Resource seeking strategies of zoosporic true fungi in heterogeneous soil habitats at the microscale level

Abstract

Zoosporic true fungi have frequently been identified in samples from soil and freshwater ecosystems using baiting and molecular techniques. In fact some species can be components of the dominant groups of microorganisms in particular soil habitats. Yet these microorganisms have not yet been directly observed growing in soil ecosystems. Significant physical characteristics and features of the three-dimensional structures of soils which impact microorganisms at the microscale level are discussed. A thorough knowledge of soil structures is important for studying the distribution of assemblages of these fungi and understanding their ecological roles along spatial and temporal gradients. A number of specific adaptations and resource seeking strategies possibly give these fungi advantages over other groups of microorganisms in soil ecosystems. These include chemotactic zoospores, mechanisms for adhesion to substrates, rhizoids which can penetrate substrates in small spaces, structures which are resistant to environmental extremes, rapid growth rates and simple nutritional requirements. These adaptations are discussed in the context of the characteristics of soils ecosystems. Recent advances in instrumentation have led to the development of new and more precise methods for studying microorganisms in three-dimensional space. New molecular techniques have made identification of microbes possible in environmental samples.

Marine fungal communities in water and surface sediment of a sea cucumber farming system: habitat-differentiated distribution and nutrients driving succession

“…Chytridiomycota, Blastocladiomycota and Monoblepharidomycota) were found in sediment but not detected in water samples (Fig 5). Our results on zoosporic true fungi are in accordance with previous studies reporting their absence from, or low occurrence in, coastal waters (Wang and Johnson, 2009;Gao et al, 2010), marine sponges (Gao et al, 2008) and other aquatic ecosystems (Gleason et al, 2008(Gleason et al, , 2012a, but their frequent presence in estuarine or deep-sea sediments (Mohamed and Martiny, 2011;Nagahama et al, 2011). These observations suggest that the sediment could represent a suitable habitat, or "seed" bank, for these zoosporic true fungi.…”

Effects of damping-off caused by Rhizoctonia solani anastomosis group 2-1 on roots of wheat and oil seed rape quantified using X-ray Computed Tomography and real-time PCR

“…The effect of tillage on soil-borne pathogens in OSR has received less attention, however, it is likely that reduced or zero tillage maximizes disease and inoculum potential by allowing infected crop residues to remain on the soil surface and preserving hyphal networks in close proximity to the host ( Kharbanda and Tewari, 1996 ). Although soil structure can routinely be imaged at high resolutions (i.e., <100 μm), it is still not possible to visualize fungi per se using X-ray μCT due to their very low X-ray attenuation ( Gleason et al, 2012 ). However, indirect modeling approaches have been useful to aid understanding of the behavior and functioning of fungi in both real ( Pajor et al, 2010 ; Falconer et al, 2011 ) and artificial soil microstructures ( Otten et al, 2012 ).…”

A thready affair: linking fungal diversity and community dynamics to terrestrial decomposition processes

“…Until recently, it was believed that the basal Chytridiomycota were mainly aquatic and had virtually no importance for terrestrial ecosystem functioning. However, saprotrophic chytrids can dominate fungal communities in nonvegetated, high‐elevation soils (Freeman et al ., ), and their importance may also have been underestimated for other soils (Gleason et al ., ).…”