Epistasis and heritability of resistance to <Emphasis Type="Italic">Phytophthora nicotianae</Emphasis> in pepper (<Emphasis Type="Italic">Capsicum annuum</Emphasis> L.) |
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Authors: | F Bnejdi M Saadoun M B Allagui M El Gazzah |
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Institution: | (1) Laboratoire de génétique et biométrie faculté des sciences de Tunis, Université Tunis El Manar, Tunis, Tunisia;(2) Institut National de la Recherche Agronomique de Tunisie (INRAT), Rue Hedi Karray, 2049 Ariana, Tunis, Tunisia |
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Abstract: | Gene effects of resistance to two isolates of Phytophthora
nicotianae in two crosses of pepper were investigated using separate generation means analysis. Additive-dominance models were inadequate
in all cases. Digenic parameter models were adequate in three cases and the probability of goodness of fit of models was negatively
correlated with the aggressiveness of the pathogen. None of these models explained variation among generation means in the
combined cross Beldi × CM334 with P.
nicotianae isolate Pn2. Additive × additive, dominance × dominance and dominance × additive effects were significant in most cases. Additive and
dominance effects (of negative sign) contribute more to resistance than to susceptibility. Additive variance was greater than
environmental and dominance variance and ranged from 0.038 to 0.224. Narrow-sense heritabilities were dependent upon the cross
and inoculate and ranged from 86 to 92%. The results of this study indicate that selection with more aggressive isolates of
the pathogen will be useful for enhancing resistance in pepper. |
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Keywords: | Epistasis Additive-dominance model Best-fit model Aggressiveness Phytophthora nicotianae Pepper |
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