السلالات الفيزيولوجية و القدرة الامراضية لفطر الصدأ الأصفر على القمح Puccinia striiformis f. sp. tritici Eriks. في سورية و لبنان

Abstract EN

The objectives of this study were to monitor the population of the physiological races of Wheat Yellow Rust Puccinia striiformis West.

f.

sp.

tritici Eriks and their virulences in Syria and Lebanon and the identification of prevailing physiological races and their virulence during four seasons (1996/97, 1997/98, 1998/99, 1999/2000).

The study included planting the differential cultivars under field conditions at Tel-Hadya in Syria and Terbol in Lebanon and under controlled condition at Tel-Hadya (ICARDA) research station.

The field data showed ineffectiveness of the following Yr genes (Yr7, Yr6, Yr10, YrSD, Yrsu, Yr9+, Yr6+, Yr7+, Yr2+ , YrA, Yr2, Yr9, Yr17 ,and Yr18) in Syria and Lebanon.

So far the population of the physiological races in Lebanon were recognized by their ability to overcome the 3V gene which is still effective in Syria.

Results under controlled conditions showed that eighteen yellow rust races (2E0, 6E0, 6E16, 6E18, 6E20, 6E134, 20E148, 38E0, 38E6, 38E134, 38E150, 82E16, 134E134, 134E146, 230E134, 230E150, 68E130, 70E130) were present in Syria and eleven (6E0, 6E134, 38E22, 38E134, 134E150, 230E150, 166E150, 172E146, 182E150, 70E148, 198E150) in Lebanon.

Some of these races were found in both countries (6E0, 6E134, 38E134, 230E150) and some of them were found only in one country (172E146, 182E150).

In general, the data showed that some of the races are frequently present in the yellow rust population in Syria and Lebanon and some of them are new identified races (6E20, 38E6, 38E0, 68E130, 70E130, 134E134, 230E150) in Syria and (198E150, 230E150) in Lebanon.

The study indicated that variation in virulence among the races exist, where 2E0 was the weakest race in Syria and could overcome only one resistance gene Yr7; the race 230E150 was the most virulent race which can overcome fourteen resistance genes (Yr6, Yr7, YrSD, Yrsu, Yr9+,Yr7+ ,Yr6+, Yr8, Yr2+, YrA, Yr2, Yr9, Yr17 and Yr18).