Research Article

**Variation and Heritability of Polyphenoloxidasic Activities in Two Hybrid Families of Theobroma cacao L. after Cocoa Pods Inoculation with Phytophtora megakarya Bras. et Grif.**

C. Simo, P.F. Djocgoue, H.D. Mbouobda, P.O. EFFA, T. Boudjeko and D.N. Omokolo

The black pod disease caused by P. megakarya is responsible for about 30% of cocoa production loss in Cameroon and Polyphenoloxidase (PPO), which contribute to plant resistance, were analysed in response to stress due to cocoa pod inoculation by mycelium of Phytophthora megakarya. Two cocoa plant (Theobroma cacao) hybrid families (F79: ♀T79/467 x ♂ SNK13; F13: ♀ SNK13x ♂ T79/467) were used in this study. Quantitative and qualitative analyses of the specific activities of PPO in the healthy, scarified and inoculated pods were realised in function of the productivity and the necrosis surface. Finally the study of the resistance transmission of PPO vis-à-vis P. megakarya from parents to offsprings was also performed. In the ionically bounded (I) fractions, the increase in the activities of PPO is correlated with tolerance rate of genotypes within the two hybrid families. Heritability of the reciprocal crossing of the PPO activities is higher for the (I) fractions (0.88 for F79 and 0.83 for F13) and do not show any significant difference for the two families suggesting the absence of a maternal effect. The use of PPO as a biochemical marker has permitted to reveal that the bonded PPO are more heritable than the soluble ones and these bonded PPO are seemingly good indicators of the resistance. Over all, the present study has enabled to classify the different groups of genotypes as tolerant and less tolerant and so, a large scale distribution of the tolerant and productive genotypes to cocoa farmers will be beneficial.

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C. Simo, P.F. Djocgoue, H.D. Mbouobda, P.O. EFFA, T. Boudjeko and D.N. Omokolo, 2011. Variation and Heritability of Polyphenoloxidasic Activities in Two Hybrid Families of Theobroma cacao L. after Cocoa Pods Inoculation with Phytophtora megakarya Bras. et Grif. Plant Pathology Journal, 10: 89-98.

DOI: 10.3923/ppj.2011.89.98

URL: https://scialert.net/abstract/?doi=ppj.2011.89.98

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Authors

C. Simo

P.F. Djocgoue

H.D. Mbouobda

P.O. EFFA

T. Boudjeko

D.N. Omokolo

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Research Article

**Variation and Heritability of Polyphenoloxidasic Activities in Two Hybrid Families of Theobroma cacao L. after Cocoa Pods Inoculation with Phytophtora megakarya Bras. et Grif.**

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