Phytophthora blight, caused by Phytophthora capsici, is one of the most destructive soil-borne pathogen in the korea and worldwide. Phytophthora blight have severe effects on the roots, stems, leaves, and fruit of red-peppers, depending on the growth stage at infections. Zoospores of Phytophthora capsici can be easily dispersed across a field by rain and irrigation. Because of these higher vulnerability of plants, preventing Phytophthora capsici living in soil by conventional chemical pesticides are very challengeable, and biocontrol using beneficial microorganisms is recently considered as one of the promising approaches for controling severe soil borne diseases.
Trichoderma harzianum is one of rhizosphere fungus, generally associated near the plant root regions in the soil. It has been well characterized that T. harzianum plays an important role in plant growth promotion and increased disease resistance against various plant pathogens on crops. However, the molecular mechanisms of how the beneficial soil fungus, Trichoderma harzianum could enhance plant growth promotion and immune responses is largely unknown. In this study, the strain T. harzianum MPA167 was isolated from the barley rhizosphere soil in Suwon, Korea. 183 microorganisms were isolated from the soil samples. Among 183 isolates, the strain T. harzianum MPA167 was selected as a promising strain, because of its suppression of mycelial growth against Phytophthora capsici in vitro and in vivo. The strain of T. harzianum MPA167 was identified via 5.8s rRNA Internal Transcribed Spacer(ITS) Region sequences. Trichoderma inoculation to pepper plants (1×106 spores/ml) showed greater disease suppression against Phytophthora capsici on red-pepper plant in greenhouse compared with the water-treated control. Volatiles derived from T. harzianum MPA167 would be contributed to growth promotion of tobacco and Arabidopsis seedlings. Furthermore, T. harzianum MPA167 strain was affected to the enhancement of not only the plant growth promotion, but also immunity via induced systemic resistance (ISR) on red-papper plant. Conditionally the selected strain of T. harzianum MPA167 could be a potential biocontrol agent against plant diseases including phytophthora blight of red-pepper plants.