasingly threatened by native and alien invasive insects that carry fungal pathogens to commercial and ornamental trees. The current mountain pine beetle (MPB) epidemic in western Canada illustrates the scale of the devastating immediate and long-term effects of such epidemics, which involve specific interactions between a host, vector and pathogen. The MPB epidemic spreads by a beetle population mass-attacking lodgepole pine trees and overcoming tree defences, then reproducing in galleries under the bark. The MPB-vectored fungi are a key symbiotic component in the epidemic, because they provide essential help to the beetles in overcoming tree defences and subsequently serve as a nutrient source for the beetle progeny. When the vectored fungi have bypassed a tree's physical and chemical defenses, they rapidly colonize the tree phloem and sapwood, and kill the tree by blocking water transport to the crown. As well, the fungi stain the tree sapwood, reducing the industrial value of the wood and wood fibres. The vectored fungi are tree pathogens; they can kill trees when inoculated without the beetles. Our primary target will be the blue-stain fungus Ophiostoma clavigerum, the most pathogenic fungal MPB associate in the western Canada epidemic. Our long-term objective is to clarify the mechanisms of fungal pathogenicity. Specifically, we will identify naturally occurring oleoresin and phenolic fungicides that are the major components of lodgepole pine defence systems, and will characterize how they interfere with germination and growth of O. clavigerum. We will use biochemical and molecular approaches, taking advantage of molecular reagents generated in our previous work.