EFFECT OF GENE DISRUPTION OF TRICHODIENE SYNTHASE ON THE VIRULENCE OF GIBBERELLA-PULICARIS
EFFECT OF GENE DISRUPTION OF TRICHODIENE SYNTHASE ON THE VIRULENCE OF GIBBERELLA-PULICARIS
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DOI：
10.1094/mpmi-5-214
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发表时间：
1992-05-01
影响因子：
3.5
通讯作者：
MCCORMICK, SP
中科院分区：
文献类型：
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作者：
DESJARDINS, AE;HOHN, TM;MCCORMICK, SP
赤霉病菌（无性型：接骨木镰刀菌（Fusarium sambucinum）积累了一种有效的宿主非特异性植物毒素和真核蛋白质合成抑制剂-为了研究DAS在植物发病机理中的作用，我们测试了5个潮霉素抗性（Hyg（r））转化体的毒力，所述转化体携带破坏的双烯合酶（Tox 5）基因并且不再在体外或在植物中产生DAS。所有5个DAS-转化体的毒力水平在欧洲防风根切片上降低，但在马铃薯块茎切片上保留了高水平的毒力。四分体分析的一个菌株BC 51，其中携带一个单拷贝的转化质粒，导致共分离的Hyg（r）DAS-，防风草降低毒力表型或在所有三个性状的同时损失。与此相反，所有这些四分体的后代，无论DAS+或DAS-，是高度有毒的马铃薯块茎。此外，Hyg（r）DAS-表型在马铃薯块茎中在一个3周循环后以高频率从混合群体中恢复，这表明DAS生产的损失并没有降低病原体的竞争力。DAS的积累增加了G. pulicaris对防风草根的毒性，但不影响对马铃薯块茎的毒性。DAS在毒力中的重要性的主机上的明显效果仍然是无法解释的，但它表明，在评估的作用，在植物病害中的dathecenes，一个应该谨慎的概括结果从一个植物物种到另一个。
Gibberella pulicaris (anamorph: Fusarium sambucinum) accumulates the trichothecene, 4,15-diacetoxyscirpenol (DAS), a potent, host-nonspecific phytotoxin and eukaryotic protein synthesis inhibitor. To investigate the role of DAS in plant pathogenesis, we tested the virulence of five hygromycin-resistant (Hyg(r)) transformants that carry a disrupted gene for trichodiene synthase (Tox5) and no longer produce DAS in vitro or in planta. Virulence levels of all five DAS- transformants were reduced on parsnip root slices, but high levels of virulence were retained on potato tuber slices. Tetrad analysis of one transformant, strain BC51, which carried a single copy of the transforming plasmid, resulted in either cosegregation of the Hyg(r) DAS-, parsnip reduced-virulence phenotypes or in the simultaneous loss of all three traits. In contrast, all progeny from these tetrads, whether DAS+ or DAS-, were highly virulent on potato tubers. Moreover, the Hyg(r) DAS- phenotype was recovered at high frequency from mixed populations after one 3-wk cycle in potato tubers, which suggested that loss of DAS production did not reduce competitiveness of the pathogen. We conclude that DAS accumulation increases the virulence of G. pulicaris on parsnip root but does not affect virulence on potato tubers. The apparent effect of the host on the importance of DAS in virulence is still unexplained, but it suggests that when assessing the role of trichothecenes in plant disease, one should be cautious in generalizing results from one plant species to another.