Chapter 8
Micromorphological Features of Sclerotia
Grains
Makiko Watanabe and Akira Genseki
Abstract The micromorphological features of the interiors of sclerotia grains were
examined by scanning electron microscopy and transmission electron microscopy
combined with energy-dispersive X-ray (SEM-EDX, TEM-EDX) and micro computed tomography (micro-CT) analyses. Spherical particles with a diameter of
100 nm were found inside sclerotia grains and were found to be composed predominantly of carbon and aluminum, suggesting that they are melanin-like particles.
Spherical acicular structures, determined to be boehmite by TEM-EDX analysis,
were commonly observed by SEM in the center of sclerotia grains. In addition to
such aluminum polymorphs, aluminum sulfates and silicon spherical structures,
identified as opaline silica, were observed inside sclerotia grains. A graphene-like
fraction was observed in the center of sclerotia grains, near titanium oxides or small
amounts of adhering calcium, magnesium, or iron oxides. Micro-CT analysis of
intact sclerotia grains clearly showed the presence of mycelial strands, that were
confined to the interior of the grain.
Keywords Sclerotium grain · Melanin-like particles · Boehmite · Graphite · Opaline
silica · SEM/TEM-EDX analyses · Micro-CT analysis
M. Watanabe (*)
Department of Geography, Graduate School of Urban Environmental Sciences, Tokyo
Metropolitan University, Hachioji, Tokyo, Japan
e-mail: m.wata@tmu.ac.jp
A. Genseki
Materials Analysis Division, Open Facility Center, Tokyo Institute of Technology, Tokyo,
Japan
e-mail: genseki.aa@m.titech.ac.jp
© Springer Nature Singapore Pte Ltd. 2021
M. Watanabe (ed.), Sclerotia Grains in Soils, Progress in Soil Science,
https://doi.org/10.1007/978-981-33-4252-1_8
139
Micromorphological Features of Sclerotia
Grains
Makiko Watanabe and Akira Genseki
Abstract The micromorphological features of the interiors of sclerotia grains were
examined by scanning electron microscopy and transmission electron microscopy
combined with energy-dispersive X-ray (SEM-EDX, TEM-EDX) and micro computed tomography (micro-CT) analyses. Spherical particles with a diameter of
100 nm were found inside sclerotia grains and were found to be composed predominantly of carbon and aluminum, suggesting that they are melanin-like particles.
Spherical acicular structures, determined to be boehmite by TEM-EDX analysis,
were commonly observed by SEM in the center of sclerotia grains. In addition to
such aluminum polymorphs, aluminum sulfates and silicon spherical structures,
identified as opaline silica, were observed inside sclerotia grains. A graphene-like
fraction was observed in the center of sclerotia grains, near titanium oxides or small
amounts of adhering calcium, magnesium, or iron oxides. Micro-CT analysis of
intact sclerotia grains clearly showed the presence of mycelial strands, that were
confined to the interior of the grain.
Keywords Sclerotium grain · Melanin-like particles · Boehmite · Graphite · Opaline
silica · SEM/TEM-EDX analyses · Micro-CT analysis
M. Watanabe (*)
Department of Geography, Graduate School of Urban Environmental Sciences, Tokyo
Metropolitan University, Hachioji, Tokyo, Japan
e-mail: m.wata@tmu.ac.jp
A. Genseki
Materials Analysis Division, Open Facility Center, Tokyo Institute of Technology, Tokyo,
Japan
e-mail: genseki.aa@m.titech.ac.jp
© Springer Nature Singapore Pte Ltd. 2021
M. Watanabe (ed.), Sclerotia Grains in Soils, Progress in Soil Science,
https://doi.org/10.1007/978-981-33-4252-1_8
139