تطور القدرة الإمراضية لفطر الصدأ الأصفر على القمح في سورية خلال موسم 2018-2019

الملخص EN

Wheat stripe (yellow) rust, caused by Puccinia striiformis f.

sp.

tritici Eriks.

and Henn, is the major disease problem in wheat production in most parts of Syria.

This study aimed to find out the current changes in the virulence of P.

striiformis f.sp tritici in Syria by identifying the prevalent physiological races and their virulence.

Surveys of wheat fields were carried out in four durum and bread wheat growing regions (Aleppo, El-Ghab, Homs, Costal area) during 2019.

A total of 55 samples ofP.

striiformis were collected.

Single pustules from each collection were multiplied on the susceptible cultivar Morocco.

Physiological races and their virulence were detected depending on the reaction type of Yr gene(s) which belong to Global/European differential set and near isogenic lines.

Ten physiological races were identified, five of them (230E130, 497E130, 231E134, 163E150 and 238 E234) were recorded for the first time in Syria, and the rest were recorded earlier during the period 2000-2017.

Races varied in their frequency and virulence.

All races spread in El-Ghab and Homs, some of them disappeared in Aleppo and Syrian costal region.

The most virulent races found in the study were 163E150, 230E134 and 238E234 (virulent up to 55 % of Yr genes), whereas the most frequent races 497E130, 462E136 and 230E150 showed a moderate negative correlation (-0.55) between the frequency ratio of races and their virulence r value.

The bulk of the pathogen population in 2019 was aggressive against 30 Yr gene(s) (1, 2, 3a, 3b, 4a, 4b,5, 6, 7, 8, 9, 9+, 10, 11, 12, 17, 18, 22, 23, 23V, 24, 26, 27, A, Ck, Cle, CV, H, H Peko, Nd, Sd, Su, Sp) at the seedling stage, and only Yr15 was completely effective against all physiologic races identified.

This gene is recommended for use by wheat breeders to improve the resistance for yellow rust in new wheat cultivars.

Efforts in the future are needed to identify novel resistance genes from wheat wild relatives.

Keywords: Wheat yellow rust, physiological races, Yr5, Yr15, Syria.