McVey D V, Nazim M, Leonard K J, Long D L
United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Cereal Disease Laboratory, St. Paul, MN 55108.
Faculty of Agriculture, Minufiya University, Shibin el-Kom, Egypt.
Plant Dis. 2004 Mar;88(3):271-279. doi: 10.1094/PDIS.2004.88.3.271.
Frequent epidemics of leaf rust in Egypt have been attributed to the appearance of new races virulent on commonly grown wheat cultivars. In 1998, 1999, and 2000, 726 isolates of Puccinia triticina collected in Egypt were tested on a set of 20 single Lr gene differential wheat lines, and 160 races were identified. Three races, MBDLQ, MCDLQ, and TCDMQ, were found in Egypt in all 3 years. Race MCDLQ occurred at >20% frequency each year. Virulences to wheat lines with Lr1, 3, 10, 14b, 15, 17, 23, and 26 occurred at >45% each year. Seven races found in Egypt also were found in either Israel, Sudan, Turkey, or Romania in 1998 or 1999, although the one race common to Sudan and Egypt was rare in Egypt (only 1 year, <1%). Four races found in Israel also were found in Egypt, and the similarity of virulence frequencies in Israel and Egypt indicate at least some exchange of inoculum. Romania and Turkey did not appear to be major sources of inoculum for leaf rust epidemics in Egypt. The level of genetic diversity in leaf rust collections in Egypt in 1998 to 2000 was similar to that of collections from the Southern and Central Plains of the United States in 1998 to 2000. The high diversity of races and the recurrence of common races in each year in Egypt as in the Southern and Central Plains of the United States is consistent with oversummer survival of P. triticina within Egypt or in a neighboring country. The buildup of races virulent on cultivars with the most commonly used Lr genes for resistance in Egypt also is consistent with year-round survival within Egypt or cyclical exchange of inoculum between Egypt and a neighboring country.
埃及叶锈病频繁流行被认为是出现了对常见种植小麦品种具有毒性的新小种所致。1998年、1999年和2000年，对在埃及收集的726个小麦叶锈菌分离株在一套20个携带单个Lr基因的小麦鉴别系上进行了测试，共鉴定出160个小种。在这3年中，埃及均发现了3个小种，即MBDLQ、MCDLQ和TCDMQ。小种MCDLQ每年出现频率均超过20%。对携带Lr1、3、10、14b、15、17、23和26基因的小麦系的毒性每年出现频率均超过45%。1998年或1999年在埃及发现的7个小种在以色列、苏丹、土耳其或罗马尼亚也有发现，不过苏丹和埃及共有的那个小种在埃及很罕见（仅出现1年，频率<1%）。在以色列发现的4个小种在埃及也有发现，以色列和埃及毒性频率的相似性表明至少有一些接种体的交换。罗马尼亚和土耳其似乎不是埃及叶锈病流行的主要接种体来源。1998年至2000年埃及叶锈菌样本的遗传多样性水平与1998年至2000年美国南部和中部平原样本的遗传多样性水平相似。埃及小种的高度多样性以及每年常见小种的重现，与美国南部和中部平原一样，这与小麦叶锈菌在埃及境内或邻国越夏存活是一致的。在埃及，对具有最常用抗锈Lr基因的品种具有毒性的小种的积累，也与在埃及境内全年存活或埃及与邻国之间接种体的周期性交换是一致的。
