Daldinia concentrica (Bolton) Ces. & De Not.

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Figure 1. The brown to black stroma on a downed ash trunk.

This fungus is a unique ascomycete, from its inconspicuous coal looking fruiting bodies. Yet these unassuming brown to black stroma are anything but unassuming. Instead they are a perennial structure that can grow up to 8 cm across (Figure 1). You will find these structures growing saprotrophically on dead or decomposing ash trees, which in Michigan we have a plethora of these days from emerald ash borer.

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Figure 2. The concentric rings from annual growth within the stroma.

 

Interestingly, when opening the stroma you will find concentric rings of annual growth. Each ring contains the former year’s perithecia that shot off ascospores (Figure 2). The next year a new layer of perithecia will develop along the outer edge of the stroma. When the ascospores are forcibly ejected, a black halo will develop on the surrounding wood (Figure 1). Spore prints of this fungus will reveal this halo effect up to 3 cm away from the stroma. The black ascospores are ellipsoidal to fusiform and average in size from 12-17 by 6-9 µm (Figure 3).

Daldinia concentrica is a part of the Ascomycetes within the class: Sordariomycetes, order: Xylariales and family: Xylariaceae. This fungus was first described in 1971 by James Bolton under the name Sphaeria concentrica. The fungus was transferred to the genus Daldinia in 1863 by Italian mycologists Ceasti and De Notaris.

Figure 3. The black ascospores from the outer layer of the stroma containing new perithecia.

Recently, the compound concentricolide was isolated from the fruiting bodies of the fungus. This compound was found to inhibit the cytopathoic effects of HIV. Which has since ben patented and synthesized for use as an anti-HIV agent.

 

Literature Cited:

Liu JK, Fang LZ 2009. First synthesis of racemic concentrocolide, an anti-HIV-1 agent isolated from the fungus Daldinia concentrica. Hertocycles DOI: 10.3987/COM-09-11704.

O’Reilly P 2011. Daldininia concentrica (Bolton) Ces. & De Not. –King Alfred’s cakes  in Fascinated by fungi http://www.first-nature.com/fungi/piptoporus-betulinus.php Access Nov 21, 2016.

Qin XD, Dong ZJ, Liu JK, Yang LM, Wang RR, Zheng YT, Lu Y, Wu YS, Zheng QT. 2006. Concentricolide, an anti-HIV agent from the ascomycete Daldinia concentrica. Helvetica chimica acta 89: 127-133.

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