TITLE:
Primed Expression of Defense-Related Genes by Streptomyces cameroonensis-Based Bioformulation (SCaB) on Cocoa Seedlings in a Nursery Challenged with Phytophthora megakarya
AUTHORS:
Dzelamonyuy Aristide, Téné Tayo Paul Martial, Alain Bopda Waffo, Effa Onomo Pierre, Ewané Cécile Annie, Boudjeko Thaddée
KEYWORDS:
Cocoa Seedlings, Phytophthora megakarya, Streptomyces cameroonensis, Bioformulation, Priming
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.14 No.12,
December
29,
2023
ABSTRACT: 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.