167 Mycoscience 42:167-175, 2001 Taxonomy of Puccinia species causing rust diseases on sugarcane Eric V. Virtudazo 1}, Hidenobu Nojima 2) and Makoto Kakishima 1)~ 1) Institute of Agriculture and Forestry, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan 2) Kagoshima Agricultural Experiment Station, Kamifukumoto-cho, Kagoshima-shi, Kagoshima 891-0116, Japan Accepted for publication 25 December 2000 A taxonomic revision of Puccinia species causing rust diseases on sugarcane was conducted to clarify their morphologi- cal characteristics. Specimens including previously reported species, Puccinia melanocephala, P, kuehnii and Puccinia sp. sensu Muta, 1987, were collected in Japan and the Philippines and borrowed from various herbaria worldwide. Morphological characteristics of these specimens were examined under light and scanning electron microscopes. Comparative morphological studies of the specimens showed that rust fungi infecting sugarcane could be classified into two species, Puccinia melanocephala and P. kuehnii. Puccinia sp. sensu Muta was morphologically identical with P. kuehnii. Results of this study corroborate previous phylogenetic analysis results of D 1/D2 regions of LSU rDNA gene. Key Words Puccinia kuehnii; Puccinia melanocephala; sugarcane rusts; taxonomy; Uredinales. Puccinia melanocephala Syd. et P. Syd. and Puccinia miscanthi Miura or P. melanocephala. In 1986, Hennen kuehnii Butler are reported to cause rust diseases on found teliospores on specimens collected in Taiwan. sugarcane (Cummins and Hiratsuka, 1983; Hiratsuka and They were different from those described by Butler Kaneko, 1983; Sivanesan and Waller, 1986; Ryan and (1914) in color of telia and size of teliospores. How- Egan, 1989). These two species have been reported in ever, he reported them as mature teliospores of P. kueh- various parts of the world where sugarcane is cultivated. nfi and suggested that Butler (1914) observed immature In addition, Muta (1987) reported Puccinia sp. as an teliospores (Hennen, 1986). In 1987, Muta also found unidentified rust pathogen on sugarcane in the Nansei Is- teliospores similar to those described by Hennen (1986) lands, Kagoshima Pref., Japan. on sugarcane collected in the Nansei Islands and reported Puccinia kuehnii was first described as Urornyces them as Puccinia sp., because these specimens were kuehnii Krueger because of the presence of apically thick- different from P. kuehnii in the absence of paraphyses in walled urediniospores that were apparently mistaken as uredinia and telia. teliospores. It was later renamed as Uredo kuehnfi There was also confusion in the naming of P. (Kruegar) Wakker et Went, since the telial stage was not melanocephala, due to an apparent misidentification of found and the apically-thick walled spores were proven the host from which the original description was made. to be urediniospores (Sydow et al., 1906a; Ito, 1909; Bu- Sydow et al. (1906b) were the first to name it as P. tler, 1914;RyanandEgan, 1989). Butler (1914) found melanocephala on Bambusa sp., which was later found teliospores of this fungus on Saccharum spontaneurn L. to be Erianthus sp. (Cummins, 1971; Sathe, 1971). and named the species as Puccinia kuehnii. Most of sub- When Padwick and Khan (1944) found a rust on Erian- sequent descriptions of the telial stage of P. kuehniiwere thus rufipilis (Steud.) Griseb. (=E. fulvus Nees ex cited from his description because no teliospore was Stend.), they gave it a different name, P. erianthiPadwick found in either sugarcane or the other grass hosts (Laun- et Khan, which became the widely used name for the rust don and Waterson, 1964; Cummins, 1953, 1971; later found causing epidemics in commercial sugarcane. Sivanesan and Waller, 1986; Ryan and Egan, 1989). Al- When Cummins (1971) and Sathe (1971) found that the though the telial stage of P. kuehnii was reported by rust described by Sydow et al. (1906b) actually occurs Hiratsuka (1958), Teng and Ou (1937, cited by Tai, on an Erianthus sp., they proposed that it should be 1947), Tai (1947), Patel et al. (1950) and Chona and named P. melanocephala, since this name antedates the Munjal (1950), these descriptions were inconsistent with name P. erianthi, which becomes a nomenclatural dupli- those of Butler (1914) and similar to descriptions of P. cation. However, misidentification of P. rnelanocephala still occurs in more recent literature such as that of Pres- Contribution No. 157, Laboratory of Plant Parasitic Mycolo- ley et al. (1978) and other reports cited by Egan (1980). gy, Institute of Agriculture and Forestry, University of Tsuku- Egan (1980) showed that reports of P. kuehnii in Africa ba and the Americas were in fact P. me/anocephala based on ~ Corresponding author. E-mail: [email protected] previous records of sugarcane rusts and the non-suscep- 168 E.V. Virtudazo et al. tibility of the sugarcane varieties cultivated in these areas Results to P. kuehnii. Although recent reviews of rust diseases including Uredinia The lesions formed around the uredinia on the sugarcane rusts described the history, distribution, and specimens examined could be classified into two major characteristics of these rusts (Ryan and Egan, 1989; Pur- types. The first type is generally brown to dark brown, dy, 1985), there are still inconsistencies in descriptions with dark necrotic areas around uredinia, sometimes of certain morphological characteristics and variations coalescing to form large necrotic areas with many ure- among authors. In view of the lack of comprehensive dinia. The second type is generally lighter brown, some- taxonomic treatment of rust pathogens on sugarcane and times yellowish to yellow-orange, and with some brown the recent report of an unidentified rust from Japan, a necrotic areas around uredinia. taxonomic revision of these sugarcane rust pathogens However, the sugarcane rust specimens cannot be was considered necessary. readily distinguished based only on observations of the A previous study on the phylogenetic relationships of symptoms in old herbarium specimens, in specimens col- these sugarcane rusts revealed that sugarcane rusts can lected from the field, and in those produced from inocula- be clearly separated into two main phylogenetic groups tion experiments (data not shown). Most of the herbari- based on D1/D2 regions of LSU rDNA, although there um specimens labeled as P. melanocephala were found to was considerable divergence in the ITS regions (Virtuda- have the first type of lesion, while most of the herbarium zo et al., 2001). specimens labeled as P. kuehnii had the second type of This study was conducted to clarify the taxonomy of lesion. The lesions in most of the P. kuehnii specimens, the Puccinia species causing rust diseases on sugarcane which were mostly from very old collections, ranged and the taxonomic status of Puccinia sp. sensu Muta from pale yellow to yellow-orange. In certain speci- (1987) reported in the Nansei Islands, Kagoshima Pref., mens, reddish brown lesions were found and could not be Japan. distinguished from those found in most of the P. melanocephala specimens. Most of the specimens col- Materials and Methods lected from sugarcane fields in Japan and the Philippines had the second type of lesion, similar to those of speci- Collections were conducted in sugarcane fields and mens labeled as P. kuehnii: they were yellow or reddish agricultural experiment stations in Amamioshima Is., brown, and sometimes coalesced into large necrotic Kagoshima Pref. in June, 1996, in Okinawa Is., Miyako areas. The remaining specimens had the same type of Is., Ishigaki Is., and Iriomote Is., Okinawa Pref. in Decem- lesions as herbarium specimens of P. melanocephala. ber, 1996, and in the provinces of Negros Occidental and Uredinia observed in the specimens examined could Davao del Sur in the Philippines in August, 1996. These also be grouped into two types based mainly on color and collections were dried and kept at the Mycological Her- paraphyses. The first type generally were cinnamon- barium, Institute of Agriculture and Forestry, University brown to dark brown, mainly hypophyllous and linear, of Tsukuba (TSH). Dried herbarium specimens identified and with abundant paraphyses, which were sometimes as Puccinia melanocephala and P. kuehnii were borrowed more numerous than urediniospores in the uredinia (Fig. from the National Fungus Collections, United States 1B). The paraphyses were usually capitate, sometimes Department of Agriculture, Beltsville, USA (BPI), the spathulate, colorless to golden brown, with walls in the Arthur Herbarium, Purdue University, West Lafayette, head thicker than in the stipe (Fig. 1C). Uredinia found USA (PUn), the Herbarium of the Plant Disease Division, in most of the herbarium specimens of P. melanocephala Landcare Research, Auckland, New Zealand (PDD), the and some of the specimens collected in Japan and the Rijksherbarium, Leiden, Netherlands (L), Institute of Bota- Philippines were of this type. ny, Jagiellonian University, Krakow, Poland (KRAM), the The second type of uredinia ranged from orange to Mycological Herbarium, Swedish Museum of Natural yellowish brown, sometimes cinnamon-brown, and dis- History, Stockholm, Sweden (S), and from the collec- tinct paraphyses like those in the first type were absent. tions of the Shikoku Agricultural Experiment Station, Extremely thin-walled, sometimes obovoid or small, but Japan. Specimens examined are listed in the description more often irregularly shaped and hyaline para- of the species. physes-like