Pythium and Phytopythium species associated with hydroponically grown crops around the City of São Paulo, Brazil

Abstract

A survey of Pythium and Phytopythium species was conducted in hydroponics systems located in the metropolitan region of São Paulo and nearby cities, SP, Brazil. Different samples including water from artesian well, nutrient solution, substrates used for seedlings production and roots of hydroponically grown crops were collected and baited for Pythium and Phytopythium recovery. It was possible to isolate Pythium species from the four types of samples while Phytopythium species were isolated only from the substrates. The species were identified according to their morphological features and phylogenetic placement in a combined analysis of the ITS rDNA and COI mDNA regions within eight different taxa: Pythium kashmirense, P. middletonii, P. oopapillum, P. periplocum, P. segnitium, Pythium group F, Phytopythium helicoides and Phy. vexans. The isolates identified as Pythium group F were the most frequent species. While Pythium species were distributed in clades B, D and E, Phytopythium were distributed in clades 2 and 3. This study brings important information about the diversity of these species in hydroponic systems in Brazil and provides sequences of species rarely reported such as P. kashmirense, P. oopapillum and P. segnitium.