Mawere S, Vincent V, De Meyer J, Pixley K V
International Maize and Wheat Improvement Center (CIMMYT), P.O. Box MP163, Mount Pleasant, Harare, Zimbabwe.
Former Visiting Scientist to CIMMYT (Zimbabwe).
Plant Dis. 2006 Dec;90(12):1485-1489. doi: 10.1094/PD-90-1485.
Maize streak is the most widespread and important disease of maize in sub-Saharan Africa. Maize streak virus (MSV)-resistant maize germ plasm is available in several countries, but little is known about the stability of its resistance to MSV strains that may differ from one region to another. We used four maize inbred lines (CML312, CML206, CML216, and MSR) known to differ widely for their resistance to MSV in Harare, and evaluated their resistance to 20 MSV isolates collected from the wild during 2 years at locations across Zimbabwe. Maize streak development and symptom severity were evaluated in replicated greenhouse experiments using artificial inoculation via viruliferous leafhoppers. All 20 MSV isolates induced maize streak symptoms on moderately and highly susceptible genotypes by about 1 week after inoculation (WAI). Differences among isolates for severity of early maize streak symptoms were ephemeral, and resistance was accurately differentiated by all isolates by 3 to 4 WAI. Differences in final maize streak symptom scores induced by the isolates were statistically significant, but differed only by a maximum of 7% in 1999 and 19% in 2000. Although genotype, isolate, and genotype by isolate effects for maize streak symptom scores were significant (P < 0.01), relative MSV resistance of the genotypes was consistently ranked by all 20 MSV isolates.
玉米条纹病是撒哈拉以南非洲地区分布最广且最重要的玉米病害。几个国家都有抗玉米条纹病毒（MSV）的玉米种质，但对于其对不同地区可能存在差异的MSV株系抗性稳定性了解甚少。我们在哈拉雷使用了四个已知对MSV抗性差异很大的玉米自交系（CML312、CML206、CML216和MSR），并在两年时间里于津巴布韦各地对它们对从野外收集的20个MSV分离株的抗性进行了评估。在重复的温室试验中，通过带毒叶蝉人工接种来评估玉米条纹病的发展和症状严重程度。所有20个MSV分离株在接种后约1周（WAI）在中度和高度易感基因型上诱发了玉米条纹症状。分离株之间早期玉米条纹症状严重程度的差异是短暂的，到3至4 WAI时所有分离株都能准确区分抗性。分离株诱发的最终玉米条纹症状评分差异具有统计学意义，但在1999年最大差异仅为7%，在2000年为19%。尽管玉米条纹症状评分的基因型、分离株以及基因型与分离株的交互作用显著（P < 0.01），但所有20个MSV分离株对基因型的相对MSV抗性排序一致。
