Whitehill Justin G A, Henderson Hannah, Strong Ward, Jaquish Barry, Bohlmann Jörg
Michael Smith Laboratories, University of British Columbia, 301-2185 East Mall, Vancouver, British Columbia, Canada, V6T 1Z4.
British Columbia Ministry of Forests, Lands and Natural Resource Operations, Tree Improvement Branch, Kalamalka Forestry Centre, 3401 Reservoir Road, Vernon, British Columbia, Canada, V1B 2C7.
Plant Cell Environ. 2016 Nov;39(11):2545-2556. doi: 10.1111/pce.12810. Epub 2016 Sep 19.
Stone cells are a physical defence of conifers against stem feeding insects such as weevils and bark beetles. In Sitka spruce, abundance of stone cells in the cortex of apical shoot tips is associated with resistance to white pine weevil. However, the mode of action by which stone cells interfere with growth and development of weevil larvae is unknown. We developed a bioassay system for testing potential effects of stone cells, which were isolated from resistant trees, on weevil larvae. Bioassays using artificial diet and controlled amounts of stone cells focused on physical defence. We evaluated the effects of stone cells on establishment of neonate larvae, mandible wear and changes in relative growth rates of third instar larvae. Establishment of neonates and relative growth rates of third instars were significantly reduced by stone cells. Stone cells appeared to be indigestible by weevil larvae. Our results suggest that stone cells affect weevil establishment and development by forming a physical feeding barrier against neonate larvae at the site of oviposition, and by reducing access to nutrients in the cortex of resistant trees, which contain an abundance of stone cells in place of a more nutrient rich tissue in susceptible trees.
石细胞是针叶树抵御象鼻虫和树皮甲虫等蛀干昆虫的一种物理防御机制。在西加云杉中，顶端梢尖皮层中石细胞的数量与对白松象鼻虫的抗性有关。然而，石细胞干扰象鼻虫幼虫生长发育的作用方式尚不清楚。我们开发了一种生物测定系统，用于测试从抗性树木中分离出的石细胞对象鼻虫幼虫的潜在影响。使用人工饲料和控制量的石细胞进行的生物测定主要关注物理防御。我们评估了石细胞对初孵幼虫定殖、下颚磨损以及三龄幼虫相对生长率变化的影响。石细胞显著降低了初孵幼虫的定殖率和三龄幼虫的相对生长率。石细胞似乎无法被象鼻虫幼虫消化。我们的研究结果表明，石细胞通过在产卵部位形成一道针对初孵幼虫的物理取食屏障，并减少抗性树木皮层中营养物质的获取，从而影响象鼻虫的定殖和发育。在抗性树木中，富含石细胞的皮层取代了易感树木中营养更丰富的组织。
