Monds Russell D, Cromey Matthew G, Lauren Denis R, di Menna Margaret, Marshall John
New Zealand Institute for Crop & Food Research Limited, Private Bag 4704, Christchurch, New Zealand.
Mycol Res. 2005 Apr;109(Pt 4):410-20. doi: 10.1017/s0953756204002217.
Fusarium graminearum and F. pseudograminearum are important plant pathogens in New Zealand and around the world. Headblight and crown rot diseases of cereals caused by these species are responsible for large economic losses due to reduction in seed quality and contamination of grain with tricothecene mycotoxins. In the current study we have used two different molecular phylogenetic approaches, AFLPs and gene genealogies, to gain insight into the evolutionary relationships between F. graminearum, and F. pseudograminearum in New Zealand. The worldwide genetic diversity of F. graminearum clade is represented by at least eight biogeographically distinct species (previously designated as lineages of F. graminearum). Our analysis demonstrated that this clade is represented by F. graminearum (= F. graminearum Lineage 7) and F. cortaderiae (= F. graminearum Lineage 8) in New Zealand. Through our analysis we also confirm the presence of F. pseudograminearum in New Zealand as a first record for this organism. Information on species is necessary for preventing the inadvertent intercontinental introduction of genetically unique foreign pathogens associated with world trade. The ability to place species information into a worldwide context enabled postulation that the New Zealand representatives of F. graminearum clade originated from at least two regions, and probably on at least two hosts. Correlation of species descriptions with biogeographical and host information revealed evidence for co-localisation of F. graminearum clade species with potential for genetic outcrossing in the field. Mycotoxin analysis showed F. graminearum (= lineage 7) isolates produce either nivalenol (NIV) or deoxnivalenol (DON). In contrast, F. cortaderiae isolates produced only NIV. These findings support earlier observations that mycotoxin production in the F. graminearum clade is not species specific, but suggest maintenance of chemotype diversity through speciation may have been restricted to a subset of species.
禾谷镰刀菌和拟禾谷镰刀菌是新西兰乃至全球重要的植物病原菌。这些菌种引起的谷物赤霉病和冠腐病会导致种子质量下降以及谷物被单端孢霉烯族霉菌毒素污染，从而造成巨大经济损失。在当前研究中，我们使用了两种不同的分子系统发育方法，即扩增片段长度多态性（AFLP）和基因谱系，来深入了解新西兰的禾谷镰刀菌和拟禾谷镰刀菌之间的进化关系。禾谷镰刀菌进化枝的全球遗传多样性由至少八个生物地理上不同的物种（以前被指定为禾谷镰刀菌的谱系）代表。我们的分析表明，在新西兰，这个进化枝由禾谷镰刀菌（=禾谷镰刀菌谱系7）和科塔德镰刀菌（=禾谷镰刀菌谱系8）代表。通过我们的分析，我们还确认了新西兰存在拟禾谷镰刀菌，这是该生物体的首次记录。物种信息对于防止与世界贸易相关的具有遗传独特性的外来病原体的无意洲际引入至关重要。将物种信息置于全球背景下的能力使得我们能够推测，禾谷镰刀菌进化枝在新西兰的代表至少起源于两个地区，并且可能至少寄生于两种寄主植物。物种描述与生物地理和寄主信息的相关性揭示了禾谷镰刀菌进化枝物种在田间可能发生基因杂交的共定位证据。霉菌毒素分析表明，禾谷镰刀菌（=谱系7）分离株产生雪腐镰刀菌烯醇（NIV）或脱氧雪腐镰刀菌烯醇（DON）。相比之下，科塔德镰刀菌分离株仅产生NIV。这些发现支持了早期的观察结果，即禾谷镰刀菌进化枝中的霉菌毒素产生并非物种特异性的，但表明通过物种形成维持化学型多样性可能仅限于一部分物种。
