**Martina Kölle 1,\*, Rebecka Ringman <sup>2</sup> and Annica Pilgård 1,2**


Received: 25 November 2019; Accepted: 5 December 2019; Published: 7 December 2019

**Abstract:** Acetylation has been shown to delay fungal decay, but the underlying mechanisms are poorly understood. Brown-rot fungi, such as *Rhodonia placenta* (Fr.) *Niemelä*, *K.H. Larss.* & *Schigel*, degrade wood in two steps, i.e., oxidative depolymerization followed by secretion of hydrolytic enzymes. Since separating the two degradation steps has been proven challenging, a new sample design was applied to the task. The aim of this study was to compare the expression of 10 genes during the initial decay phase in wood and wood acetylated to three different weight percentage gains (WPG). The results showed that not all genes thought to play a role in initiating brown-rot decay are upregulated. Furthermore, the results indicate that *R. placenta* upregulates an increasing number of genes involved in the oxidative degradation phase with increasing WPG.

**Keywords:** brown-rot fungi; oxidative degradation; fenton degradation; acetylation; scots pine; *Pinus sylvestris*; *Postia placenta*
