Saremba Brett M, Tymm Fiona J M, Baethke Kathy, Rheault Mark R, Sherif Sherif M, Saxena Praveen K, Murch Susan J
a Biology, University of British Columbia , Kelowna , British Columbia , Canada.
b Chemistry, University of British Columbia , Kelowna , British Columbia , Canada.
Plant Signal Behav. 2017 May 4;12(5):e1296997. doi: 10.1080/15592324.2017.1296997. Epub 2017 Apr 27.
American Elms were devastated by an outbreak of Dutch Elm Disease is caused by the fungus Ophiostoma novo-ulmi Brasier that originated in Asia and arrived in the early 1900s. In spite of decades of study, the specific mechanisms and disease resistance in some trees is not well understood. the fungus is spread by several species of bark beetles in the genus Scolytus, during their dispersal and feeding. Our objective was to understand elm responses to beetle feeding in the absence of the fungus to identify potential resistance mechanisms. A colony of Scolytus multistriatus was established from wild-caught beetles and beetles were co-incubated with susceptible or resistant American elm varieties in a controlled environment chamber. Beetles burrowed into the auxillary meristems of the young elm shoots. The trees responded to the beetle damage by a series of spikes in the concentration of plant growth regulating compounds, melatonin, serotonin, and jasmonic acid. Spikes in melatonin and serotonin represented a 7,000-fold increase over resting levels. Spikes in jasmonic acid were about 10-fold higher than resting levels with one very large spike observed. Differences were noted between susceptible and resistant elms that provide new understanding of plant defenses.
美国榆树因荷兰榆树病的爆发而遭到重创，该病由源自亚洲并于20世纪初传入的新榆枯萎病菌（Ophiostoma novo-ulmi Brasier）引起。尽管经过了数十年的研究，但某些树木的具体发病机制和抗病性仍未得到充分了解。这种真菌在其扩散和取食过程中，通过几种小蠹属的树皮甲虫传播。我们的目标是了解在没有真菌的情况下榆树对甲虫取食的反应，以确定潜在的抗性机制。从野外捕获的甲虫建立了一个多纹小蠹种群，并将甲虫与易感或抗性美国榆树品种在可控环境舱中共同培养。甲虫钻入幼榆嫩枝的腋生分生组织。树木通过一系列植物生长调节化合物、褪黑素、血清素和茉莉酸浓度的峰值来应对甲虫的侵害。褪黑素和血清素的峰值比静息水平高出7000倍。茉莉酸的峰值比静息水平高出约10倍，观察到一个非常大的峰值。在易感和抗性榆树之间发现了差异，这为植物防御提供了新的认识。
