Pataky J K, Plaisted D C, Scholten D, de Durand H F
Department of Crop Sciences, University of Illinois, Urbana 61801.
Rogers Seeds, 6338 Highway 20-26, Nampa, ID 83687.
Plant Dis. 2001 May;85(5):560. doi: 10.1094/PDIS.2001.85.5.560C.
The Rp1-D gene, which conveys a chlorotic-fleck resistant reaction to Puccinia sorghi, effectively controlled common rust on sweet corn in North America for nearly 15 years. Biotypes of P. sorghi virulent on plants with the Rp1-D gene were widespread in North America for the first time in 1999 and again in 2000 (1,2). Many Rp-resistant sweet corn hybrids that are developed and grown in North America also are grown in Europe, including France where virulence against the Rp1-D gene has not been reported previously. In September 2000, uredinia of common rust were observed on and collected from sweet corn hybrids with the Rp1-D gene in commercial fields and hybrid trials in the Landes and Pyrénées Atlantiques departments of the Aquitaine region of southwestern France. Severity of rust generally was below 5% on these plants except for a few hybrids for which severity was about 20 to 30%. Common rust was not observed on hybrids with the Rp-G gene. Urediniospores were increased as a bulk population on the susceptible sweet corn hybrid Sterling in a greenhouse. Plants with each of 10 single Rp genes (Rp1-A, Rp1-C, Rp1-D, Rp1-E, Rp1-F, Rp1-I, Rp1-K, Rp1-L, Rp1-N, and Rp-G) or each of six compound rust resistance genes (Rp1-D5, Rp1-JC, Rp1-JFC, Rp-GDJ, Rp-GFJ, and Rp-G5JC) were assayed for reactions to this population of P. sorghi. Two to six different sources of seed of each single Rp gene and two different sources of seed of each compound rust resistance gene were replicates with a single pot of 6 to 18 plants grown from a specific seed source. Plants were inoculated three times on successive days by placing 2 or 3 ml of a urediniospore suspension in the whorl of two- to four-leaved seedlings. Reactions were rated 10 days after the last inoculation. Plants without symptoms or with chlorotic-fleck resistant reactions were inoculated again and rated 10 days later. Uredinia did not form on plants with compound rust resistance genes. Plants with the genes Rp1-E, Rp1-I, Rp1-K, and Rp-G also were resistant although a few, very small uredinia (i.e., type-1 uredinia) were observed on a few plants. Plants with the genes Rp1-A, Rp1-C, Rp1-D, Rp1-F, Rp1-L, and Rp1-N were fully susceptible. This pattern of virulence is the same as that observed during the past two years in North American populations of P. sorghi virulent against Rp1-D. Rp-resistance currently available in most sweet corn hybrids will not be effective in France if these virulent biotypes become prevalent. References: (1) J. K. Pataky et al. Plant Dis. 85:165, 2001. (2) M. C. Pate et al. Plant Dis. 84:1154, 2000.
Rp1-D基因可使甜玉米对高粱柄锈菌产生抗褪绿斑点反应，在近15年里有效控制了北美的甜玉米普通锈病。1999年，对携带Rp1-D基因的植物具有毒性的高粱柄锈菌生物型首次在北美广泛出现，并于2000年再次出现（1,2）。许多在北美培育和种植的抗Rp基因甜玉米杂交种也在欧洲种植，包括法国，此前在法国尚未报道过对Rp1-D基因的毒性。2000年9月，在法国西南部阿基坦地区朗德省和比利牛斯-大西洋省的商业田地和杂交试验中，在携带Rp1-D基因的甜玉米杂交种上观察到并采集到了普通锈病的夏孢子堆。除了少数严重程度约为20%至30%的杂交种外，这些植株上锈病的严重程度一般低于5%。在携带Rp-G基因的杂交种上未观察到普通锈病。在温室中，将夏孢子堆大量接种到感病甜玉米杂交种Sterling上。对携带10个单一Rp基因（Rp1-A、Rp1-C、Rp1-D、Rp1-E、Rp1-F、Rp1-I、Rp1-K、Rp1-L、Rp1-N和Rp-G）或6个复合抗锈基因（Rp1-D5、Rp1-JC、Rp1-JFC、Rp-GDJ、Rp-GFJ和Rp-G5JC）的植株进行了对该高粱柄锈菌群体的反应测定。每个单一Rp基因有2至6个不同的种子来源，每个复合抗锈基因有2个不同的种子来源，以来自特定种子来源的6至18株植物种植在一个花盆中作为重复。通过在两叶至四叶期幼苗的叶腋中放置2或3毫升夏孢子悬浮液，连续三天对植株进行接种。在最后一次接种10天后对反应进行评级。对无症状或有抗褪绿斑点反应的植株再次接种，并在10天后进行评级。携带复合抗锈基因的植株上未形成夏孢子堆。携带Rp1-E、Rp1-I、Rp1-K和Rp-G基因的植株也具有抗性，尽管在少数植株上观察到了一些非常小的夏孢子堆（即1型夏孢子堆）。携带Rp1-A、Rp1-C、Rp1-D、Rp1-F、Rp1-L和Rp1-N基因的植株完全感病。这种毒性模式与过去两年在北美对Rp1-D具有毒性的高粱柄锈菌群体中观察到的模式相同。如果这些毒性生物型变得普遍，目前大多数甜玉米杂交种中可用的Rp抗性在法国将无效。参考文献：（1）J.K.帕塔基等人，《植物病害》85:165，2001年。（2）M.C.佩特等人，《植物病害》84:1154，2000年。
