twentyfourteen domain was triggered too early. This is usually an indicator for some code in the plugin or theme running too early. Translations should be loaded at the init action or later. Please see Debugging in WordPress for more information. (This message was added in version 6.7.0.) in /var/www/vhosts/gcsar.gov.sy/httpdocs/en/wp-includes/functions.php on line 6131Mayada Alaa Kayali Abstract<\/strong><\/p>\n Wheat is infected by many diseases that vary in severity and incidence\u00a0 according to prevalent climate conditions in cultivation areas. Common bunt (CB) caused by Tilletia caries and T. foetida, remains a serious and dangerous wheat disease in Syria. It affects most types of durum and bread wheat cultivated in the world, causing losses in grain yield. Given the importance of this strategic crop and the relative lack of studies on this disease in Syria, particularly in terms of prevalence, incidence, pathotypes, and genetic resistance, this study aimed to: (1) determine the occurrence of common bunt at major wheat growing areas in Syria; (2) study the pathogen variability (Tilletia caries and T. foetida) according to climatic variation in Syria;\u00a0 (3) characterize pathogen races and resistant genes according to reaction on differential varieties under Syrian conditions; (4)\u00a0 Molecular Characterization of T. caries and T. foetida races using the AFLP tool; and (5) evaluate and select durum and bread wheat accessions for resistance to common bunt. Mayada Alaa Kayali General Commission for Scientific Agriculture Research- Aleppo Research Center Faculty of Agriculture, Aleppo University 2010 Abstract Wheat is infected by many diseases that vary in severity and incidence\u00a0 according to prevalent climate conditions in cultivation areas. Common bunt (CB) caused by Tilletia caries and T. foetida, remains a serious and dangerous wheat … Continue reading Common Bunt of Wheat and Genetic Variability within Tilletia spp. in Syria<\/span>
\n<\/strong>General Commission for Scientific Agriculture Research-
\n<\/strong>Aleppo Research Center
\n<\/strong>Faculty of Agriculture, Aleppo University
\n<\/strong>2010<\/strong><\/p>\n
\nField surveys were carried out in main wheat growing governorates during 2006 and 2007, covering 220 and 151 durum, 119 and 80 bread wheat fields, respectively. The results revealed presence of significant differences in disease incidence in the surveyed fields. The highest infection rate was recorded in first season at Idleb on durum (14.5%) and bread wheat (32.2%), whereas the lowest infection rate was obtained in Deraa (3.8 and 8.8% respectively). In the second season, a highest infection rate was recorded in Aleppo 15.5 and 25.1% on durum and bread wheat, respectively, while the lowest infection was recorded\u00a0 in Hassakeh, on durum wheat (3.7%). The results also showed\u00a0 that both pathogens\u00a0 (T. caries and T. foetida) were found on wheat at all surveyed\u00a0 provinces, with variation in host-preference. Mean frequencies of\u00a0 T. caries and T. foetida\u00a0 teliospores during 2006 and 2007 in durum were (84.6, 15.4 and 88.8, 11.2%), where that relationship was approximately 8:1 and 6:1, respectively, and (19.4, 80.6 % and 16.7, 83.3 %) in bread wheat and a relationship of 1:4 and 1:5, respectively.
\nPathogenicity tests of 29 combinations (mixtures) of\u00a0 T .caries and T. foetida (1:1 w:w) teliospores, collected from the different\u00a0 surveyed\u00a0 fields, were conducted\u00a0 under artificial infection, on four durum and four bread wheat cultivars with different reaction types against the disease: very susceptible (VS), susceptible (S), moderate resistant (MR), and resistant. The results revealed presence of variations in percentages of infected plants according to inoculum combinations, that ranged between 10 – 43.6% on the VS durum cultivar, and 26 – 80% on the VS bread wheat cultivar. Accordingly, the combination pathogenicity of both pathogens was divided into 3 levels: weak, moderate and highly virulent.
\nReaction of tested differential varieties against 27 bunt isolates (15 T .caries and\u00a0\u00a0 12 T. foetida), collected in 2007. Four Isolates (A5, A6, A9 and A10) overcome the resistant genes Bt0 and Bt7, and were designated as race T-1. Also, seven isolates (H11, H12, H13, H14, K20, K21 and K22) defeated the resistant genes Bt0, Bt2 and Bt3, and were designated as race T-11; two other isolates (H15 and Da16) defeated resistant genes Bt7, Bt1 and Bt0, and were called race L-4. Finally, five isolates (A3, A4, A5, A7 and A8) defeated the resistant genes Bt0, Bt1, Bt2 and Bt3, and were designated as race L-9.
\nAs far as the rest of isolates, they were not similar in their interaction with known universal differential varieties, and are therefore considered as new races\u00a0 and were given new codes. Isolates that broke down the resistance genes Bt0, Bt2, Bt3, Bt4, Bt6, Bt7, Bt13, Bt14, Bt15 and Bp, named as races L-13 and T-17; isolates that defeated\u00a0 resistance genes Bt0, Bt7, Bt13, Bt14, Bt15 and Bp, were named races L-14 and T-18, and the isolate that broke down the resistance genes Bt13, Bt14 and Bt15, were named race L-15.
\nCollected bunt isolates during 2007 are divided, according to their pathogenicity into three groups:
\nGroup I= weakly virulent: including 7 isolates (H15, K21, K23, K24, K25, K26 and K27).
\nGroup II= moderately virulent: including 12 isolates (A1, A3, A4, A9, A10, H12, H14, Da16, Da18 Da19, K20 and K22).
\nGroup III= highly virulent: includes 8 isolates (A2, A5, A6, A7, A8, H11, H13 and Da17).
\nStatistical analysis showed positive significant correlation between the average height reduction of wheat plant and virulence degree of isolate, where r value increased proportionally with isolate virulence\u00a0 (r = +0.79, +0.96 and +0.77 for groups I, II and III, respectively).
\nThe cluster scheme of pathogenicity\u00a0 determines the degree of kinship between tested isolates, which were distributed in two groups, from different geographical areas:
\nGroup I included 12 isolates, 4 moderately virulent and 8 highly virulent (A2, A4, A5, A6, A7, A8, H11, H12, H13, H14, Da17 and Da18).
\nGroup II: included 15 isolates, 7 weakly virulent and 8 moderately virulent (A1, A3, A9, A10, H15, Da16, Da19, K20, K21, K22, K23, K24, K25, K26 and K27).
\nThe AFLP technique showed low genetic variation of the fungal pathogen between sites (15%), but was high within the same site (85%).
\nSYSTAT cluster analysis jointly with PCA analysis determined the genetic relationship between the studied isolates; it divided the isolates of both pathogens into four main groups. The results show isolate similarity despite the geographical divergence (Hama \/ Deraa, Tunisia \/ Hassakeh, and Tunisia \/ Deraa isolates). This may be due to the transfer of infected seed from one region to another. However, other isolates collected from one site appeared in different groups.
\nSeed of 104 durum and 102 bread wheat genotypes were screened in 2006\/07 and 2007\/08 seasons, under artificial inoculation using a mixture of teliospores of both Tilletia caries and T. foetida under\u00a0 field conditions. Significant variations in reaction types were found in infected plants. In the first season, 12 durum and 4 bread wheat genotypes showed resistant reaction (R) to the disease, and\u00a0 23 durum and 4 bread genotypes reacted moderately resistant (MR). Only 8 tested durum genotypes were resistant in the second season, meanwhile 24 tested durum and 10 bread wheat genotypes proved moderately resistant (MR). The resistant genotypes could be used in breeding programs for increasing resistance of high yielding-wheat cultivars.<\/p>\n","protected":false},"excerpt":{"rendered":"