一个国际科研小组9日发布报告说,他们完成了对马铃薯晚疫病病菌的基因测序,这有助于找到对付这一病菌的新手段。晚疫病病菌曾导致历史上著名的爱尔兰大饥荒。
这项研究由美英等多国研究人员联合完成。马铃薯晚疫病病菌基因测序结果显示,与同类生物相比,该病菌有大得出奇的基因图谱,其中74%都是由重复出现的“转位子”组成。
研究人员说,这是一个“疯狂”的比例,通常微生物基因图谱中有25%的“转位子”就已经很多了。“转位子”是具有特定功能的基因片段,它可以自我复制并在基因序列中四处移动,晚疫病病菌正是靠这些“转位子”的作用侵害马铃薯。研究人员认为,晚疫病病菌基因如此演化是为了保持一个庞大的“武器库”,便于迅速适应环境变化。
一名马铃薯育种专家在评论上述成果时说,有时“好不容易费15年时间培育出一种有抵抗力的新品种,晚疫病病菌却只用几年就把它打败”,现在掌握了该病菌的基因图谱和“武器库”特点,将有助于研发能有效对付它的基因手段。
晚疫病病菌会损害马铃薯的叶子和根茎,它在19世纪导致爱尔兰大面积马铃薯绝收,约有100万人因此死亡,还有数百万人因这一病虫害移居海外。据估算,这一病菌目前仍给全球农业造成每年约67亿美元的损失。(生物谷Bioon.com)
生物谷推荐原始出处:
Nature 9 September 2009 | doi:10.1038/nature08358
Genome sequence and analysis of the Irish potato famine pathogen Phytophthora infestans
Brian J. Haas1,35, Sophien Kamoun2,3,35, Michael C. Zody1,4, Rays H. Y. Jiang1,5, Robert E. Handsaker1, Liliana M. Cano2, Manfred Grabherr1, Chinnappa D. Kodira1,36, Sylvain Raffaele2, Trudy Torto-Alalibo3,36, Tolga O. Bozkurt2, Audrey M. V. Ah-Fong6, Lucia Alvarado1, Vicky L. Anderson7, Miles R. Armstrong8, Anna Avrova8, Laura Baxter9, Jim Beynon9, Petra C. Boevink8, Stephanie R. Bollmann10, Jorunn I. B. Bos3, Vincent Bulone11, Guohong Cai12, Cahid Cakir3, James C. Carrington13, Megan Chawner14, Lucio Conti15, Stefano Costanzo16, Richard Ewan15, Noah Fahlgren13, Michael A. Fischbach17, Johanna Fugelstad11, Eleanor M. Gilroy8, Sante Gnerre1, Pamela J. Green18, Laura J. Grenville-Briggs7, John Griffith14, Niklaus J. Grünwald10, Karolyn Horn14, Neil R. Horner7, Chia-Hui Hu19, Edgar Huitema3, Dong-Hoon Jeong18, Alexandra M. E. Jones2, Jonathan D. G. Jones2, Richard W. Jones20, Elinor K. Karlsson1, Sridhara G. Kunjeti21, Kurt Lamour22, Zhenyu Liu3, LiJun Ma1, Daniel MacLean2, Marcus C. Chibucos23, Hayes McDonald24, Jessica McWalters14, Harold J. G. Meijer5, William Morgan25, Paul F. Morris26, Carol A. Munro27, Keith O'Neill1,36, Manuel Ospina-Giraldo14, Andrés Pinzón28, Leighton Pritchard8, Bernard Ramsahoye29, Qinghu Ren30, Silvia Restrepo28, Sourav Roy6, Ari Sadanandom15, Alon Savidor31, Sebastian Schornack2, David C. Schwartz32, Ulrike D. Schumann7, Ben Schwessinger2, Lauren Seyer14, Ted Sharpe1, Cristina Silvar2, Jing Song3, David J. Studholme2, Sean Sykes1, Marco Thines2,33, Peter J. I. van de Vondervoort5, Vipaporn Phuntumart26, Stephan Wawra7, Rob Weide5, Joe Win2, Carolyn Young3, Shiguo Zhou32, William Fry12, Blake C. Meyers18, Pieter van West7, Jean Ristaino19, Francine Govers5, Paul R. J. Birch34, Stephen C. Whisson8, Howard S. Judelson6 & Chad Nusbaum1
Phytophthora infestans is the most destructive pathogen of potato and a model organism for the oomycetes, a distinct lineage of fungus-like eukaryotes that are related to organisms such as brown algae and diatoms. As the agent of the Irish potato famine in the mid-nineteenth century, P. infestans has had a tremendous effect on human history, resulting in famine and population displacement1. To this day, it affects world agriculture by causing the most destructive disease of potato, the fourth largest food crop and a critical alternative to the major cereal crops for feeding the world's population1. Current annual worldwide potato crop losses due to late blight are conservatively estimated at $6.7 billion2. Management of this devastating pathogen is challenged by its remarkable speed of adaptation to control strategies such as genetically resistant cultivars3, 4. Here we report the sequence of the P. infestans genome, which at 240 megabases (Mb) is by far the largest and most complex genome sequenced so far in the chromalveolates. Its expansion results from a proliferation of repetitive DNA accounting for 74% of the genome. Comparison with two other Phytophthora genomes showed rapid turnover and extensive expansion of specific families of secreted disease effector proteins, including many genes that are induced during infection or are predicted to have activities that alter host physiology. These fast-evolving effector genes are localized to highly dynamic and expanded regions of the P. infestans genome. This probably plays a crucial part in the rapid adaptability of the pathogen to host plants and underpins its evolutionary potential.