The Perigord black truffle responds to cold temperature with an extensive reprogramming of its transcriptional activity

Abstract

The Tuber melanosporum genome has been analysed with the aim of identifying and characterizing the genes involved in the environmental stress response. A whole genome array (7496 genes/probe) was used to verify the fungal transcriptional profiling upon a cold temperature period (7 days at 4 °C). A total of 423 genes resulted to be differentially expressed in a significant manner (>2.5-fold; p-value < 0.05) in the mycelia exposed to cold, compared to the control ones: 187 of these genes were up-regulated, while 236 were down-regulated. Sixty-six and fifty-one percent, respectively, of the up-or down-regulated transcripts had no KOG classification and were clustered as unclassified proteins, which was the most abundant category in the both up-and down-regulated genes. A gene subset, containing a range of biological functions, was chosen to validate the microarray experiment through quantitative real time PCR (qRT-PCR). The analysis confirmed the array data for 16 out of 22 of the considered genes, confirming that a cold temperature period influences the truffle global gene expression. The expressed genes, which mostly resulted to be genes for heat shock proteins (HSPs) and genes involved in cell wall and lipid metabolism, could be involved in mechanisms, which are responsible for fungal adaptation. Since truffle ascomata develop during the winter period, we hypothesize that these differentially expressed genes may help the truffle to adapt to low temperatures and/or perceive environmental signals that regulate the fructification.

Gene expression and metabolite changes during Tuber magnatum fruiting body storage

“…However, knowledge on the effect of these compounds on fungal differentiation is still limited (Brodhun and Feussner 2011). In the T. magnatum fruiting bodies studied in this investigation, extensive changes took place in the linoleate-derived metabolites during cold storage, a result that is in line with the induction of genes involved in the fatty acid metabolism observed by Zampieri et al (2011) in the mycelium of T. melanosporum during a cold treatment. In addition, O'Gorman et al (2012) have indicated pentadecanoic acid, linoleic acid, myo-inositol, benzoic acid and hexadecanoic acid as the five most important metabolites that could be used as markers for damage in A. bisporus.…”

“…Although it is not possible to be sure that the considered genes are homologous in the two fungi, this discrepancy could be due to the great difference in the considered storage temperature, i.e., 25 and 4 °C for Lentinula and Tuber, respectively. It has already been demonstrated that refrigeration (4 °C) has an effect on HSP gene expression in T. melanosporum mycelium, and a role of these proteins has been suggested during fungal adaptation to cold (Zampieri et al 2011). The regulation of TmaDHN1, which shows homology with T. borchii TbDHN1 and T. melanosporum TmelDHN1, which were previously observed to be differentially expressed during the reproductive stage as well as during the vegetative stage under stress conditions (Abbà et al 2006;Zampieri et al 2011), can be explained by the protective role of such a protein during cellular dehydration.…”

“…It has already been demonstrated that refrigeration (4 °C) has an effect on HSP gene expression in T. melanosporum mycelium, and a role of these proteins has been suggested during fungal adaptation to cold (Zampieri et al 2011). The regulation of TmaDHN1, which shows homology with T. borchii TbDHN1 and T. melanosporum TmelDHN1, which were previously observed to be differentially expressed during the reproductive stage as well as during the vegetative stage under stress conditions (Abbà et al 2006;Zampieri et al 2011), can be explained by the protective role of such a protein during cellular dehydration. Since tyrosinase and laccase activities have been shown to increase in L. edodes after harvest (Kanda et al 1996;Nagai et al 2003), T. magnatum sequences that code for a putative tyrosinase and laccase, which are involved in monophenols and polyphenols oxidation that can result in melanin synthesis, have been considered.…”

Gene expression in mycorrhizal orchid protocorms suggests a friendly plant–fungus relationship

“…RT-qPCR reactions were carried out in a StepOne apparatus (Applied Biosystem), following the protocol described in Zampieri et al (2011). The baseline range and CT values were automatically calculated using the StepOne software.…”

Genome-wide analysis of cell wall-related genes in Tuber melanosporum

“…Quantitative RT-PCR was carried out with StepOne apparatus (Applied Biosystem), according to the procedure described in Zampieri et al (2011). The baseline range and CT values were automatically calculated using the StepOne software.…”