- Monday, June 1, 2009
- Published at:Journal of Al-Azhar University-Gaza (Natural Science)
- Eleven winter barley cultivars from Palestine screened for their resistance to powdery mildew in the field and under controlled conditions while, two types of resistance were identified. Three accessions showed low infection type (IT) at seedling stage with low disease severity (DS) in the mature plant. Six other lines showed low DS and low infection frequency (IF) with no macroscopically visible necrosis. These resistant accessions were selected and selfed for future studies.
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- Monday, January 26, 2009
- Published at:Not Found
- A set of 23 recombinant lines (RLs) of barley (Hordeum vulgare L.) derived from H. vulgare x H. bulbosum L. crosses was inoculated with barley leaf rust (Puccinia hordei) and powdery mildew (Blumeria graminis f.sp. hordei) at the seedling stage to identify their levels and mechanisms of resistance. Eight RLs were studied further in glasshouse and field tests. All three barley parents (Emir, Golden Promise and Vada) were highly susceptible to powdery mildew and leaf rust isolates. Several RLs showed partial resistance expressed as high relative latency periods and low relative infection frequencies against leaf rust. This high level of partial resistance was due to a very high level of early aborting colonies without host cell necrosis. Several RLs showed hypersensitive resistance to some or all isolates. For powdery mildew, one RL was completely resistant to the CC1 isolate and had a hypersensitive resistance to the CO-02 isolate. Three RLs derived from Emir were completely resistant to both powdery mildew is
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- Monday, January 26, 2009
- Published at:Not Found
- A population of 103 recombinant inbred lines (RILs, F9-derived lines) developed from the tworow spring barley cross L94בVada’ was evaluated under field conditions for resistance against powdery mildew (Blumeria graminis f.sp. hordei) and scald (Rhynchosporium secalis). Apart from the major resistance gene mlo on chromosome 4 (4H), three QTLs (Rbgq1, Rbgq2 and Rbgq3) for resistance against powdery mildew were detected on chromosomes 2 (2H), 3 (3H), and 7 (5H), respectively. Rbgq1 and Rbgq2 have not been reported before, and did not map to a chromosome region where a major gene for powdery mildew had been reported. Four QTLs (Rrsq1, Rrsq2, Rrsq3 and Rrsq4) for resistance against scald were detected on chromosomes 3 (3H), 4 (4H) and 6 (6H). All four mapped to places where QTLs for scald resistance had been reported before in different populations.
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- Monday, January 26, 2009
- Published at:Not Found
- A collection of 418 Spanish barley accessions was screened for resistance to leaf rust in the field at Córdoba, Spain during the 2002–2003 season. Six accessions displaying the lowest disease severity (DS) with no macroscopically visible necrosis were selected for further studies on components of resistance. Five of them showed a significantly higher relative latency period (RLP) than the susceptible line L94 and were similar to the partially resistant Vada. All of them showed lower relative infection frequency (RIF) and smaller colony size (CS) than the susceptible L94 under controlled conditions. Histological studies indicated that the resistance in four of these accessions was based on a higher percentage of early aborted colonies not associated with host cell necrosis. In the remaining two accessions resistance was based on hypersensitivity.
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- Monday, January 26, 2009
- Published at:Not Found
- A collection of 111 barley landraces from the Fertile Crescent was screened for resistance to barley leaf rust in the .eld and under controlled conditions. Large variation was observed for disease severity under .eld conditions. Accessions with high resistance because of hypersensitivity were identi.ed. Also segregation was observed in some accessions, with individual plants showing hypersensitive reactions (IT £ 6). Partial resistance due to a reduction of infection in spite of a compatible infection was commonly found (19%). Resistance of 12 accessions selected for their low disease severity and high IT, was shown to be due to a prolonged latency period and increased percentage of early aborted colonies not associated with host cell necrosis. A high correlation was observed between the microscopic and macroscopic components of partial resistance.
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RSS
Munqez Shtaya