Phylogenetic study of two truffles, Tuber formosanum and Tuber furfuraceum, identified from Taiwan

Truffles are one of the most valuable edible fungi and have drawn extensive research interests worldwide. In Taiwan, two species of truffle, Tuber formosanum and Tuber furfuraceum, have been identified and reported. Although the morphological features of these two truffles have been described, lack of molecular identification has led to difficulties with firmly establishing their relatedness to other truffles. In this study, we utilized the internal transcribed spacer (ITS) and beta-tubulin gene sequences to generate the phylogenetic relationship of T. formosanum and T. furfuraceum with other taxonomic relatives. Our analysis revealed five/three major phylogenetic clades according to the 5.8S-ITS2/beta-tubulin gene sequences and corroborated with their morphological characterization. Tuber formosanum highly resembles the Tuber indicum B complex, while T. furfuraceum is most similar to Tuber huidongense. Based on a molecular clock, we estimated that T. furfuraceum and T. formosanum would have diverged from their close relatives in mainland China between 10.2 and 4.1 Ma, respectively. Based on the results, we propose that these two Tuber species found in Taiwan might originate from the common ancestors with some truffle species in China. However, due to a long divergence time and geographical separation, they have evolved into indigenous species of Taiwan.