Diallel analysis of barley for resistance to leaf stripe and impact of the disease on genetic variability for yield components |
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| Authors: | M I E Arabi |
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| Institution: | (1) Department of Molecular Biology and Biotechnology, Plant Pathology Division, AECS, P.O. Box 6091, Damascus, Syria |
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| Abstract: | Barley breeders in Syria attempting to develop barley (Hordeum vulgare L.) cultivars resistant to barley leaf stripe (BLS) disease caused by Pyrenophora graminea Ito & Kuribayashi anamorph Drechslera graminea (Rabenh. Ex. Schlech. Shoem.)]. Information on the combining ability for BLS resistance in Syria is not available. This study
was conducted to evaluate, in 10 genetically diverse barley parents, general combining ability (GCA) and specific combining
ability (SCA) effects towards the determination of the genetic basis of disease resistance and to estimate genetic variability
for yield components and its modification by BLS. Ten parental genotypes varying in their reactions to BLS were crossed in
a half-diallel mating design to generate 45 full-sib families. The families and the parents were inoculated with P. graminea and evaluated for resistance in replicated field tests (three inoculated and three non-inoculated plots). The parents chosen
showed wide variations for resistance to BLS. Genetic component analysis showed significant effects for both GCA and SCA for
resistance to BLS, suggesting that additive as well as non-additive genetic mechanisms were involved in the expression of
resistance in these parents. GCA effects were more important than SCA effects. Resistant parents exhibited high negative GCA
indicating that additive gene effects were more predominant, and suggesting their prime suitability for use in barley breeding
programs to improve resistance to BLS. Narrow-sense heritability was 58% and broad-sense heritability was 99% indicating that
selection for BLS resistance should be effective in these crosses. A high genetic variability for the agronomic traits studied
was observed. Yield components decreased significantly in inoculated plants and more pronounced in diseased plants. Significant
GCA was observed for all traits. Values for GCA were, in some cases, significantly modified by BLS. This indicates that attention
must be paid to the danger of drawing conclusion in quantitative genetics studies dealing with both diseased and healthy plants.
Two genotypes, Banteng and Igri, had high negative GCA effects and are promising parents for enhancement of BLS resistance. |
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| Keywords: | barley leaf stripe Drechslera graminea genetic resistance Hordeum vulgare Pyrenophora graminea |
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