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New strategies for protecting pine trees from pine wilt disease

保护松树免受松枯萎病的新策略

基本信息

批准号：
09556037
负责人：
KURODA Hiroyuki
金额：
$ 8.96万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

Embolism in a microtomed pine (Pinus densiflora) section was recorded by a video-monitor under a microscope during counting the acoustic emission from the section. The event numbers were increased when embolism occurred. This observation led a conclusion that the embolism was not recovered in nematode inoculated pine trees while it does in the sound tree. Thus, this irreversible embolism splits water conducts and it results in the tree death.Systemic chemicals were screened by nematode inoculation test in pine (Pinus densiflora ) seedlings. We found that a new chemical was induced resistance against the nematode induced wilting in the seedlings. In 3-year-old nursery stocks, a commercial systemic chemical was effective against the wilting, the symptom of which was reduced, e.g., only dieback of the inoculated branches, delay of wilting. The chemical had induced nematicidal stilbenoids in the base of branches but not in young shoots. Thus, the base of branches plays important role for stopping the nematode movement. Another point is variation of the stilbenoid levels in the pine population. The variation suggest that nematode resistant lines may be selected by stilbenoid level.Because we found that stilbenoid formation is one of the key strategies for preventing pine wilt diseases, stilbene synthase genes, a step of which is a rate limiting for stilbenoid formation, were cloned from Pinus densiflora and characterized. Three new genes with full coding sequence was successfully expressed in E.coli. One of them was confirmed stilbene synthase activity. Thus the clones obtained will be available to construct a transgenic pine tree that carries resistance against pine wilt diseases.

在显微镜下的视频监视器记录栓塞在显微切片的松树（赤松）部分从部分的声发射计数期间。发生栓塞时，事件数量增加。这一观察结果得出的结论是，在线虫接种的松树中，栓塞没有恢复，而在健全的树中。通过线虫接种试验，筛选出对赤松（Pinus densiflora）幼苗有较强内吸作用的化学物质。我们发现一种新的化学物质对线虫引起的幼苗萎蔫具有诱导抗性。在3年生苗木中，商业内吸化学品对萎蔫有效，其症状减轻，例如，接种后枝条仅枯死，萎蔫延迟。该化学品在枝条基部诱导杀线虫的芪类化合物，但在嫩枝中不诱导。因此，枝条基部对阻止线虫运动起着重要作用。另一点是松树种群中芪类化合物水平的变化。由于我们发现二苯乙烯类化合物的形成是防治松材线虫病的关键策略之一，因此我们从赤松中克隆了二苯乙烯合成酶基因，并对其进行了鉴定。在大肠杆菌中成功表达了3个新基因。其中之一是证实芪合酶活性。因此，获得的克隆将可用于构建抗松树枯萎病的转基因松树。