Out of the rivers: are some aquatic hyphomycetes plant endophytes?

Abstract

Pines would seem the most distinctive of trees, not least because of their signature needle-leaves. This homogeneity of form is paralleled by the sameness of their ecology: nearly all of the > 100 extant species of Pinus are light-demanding trees that act as long-lived pioneers on mesic sites, or as persistent components of the vegetation on harsher sites where there is little competition from other woody plants (Richardson, 1998). However, a new paper by Brodribb & Feild (this issue, showcases a remarkable departure from the familiar form and function of pines. Pinus krempfii Lecomte, a species with a restricted distribution in the montane tropical rainforests of southern Vietnam, is unique among extant pines in having flattened leaves instead of needles. Not only does P. krempfii look like a rainforest podocarp, it acts like one. Its seedlings are common under the rainforest canopy, and its photosynthetic physiology is typical of late-successional shade-tolerant trees. Brodribb & Feild show that this convergence of a pine on podocarp form and function is accompanied by the same vascular innovation found in broad-leaved Podocarpaceae: the development of large conductive sclereids that transport water away from the single leaf vein, through the mesophyll.Here I look briefly at the implications of these findings for questions about constraints on adaptive radiation in general, as well as for the biogeography of Pinus.

Fungal Growth and Biomass Development is Boosted by Plants in Snow-Covered Soil

“…The high abundance of this fungus in our mesh bag samples, therefore, shows for the first time that mycelia of aquatic hyphomycetes can saprobially grow in cold soil, preparing for abundant sporulation in spring as soon as melting water appears. The same Tetracladium was also detected in roots of three plant species at the study site [42][43][44], thus confirming the hypothesis that aquatic hyphomycetes have an endophytic stage [62].…”

Beyond the water column: aquatic hyphomycetes outside their preferred habitat

“…Several aquatic hyphomycete species reproduce sexually (first recorded by Ranzoni, 1956); their teleomorphs are typically produced on moist, but not submerged, twigs and branches, and teleospores are likely to be transmitted aerially as well as by water currents (Webster, 1992). In addition to dispersal of spores through perfect states, loose conidia on leaf surfaces or in foam cakes may escape as aerosol and be transported by wind or fog over extended distances to the foliar surfaces or other terrestrial substrata (Selosse et al, 2008). It is possible (though untested) that aerosols carry the conidia and redistribute them to substrata over a wide geographic area.…”

“…Possible mechanisms of transfer from/to live and dead plant tissues are illustrated. From Selosse et al (2008) with the permission of the New Phytologist.…”

“…Based on the phylogeny of the genus Tetracladium, where DNA sequences from endophytes and aquatic species intermingle, Selosse et al (2008) proposed that postulating dual endophytic and aquatic abilities in the common ancestor is the most parsimonious explanation. A similar, more comprehensive approach (Seena and Monroy, 2016) supports the same trend in many clades.…”

Molecular evidence reveals fungi associated within the epiphytic orchid Laelia speciosa (HBK) Schltr.

“…Fusarium solani is a widely distributed parasite that has been reported as an endophy- te in roots of the orchid Dendrobium nobile (Yuan et al, 2009). In case of species of the genus Tetracladium, usually they have been reported as aquatic hyphomycetes, however, they have been also found within plant tissues by cloning and sequencing (Selosse et al, 2008). Recently, sequences of 98% similar or higher with our Helotiales species have been found from multiple locations around the world.…”