Goplana dioscoreae

Goplana dioscoreae (winged yam rust) is a rust fungus reported from Asia and Pacific Islands and, as the synonym Uredo dioscoreae-alatae, is listed as of quarantine significance for the United States.

Winged yam (Dioscorea alata L.) is originally from continental tropical Asia and produces large, edible tubers, and is an important source of the steroid diogenin used in birth control pills. Dioscorea alata was introduced into the Americas and is considered an invasive vine in Florida where it can produce stems up to 30 ft. long.

Goplana dioscoreae Cummins

Spermogonia, aecia unknown.

Uredinia amphigenous, on petioles, and caulicolous, deep-seated in host tissues, long covered by elevated, cupulate, thick, dark brown host tissue, erumpent by irregular central apertures, small, less than 1 mm diam, scattered or grouped in areas up to ½ cm diam, on dark leaf spots. Urediniospores pedicellate, sub-globose to ellipsoid, almost hyaline to pale yellow to pale chestnut-brown, 17-28 ×14-22 µm, wall echinulate, 2-3 µm thick; pores 6-9, scattered, obscure.

Telia hypophyllous, minute, densely gregarious, subepidermal, erumpent, waxy and gelatinous when wet. Teliospores in groups, on large, laterally free cells, cylindric, (46-) 50-77 × 7-11 µm, walls thin, colorless; metabasidia form by continuous apical elongation of probasidial cells.

Hosts: Dioscorea alata L., Dioscorea bulbifera L., Dioscorea esculenta (Lour.) Burkill, Dioscorea transversa R. Br., and Dioscorea sp. (Dioscareaceae).

Geographic distribution: Australia, Brunei, Indonesia, Java, Malaysia, New Caledonia, Pacific Islands, Papua New Guinea, Philippines, Singapore, Sri Lanka.

Several rust fungi are reported on species of Dioscorea. At present, only seven rust taxa are known to occur in the western hemisphere: Aecidium dioscoreae J.C. Linq., Cerotelium dioscoreae Berndt, Goplana ecuatoriana Syd., Puccinia valida Arthur, Sphenospora pallida (G. Winter) Dietel, U. dioscoreicola Kern, Cif. & Thurst., and Uredo pallatangae Jorst. No rust on species of Dioscorea was reported from Europe, but a number of rust fungi were reported from Africa, Asia an Oceania.

Two species of Aecidium are reported on species of Dioscorea: Aecidium dioscoreae J.C. Lindq. and Aecidium leonense Cummins have an Aecidium-type anamorph with peridial cells, differing from the anamorph of G. dioscoreae, which has Uredo-type without peridial cells.

Cerotelium dioscoreae Berndt has urediniospores with two equatorial germ pores while urediniospores of G. dioscoreae have 6-9 obscure scattered germ pores.

Two other species of Goplana are reported on species of Dioscorea: G. australis Ono and J.F. Hennen produces urediniospores with (4-) 6-8 (9) equatorial germ pores, while urediniospores of G. dioscoreae have obscure, scattered (6-9) germ pores. G. ecuatoriana Syd. has paraphysate uredinia while uredinia of G. dioscoreae are aparaphysate.

One species of Phakopsora is reported on species of Disocorea: P. dioscoreae Thaung with peripheral paraphysate uredinia, while uredinia of G. dioscoreae have no paraphyses.

Two species of Puccinia are reported on species of Dioscorea: P. dioscoreae Kom. and P. valida Arthur produce teliospores that are one-septate and urediniospores with two germ pores, while teliospores of G. dioscoreae are non-septate and urediniospores have 6-9 obscure scattered germ pores.

One species of Sphenospora, S. pallida (G. Winter) Dietel, is reported on several species of Dioscorea from Belize, Brazil, Costa Rica, Ecuador, Guatemala, Panama, Peru, and Venezuela. The reports are mostly of the uredinial stage with urediniospores (20-) 22-26 (-29) × 19-22 µm while urediniospores of G. dioscoreae are smaller, 17-28 x 14-22 µm.

Seven species of Uredo have been reported on species of Dioscorea: Uredo dioscoreae-aculaetae Racib. has urediniospores that are bilaterally ovate, spiny on convex surface and smooth on the lower surface (Hemileia-like) while urediniospores of G. dioscoreae are evenly echinulate. U. dioscoreae-filiformis Racib. has obovoid, ellipsoid or pyriform urediniospores measuring 28-38 × 20-26 µm, U. dioscoreae-sativae Syd. & P. Syd. has obovoid, ellipsoid, pyriform to oblong, often angular urediniospores measuring (19-) 21-35 (-37) × 14-22 (-23) µm, and U. pallatangae Jorst. has urediniospores oblong, ellipsoid to obovoid 32-45 × 14-28 µm, while urediniospores of G. dioscoreae are sub-globose to ellipsoid and measuring 17-28 × 14-22 µm. Urediniospores of U. dioscoreicola Kern, Cif. & Thurst. have 3-4 equatorial germ pores and Uredo xenoporula P. Syd. & Syd. has urediniospores with a single germ pore at the base of the spore next to the pedicel while urediniospores of G. dioscoreae have obscure scattered (6-9) germ pores. U. spinulosa Ono has abundant uredinial paraphyses, while uredinia of G. dioscoreae are aparaphysate.

References:

Cummins, G.B. 1941. Uredinales of New Guinea -- III. Mycologia 33: 143-154.

Ono, Y. 1982. Rusts of yams in Southeast Asia and South Pacific. Trans. Brit. Mycol. Soc. 79: 423-429.

Ono, Y., and Hennen, J.F. 1983. Taxonomy of the Chaconiaceous genera (Uredinales). Trans. Mycol. Soc. Japan 24: 369-402.

Raciborski, M. 1900. Parasitische Algen und Pilze Java's I. Theil. Staatsdruckerei, 39 pages.

Nomenclature

Specimens in BPI

Additional distribution data

Suggested citation: Hernández, J.R. Systematic Mycology and Microbiology Laboratory, ARS, USDA. 6 January 2006. Invasive Fungi. Goplana dioscoreae. Retrieved November 21, 2009, from http://nt.ars-grin.gov/sbmlweb/fungi/index.cfm .