臺灣頭孢藻回顧及新紀錄由Cephaleuros parasiticus感染梨樹

A review of Cephaleuros in Taiwan, with description of C. parasiticus on Asian pear tree as a new record

本研究取得造成植物藻斑病的頭孢藻屬（Cephaleuros）絲狀藻類形態與分子特徵，近期在臺灣的亞洲梨（Pyrus pyrifolia）上採到的樣本鑑定為C. parasiticus。比較18S rDNA、ITS、rbcL條碼序列，梨上的頭孢藻序列與臨近愛玉上的頭孢藻樣本幾近相同，分析具良好親緣關係解析度的rbcL片段，所取得的序列與美國的C. parasiticus序列形成單系群。本研究首次在臺灣記錄C. parasiticus在P. pyrifolia上。回顧藻斑病在臺灣的文獻，島內的頭孢藻曾被發現在68個植物科內241種植物上，最常被記錄在樟科，其次分別是茶科、殼斗科植物上，頭孢藻的寄主大多數是森林樹木，而部分為經濟作物。雖然過去僅有C.virescens曾記錄在臺灣，本研究指出頭孢藻在此區域應有更高的多樣性。

Filamentous algae in the genus Cephaleuros that caused algal spot diseases were obtained for the morphological and molecular characterization. A recent collection on Asian pear tree (Pyrus pyrifolia) in Taiwan was identified as C. parasiticus. The 18S rDNA, ITS, and rbcL barcode sequences of the alga on P. pyrifolia were nearly identical to those on another host, Ficus pumila var. awkeotsang, found nearby. Using the rbcL DNA which showed great phylogenetic resolution, the sequences formed a monophyletic cluster with those of C. parasiticus from America. To our knowledge, this is the first record of C. parasiticus on P. pyrifolia in Taiwan. Reviewing the literature related to the algal leaf spot diseases in Taiwan, Cephaleuros has been reported on 241 plant species in 68 families in the island. They were most frequently found on the plant family Lauraceae, followed by Theaceae and Fagaceae. Most of the hosts were forest trees and some were economic crops. Although only C. virescens has been previously reported in Taiwan, this study suggests that Cephaleuros is more diversified in this region.