Author(s)

Dzelamonyuy Aristide^1,2, Téné Tayo Paul Martial^1*, Alain Bopda Waffo², Effa Onomo Pierre^1,3,4, Ewané Cécile Annie^1,3,4*, Boudjeko Thaddée^1,3+

¹Laboratory of Phytoprotection and Valorization of Genetic Resources, Biotechnology Center, University of Yaounde I, Yaounde, Cameroon.
²Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA.
³Department of Biochemistry, Faculty of Science, University of Yaounde 1, Yaounde, Cameroon.
⁴Laboratory of Plant Physiology, Department of Biological Sciences, Higher Teacher’s Training College, Yaounde, Cameroon.

A Streptomyces cameroonensis based bioformulation (SCaB) has been developed and shown to be stable and effective in controlling the early proliferation of P. megakarya and promoting the growth of cocoa seedlings in nursery. This study was carried out to explore the molecular mechanisms associated with the interaction of SCaB, cocoa seedlings, and the pathogen during the early stages of seedling growth in the nursery. For this purpose, seedling treatment with 10% W/W SCaB under greenhouse conditions evaluated SCaB’s capacity to stimulate the defense mechanisms in cocoa. Agronomic growth parameters and the level of induction of defense-associated compounds were analyzed. Real-time (rt) PCR was used to assess the level of expression of defense genes. Here, we showed that the application of SCaB as a seedling treatment enhanced the growth of cocoa seedlings in the nursery by an average of 15.6% after 30 days of growth and led to an average reduction in disease severity of 64% when challenged with P. megakarya. The latter led to an increased synthesis of total phenolic compounds, flavonoids, chitinases, peroxidases, and β-1,3-glucanases and an induced up-regulation of TcChiB, TcGlu-1, TcPer-1, and TcMYBPA genes. This research provides a basis for the optimization of beneficial microorganisms as a viable alternative to chemical fungicides used in disease suppression.

Cocoa Seedlings, Phytophthora megakarya, Streptomyces cameroonensis, Bioformulation, Priming

Aristide, D. , Martial, T. , Waffo, A. , Pierre, E. , Annie, E. and Thaddée, B. (2023) Primed Expression of Defense-Related Genes by Streptomyces cameroonensis-Based Bioformulation (SCaB) on Cocoa Seedlings in a Nursery Challenged with Phytophthora megakarya. American Journal of Plant Sciences, 14, 1480-1497. doi: 10.4236/ajps.2023.1412100.