Key message

The novel incubation system where antifungal activities of bark tissues against Trametes versicolor were evaluated revealed that the inner bark of Sorbus commixta strongly inhibits mycelial growth of T. versicolor.

Abstract

Tree barks protect inside of tree bodies against pathogen invasion, but their chemical constitutive defense mechanisms remain largely unexplored. Therefore, the antifungal activities of bark tissues of 25 tree species acquired from Hokkaido, Japan, were examined to investigate the constitutive chemical defense mechanisms of tree barks. Bark pieces were placed on potato dextrose agar with Trametes versicolor after sterilization with gamma rays at 15 kGy. Bark tissues of most species exhibited limited activities. However, the whole and inner barks of Sorbus commixta completely inhibited the mycelial growth of T. versicolor. Furthermore, the inner bark of S. commixta on media with grooves also inhibited the mycelial growth of T. versicolor, indicating that antifungal substances generated from the inner bark of S. commixta are volatile. Among other species, Cerasus sargentii var. sargentii, Picea jezoensis var. jesoensis, and Magnolia obovate showed lower antifungal activities than S. commixta. We also examined the validity of 15 kGy for sterilizing the bark pieces of 16 species among 25 species. A dose of 12 kGy was sufficient to sterilize the bark pieces of all species, except Abies sachalinensis, and 15 kGy was necessary for the bark pieces of A. sachalinensis. In conclusion, this incubation system can be applied to select tree species, such as S. commixta, with high antifungal activities, and 15 kGy was sufficient for this incubation system to sterilize the barks of tree species in Hokkaido. This incubation system is useful to find out tree species that form bark tissues with unique chemical defense mechanisms.

中文翻译：

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使用栓菌孵化系统评价木本植物树皮的抗真菌活性

关键信息

评估了树皮组织对云芝菌的抗真菌活性的新型培养系统表明，花梨的内树皮强烈抑制云芝菌丝体的生长。

抽象的

树皮保护树体内部免受病原体入侵，但其化学构成防御机制在很大程度上仍未被探索。因此，对从日本北海道获得的 25 种树种的树皮组织的抗真菌活性进行了检测，以研究树皮的化学防御机制。用 15 kGy 的伽马射线灭菌后，将树皮碎片置于含有栓菌的马铃薯葡萄糖琼脂上。大多数物种的树皮组织表现出有限的活性。然而，花梨的整个树皮和内皮完全抑制了云芝菌丝体的生长。此外，在有凹槽的培养基上， S.commixta的内皮也抑制了T. versicolor菌丝的生长，这表明S.commixta内皮产生的抗真菌物质具有挥发性。在其他物种中，Cerasus sargentii var. 沙金云杉_ _ jesoensis和Magnolia obovate 的抗真菌活性低于S. commixta。我们还检验了 15 kGy 对 25 个物种中 16 个物种的树皮碎片进行灭菌的有效性。12 kGy 的剂量足以对除大漠冷杉外的所有物种的树皮片进行灭菌，而对于大漠冷杉的树皮片则需要 15 kGy 的剂量。总之，该孵化系统可以应用于选择具有高抗真菌活性的树种，例如S.comixta，15 kGy 足以对该孵化系统对北海道树种的树皮进行消毒。该孵化系统有助于找出形成具有独特化学防御机制的树皮组织的树种。