Phylogeny, taxonomy and chemical analysis of amanita in northern and northeastern thailand

Abstract

Amanita is an emblematic genus and the focal point of various research programs. Up to now, about 700 species have been reported worldwide. Most Amanita species form ectomycorrhizal symbiosis with plants, which is important to the local forest ecosystem. In addition, Amanita contains both well-known edible and fearsomely deadly species, which continuously affect local people’s life either by offering tasty nutrients or causing poisonous cases. On one hand, despite being located in a tropical region, and possessing a seasonal climate and complex topography, the species diversity of Amanita in Thailand is limited. On another hand, there is a significant gap between Thailand and other countries in the field of nutrient analysis of edible Amanita and toxin analysis of poisonous Amanita. Based on the aforementioned reasons, this study carried out the relevant research, which aims to provide a considerable contribution to the Thai Amanita research. During the rainy seasons from 2018 to 2020, a total of 350 specimens were collected from 14 provinces in northern Thailand (Chiang Mai, Chiang Rai, Lampang, Lamphun, Nan, Phayao, Phetchabun, and Phitsanulok) and northeastern Thailand (Kalasin, Khon Kaen, Loei, Mukdahan, Nong Bua Lam Phu, and Sakon Nakhon). By utilizing both the morphological characteristics and multi-gene phylogenetic (nrLSU, ITS, RPB2, TEF1-α, and TUB) analyses, we accurately recognized 23 species. All these 23 species belong to three subgenera and seven sections, viz. sections Amanita (seven species), Caesareae (four species), Amidella (two species), Phalloideae (one species), Roanokenses (four species), Validae (two species), and Lepidedlla (three species). Among these taxa, seven are reported as new to science, and eight are reported as new to Thailand. Seven new taxa described are as follows: A. kalasinensis, A. ravicrocina, and A. submelleialba from the sect. Amanita; A. claristriata and A. fulvisquamea from the sect. Amidella; A. albifragilis from the sect. Phalloideae; and A. albicarnosa from the sect. Lepidella. Eight new records to Thailand identified are as follows: A. elata from the sect. Amanita; A. pseudoprinceps and A. subhemibapha from the sect. Caesareae; A. griseofarinosa and A. neoovoidea from the sect. Roanokenses; A. citrinoannulata and A. cacaina from the sect. Valid; and A. aureofloccosa from the sect. Lepidella. By utilizing both the morphological characteristics and multi-gene phylogenetic analyses, 19 specimens collected from nature or bought from local markets were identified as four Amanita species, viz. A. hemibapha, A. pseudoprinceps, A. rubromarginata, and A. subhemibapha. Six samples representing these four Amanita species were selected to carry out nutritional composition, total phenolic content, antioxidant, and α-glucosidase inhibitory activities. The results indicate that A. pseudoprinceps and A. subhemibapha contain significantly higher protein contents than A. hemibapha and A. rubromarginata. Amanita pseudoprinceps showed the highest content of fiber. Amanita rubromarginata had the highest ash content. In addition, A. hemibapha contained significantly higher carbohydrate content than the other Amanita species, and A. rubromarginata contained the highest fat content. Amanita pseudoprinceps contained the highest value of total phenolic content, DPPH activity, and α-glucosidase inhibition activity over the other three species. Twenty-three samples representing 23 taxa were selected, and carried out the toxicity determinations. Five deadly toxins, viz. α-amanitin, β-amanitin, γ-amanitin, phallacidin, and phalloidin were set as standard to test the content of these toxins in selected Amanita species. The high-performance liquid chromatography (HPLC) was adopted to separate and detect the five deadly toxins in selected Amanita species. The results showed that A. albifragilis belonging to Amanita sect. Phalloideae contains both α-amanitin (522.8 μg/g) and β-amanitin (1,473.3 μg/g) toxins. Conversely, the other 22 samples representing 22 taxa didn’t contain any of these five toxins.