Syzygites echinocarpus is widely considered to be a mycoparasite and is commonly found on decaying Basidiomycetes and some Ascomycetes. Water has little effect on Syzygites echinocarpus’ ability to form sexual reproduction. However, it does appear that light has some impact on the formation of sporangiophores, Syzygites echinocarpus rarely forms sproangiophores in complete darkness. Scientists have interpreted these results to indicate that the zygosporic stage is the resistant stage in Syzygites echinocarpus’ life cycle (6).
Syzygites echinocarpus is considered to be a necrotrophic mycoparasite that infects a wide host range. It is a real problem in the exportation of expensive edible mushrooms (such as Tricholomas). Syzygites echinocarpus first infects the pileus of the sporocarp then spreads to the surrounding tissue (7). During infection Syzygites echinocarpus forms a macro-mycelial structure which can be yellow, blue, or gray in color (8).Due to its wide host range Syzygites echinocarpus has a relatively large ecological distribution. Syzygites echinocarpus have been found in wetlands, lawns, and woodland habitats (9).
In natureS. megalocarpusis parasitic on Basidiomycetes and a few Ascomycetes (Kovacs and Sundberg, 1999). Benny and O’Donnell (1978) described the ontogeny of sporangia, sporangiospores, and zygospores using light microscopy. The ontogeny of the zygosporogenesis, mainly using electron microscopy, inS. megalocarpuswas presented by O’Donnell (1979).Syzygites megalocarpusis unusual in its formation of sporangiospores with spinose walls, a characteristic also shared bySporodiniella umbellata(Ekpo and Young, 1979)(Zygomycetes.org 2007)
Unlike most members of the Mucorales order, Syzygites echinocarpus is a homothallic species.The sporangia of Syzygites echinocarpus form directly on decaying Basidiomycetes (3).Sporangiophores stand erect. These structures are regularly septate and dichotomously branched (4), Figure 3. The sporangium contains a columella and only a few spores. The overall appearance of the sporangium is globose. The sporangiospores contain a spiny wall and are round in shape (3).
Syzygites echinocarpus is very important to humans economically. Syzygites echinocarpus has the ability to infect most edible mushrooms. This means that this fungus can have a large impact on the food industry worldwide. However, Syzygites echinocarpus has heightened importance in Asian countries because it is a parasite of Tricholomas. This type of Basidiomycete is extremely popular in Asian cuisine and it is very expensive.Due to the harmful, necrotrophic, effects of a Syzygites echinocarpus infection the Asian food market is particularly concerned with this zygomycete (8).
However mushroom farmers worldwide are concerned about Syzygites echinocarpus. Since it can infect a wide variety of fleshy mushrooms there is worldwide concern that a large infection could debilitate the worldwide supply of edible, commercially shipped mushrooms (9).
Syzygites echinocarpuscan be identified based upon morphology of its macrostructure during mycoparasitism. Syzygites echinocarpus infects sporocarps of a variety of hosts. During infection Syzygites echinocarpus forms a mycelial structure, which is furry or fuzzy looking, Figure 2. This fuzzy structure can appear yellow, blue or gray (8).
The sexual reproduction of Syzygite echinocarpus is homothallic, unlike most other species in the Mucoraceae family.In zygospore formation the zygophores can arise by 3 different mechanisms. The first mechanism occurs when a lateral branch forms off of the main hypae. This branch dichotomizes near its origin forming 2 branchlets (zygophores) which then undergo sexual reproduction. The second mechanism, which is the most common mechanism for zygospore formation, occurs when 2 zygophoric branches form close together directly from the hypha. The final mechanism occurs when zygophores forms on different threads of hypha, rather than close together on the same hyphae, and undergo sexual reproduction (6).
Suspensor cells of Syzygite echinocarpus are equally sized (3) and form parallel to zygospore and highly swollen (1), Figure 4. Zygospores have ornamented walls (3).
The fungi Syzygites echinocarpus is a member of the subphylum Mucoromycotina, the order Mucorales, and the family Mucoraceae. The genus Syzygites was first described by Ehrenberg in 1818 due to the unique zygosporic stage of the genus. In 1863 a synonym of the species Syzygites echinocarpus was described by Hildebrand, this synonymous fugal species was named Hildebrandiella echinocarpa (1). Some research has suggested that Syzygites megalocarpus is a synonymous species to Syzygites echinocarpus, however this synonymous relationship is somewhat controversial and has not been confirmed by DNA data in multiple studies. Syzygites echinocarpus does not have a common name.
The genus Syzygites has been researched using phylogenetic studies on several occasions. Through these studies it has been determined that Syzygites are most closely related to Rhizopus stolonifer (2) Figure 1.
Syzygitessporangiophores arise directly from the substrate. They are several times dichotomously branched with each branch terminating in a sporangium that is globose, columellate, and few-spored; wall deliquescent. Sporangiospores globose, with a spinose wall. Zygospores with a pigmented, ornamented wall; formed on a more or less equal, opposed suspensors. Zygospores formed on dichotomously branched zygophores terminating in sterile spines (Hesseltine, 1957).
Type species:S. megalocarpus