玉米条纹病毒导致了全世界经济损失最严重的作物疾病之一
非洲科学家发现了全世界经济损失最严重的作物疾病之一是如何出现的，他们希望利用这些信息培育抗病的转基因作物。
科学家比较了非洲大陆各地毒力很强的玉米条纹病毒（MSV）和毒力稍弱的这种病毒的遗传序列，该病毒可以感染其他草本粮食作物，例如小麦和燕麦。
来自南非开普敦大学的科学家Arvind Varsani说：“我们发现两种相对温和的草病毒通过遗传重组而合并。”
这种合并导致了比它的祖先毒力更强的古代MSV病毒，在它迅速传遍非洲大陆之前就具有了感染玉米的能力。
这组科学家认为这发生在大约一个世纪之前，就在商业农业取代生存农业、而玉米开始取代非洲本土作物的时候。
这项发现发表在了《普通病毒学杂志》9月号（Journal of General Virology）上，它凸显了研究植物疾病的重要性。
Varsani告诉本网站说：“我们的研究成果意味着DNA病毒比此前认为的进化速度更快。这种快速突变增加了新的植物病毒出现的可能性。”
南非传染病和分子医学研究所的Darren Martin领导了这项研究，他说：“尽管植物疾病并没有得到公众太多的关注，它们对粮食生产的影响导致的发展中国家的苦难比许多著名的人类疾病更多。”
研究植物疾病可以提供关于病原体的信息，后者可以用于培育抗病作物。今年早些时候，开普敦大学的研究组分析了至少200份被感染玉米的样本。本月将开始对来自布基纳法索、中非共和国、科特迪瓦、纳米比亚和津巴布韦的样本进行分析，结果将存入一个数据库。
开普敦大学分子和细胞生物学系的Dionne Shepherd正在负责培育能够抵抗这种条纹病毒的转基因玉米。
Shepherd告诉本网站说：“我们已经培育出了抗条纹病毒的玉米。如今我们需要证明它可以在整个撒哈拉以南非洲地区的不同环境下生长。”（生物谷Bioon.com）
生物谷推荐原始出处：
Journal of General Virology Published online ahead of print on 27 June 2008 as DOI 10.1099/vir.0.2008/003590-0
Recombination,decreased host specificity and increased mobility may have driven the emergence of maize streak virus as an agricultural pathogen
Arvind Varsani,Dionne N.Shepherd,Adérito L.Monjane,Betty E.Owor,Julia B.Erdmann,Edward P.Rybicki,Michel Peterschmitt,Rob W.Briddon,Peter G.Markham,Sunday Oluwafemi,Oliver P.Windram,Pierre Lefeuvre,Jean-Michel Lettand Darren P.Martin
Maize streak virus(MSV;family Geminiviridae,genus Mastrevirus),the causal agent of maize streak disease,ranks amongst the most serious biological threats to food security in subSaharan Africa.Although five distinct MSV strains have been currently described,only one of these–MSV-A–causes severe disease in maize.Due primarily to their not being an obvious threat to agriculture,very little is known about the‘grass-adapted’MSV strains,MSV-B,-C,-D and-E.Since comparing the genetic diversities,geographical distributions and natural host ranges of MSV-A with the other MSV strains could provide valuable information on the epidemiology,evolution and emergence of MSV-A,we carried out a phylogeographical analysis of MSVs found in uncultivated indigenous African grasses.Amongst the 83 new MSV genomes presented here,we report the discovery of six new MSV strains(MSV-F to -K).The non-random recombination breakpoint distributions detectable with these and other available mastrevirus sequences partially mirror those seen in begomoviruses,implying that the forces shaping these breakpoint patterns have been largely conserved since the earliest geminivirus ancestors.We present evidence that the ancestor of all MSV-A variants was the recombinant progeny of ancestral MSV-B and MSV-G/-F variants.While it remains unknown whether recombination influenced the emergence of MSV-A in maize,our discovery that MSV-A variants may both move between and become established in different regions of Africa with greater ease,and infect more grass species than other MSV strains,goes some way towards explaining why MSV-A is such a successful maize pathogen.
