Interaction dynamics between endophytic biocontrol agents and pathogen in the host plant studied via quantitative real-time polymerase chain reaction (qPCR) approach

The interaction dynamics between endophytic biocontrol agents and pathogens were investigated to determine their co-existence in the host plant. The endophytes (Diaporthe phaseolorum WAA02, Trichoderma asperellum T2, Penicillium citrinum BTF08) and pathogen (Ganoderma boninense Gb) were inoculated into oil palm ramets and their relative abundance in root, stem and leaf tissues was assessed via quantitative real-time PCR. This was done using single inoculations (for every endophyte and pathogen) and co-inoculations (combined inoculation of every endophyte with Gb). In single inoculations, BTF08 (P. citrinum) was the most abundant in the host tissues (3.93 × 10¹⁸ ng/mg DNA concentration), followed by WAA02 (D. phaseolorum) and T2 (T. asperellum) (1.30 × 10³ and 6.48 × 10¹ ng/mg, respectively). Pathogenic Gb was the least abundant (1.58 × 10¹ ng/mg). When co-inoculated with Gb, all endophytic isolates outcompete Gb suggesting superiority of endophytic isolates when in co-existence with Gb. All isolates favoured colonization in stem tissues (0.024–4.84 × 10¹⁷ ng/mg), followed by root (0.045–7.30 × 10¹⁵ ng/mg) and leaf tissues (0.072–1.16 × 10⁴ ng/mg). This study represents the first report on the simultaneous monitoring of pathogen and endophytic BCA in a host plant model via real-time PCR.