Variability in reproductive morphology of family Saprolegniaceae and its significance

Description of Saprolegnia velencensis sp. n. (Oomycota), a novel water mold species from Lake Velence, Hungary

“…The temperature tolerance of most Saprolegnia species is usually wide [ 6 , 37 , 43 ], and saprolegniosis may occur both in cold and warm water [ 2 , 6 ], although the most intense hyphal growth has been observed at RT, under in vitro conditions [ 6 , 43 ]. Our observation was that immature oogonia were mostly produced in the presence of fish skin extract, in contrast to a previous conclusion suggesting that sexual reproduction of water molds usually occurs under nutrient-depleted conditions [ 14 , 44 ]. Moreover, the thinning of hyphae and the abundance of gemmae and gemma chains in distilled water (SDW) suggest that the new species responded to the nutrient-poor environment by producing persistent vegetative structures.…”

“…Moreover, some species such as S. parasitica, often fail to produce sexual reproductive structures (i.e. oogonia and antheridia) in vitro, which would be necessary for the morphology-based identification [5,10,14]. Some studies have suggested that changing favorable and unfavorable conditions can induce the production of sexual reproductive structures of Saprolegnia strains in vitro, however it could not be applied successfully in every case [11,[15][16][17].…”

New Insights into the Morphological Diversity of Saprolegnia parasitica (Oomycota) Strains under In Vitro Culture Conditions

“…A gemma is a vegetative structure that provides-among other things-the survival of water molds under unfavorable conditions [3,29,30]. Conversely, some authors reported that a nutrient-rich condition might also induce gemma formation [3,10]. Gemmae can have various shapes and are able to form chains of different lengths, as shown in our study.…”

“…Previous studies concluded that the formation of reproductive structures is favored in a nutrient-poor environment under laboratory conditions [10][11][12]. Their concept is that the lack of proper nutrition is a stress factor and the reproduction of water molds is initiated as a reaction to environmental stress, which sounds reasonable.…”

“…However, notable achievements were reached in this matter when researchers managed to induce the formation of asexual and sexual reproductive structures under different laboratory conditions [7][8][9]. A common view is that the sexual reproductive structures (i.e., oogonia and antheridia) are formed under unfavorable conditions in vitro [10][11][12]. On the other hand, depending on the environmental conditions, oogonia and antheridia may be rare or even absent in in vitro cultures, as others have found [7,8].…”