Moravčík Michal, Mamoňová Miroslava, Račko Vladimír, Kováč Ján, Dvořák Miloň, Krajňáková Jana, Ďurkovič Jaroslav
Department of Phytology, Technical University in Zvolen, T.G. Masaryka 24, 96001 Zvolen, Slovakia.
Department of Pesticide Registration, ÚKSÚP Bratislava, SNP 99, 96202 Vígľaš, Slovakia.
J Fungi (Basel). 2022 Feb 22;8(3):215. doi: 10.3390/jof8030215.
The ascomycetous fungus is the causative agent of the current Dutch elm disease (DED) pandemic, which has ravaged many tens of millions of European and North American elm trees. Host responses in vascular traits were studied in two Dutch elm hybrids, 'Groeneveld' and 'Dodoens', which show different vascular architecture in the secondary xylem and possess contrasting tolerances to DED. 'Groeneveld' trees, sensitive to DED, possessed a high number of small earlywood vessels. However, these trees showed a poor response to DED infection for the earlywood vascular characteristics. Following infection, the proportion of least vessels with a vessel lumen area less than 2500 µm decreased from 65.4% down to 53.2%. A delayed response in the increasing density of vessels showing a reduced size in the latewood prevented neither the rapid fungal spread nor the massive colonisation of the secondary xylem tissues resulting in the death of the infected trees. 'Dodoens' trees, tolerant to DED, possessed a low number of large earlywood vessels and showed a prominent and fast response to DED infection. Vessel lumen areas of newly formed earlywood vessels were severely reduced together with the vessel size : number ratio. Following infection, the proportion of least vessels with a vessel lumen area less than 2500 µm increased from 75.6% up to 92.9%. A trend in the increasing density of vessels showing a reduced size was maintained not only in the latewood that was formed in the year of infection but also in the earlywood that was formed in the consecutive year. The occurrence of fungal hyphae in the earlywood vessels that were formed a year following the infection was severely restricted, as revealed by X-ray micro-computed tomography imaging. Possible reasons responsible for a contrasting survival of 'Groeneveld' and 'Dodoens' trees are discussed.
子囊菌是当前荷兰榆树病（DED）大流行的病原体，这种病害已经摧毁了数千万棵欧洲和北美的榆树。在两个荷兰榆树杂交品种“Groeneveld”和“Dodoens”中研究了维管性状的宿主反应，这两个品种在次生木质部中显示出不同的维管结构，并且对DED具有不同的耐受性。对DED敏感的“Groeneveld”树拥有大量小的早材导管。然而，这些树对DED感染的早材维管特征反应不佳。感染后，管腔面积小于2500 µm²的最小导管比例从65.4%降至53.2%。晚材中导管密度增加且尺寸减小的延迟反应既不能阻止真菌的快速传播，也不能阻止次生木质部组织的大量定殖，从而导致受感染树木死亡。对DED具有耐受性的“Dodoens”树拥有少量大的早材导管，并且对DED感染表现出显著且快速的反应。新形成的早材导管的管腔面积以及导管大小与数量之比都大幅降低。感染后，管腔面积小于2500 µm²的最小导管比例从75.6%增至92.9%。不仅在感染当年形成的晚材中，而且在次年形成的早材中，都保持了导管密度增加且尺寸减小的趋势。X射线微计算机断层扫描成像显示，感染一年后形成的早材导管中真菌菌丝的出现受到严重限制。讨论了“Groeneveld”和“Dodoens”树存活情况不同的可能原因。
