First Report of Phytopythium vexans (de Barry) Abad, de Cock, Bala, Robideau, Lodhi & Lévesque Causing Potato Tuber Rot in Indonesia

Abstract

Phytopythium vexans (de Barry) Abad, de Cock, Bala, Robideau, Lodhi & Lévesque was successfully isolated from the soil of the potatoes field in Ngablak, Magelang. This research aimed to obtain the knowledge and potency of P. vexans as a pathogen in potatoes, identify the morphology and molecular of P. vexans compared with the Oomycetes, Phytophthora and Pythium. The morphological observation was conducted based on a macroscopic colony pattern that grew for five days on the PDA medium and microscopic observation on its hyphae, sporangia, papillate, and chlamydospore. The molecular identification was conducted using multigene analysis, ITS and LSU. The in vitro pathogenicity test was obtained by inoculating P. vexans inoculum to the healthy potatoes leaves and tubers. The results of morphological observation showed that P. vexans had a stellate pattern, aseptate hyphae, and sporangium with an ovoid shape completed with semipapillate. Chlamydospore as a survival form was also found. This research revealed that the morphology of P. vexans was between Pythium and Phytophthora. Whereas, based on the molecular analysis using ITS and LSU, the Phytopythium spp. are more closely related to Phytophthora spp. rather than Pythium spp. The pathogenicity test of P. vexans showed that it could infect the flesh of potato tubers showing a brown lesions symptom