Preserving the Biologically Coherent Generic Concept of Phytophthora, 'Plant Destroyer'

  • Published:
  • Authors: Brasier CM, Grünwald NJ, Bourret TB, Govers F, Scanu B, Cooke DEL, Bose T, Hawksworth DL, Abad ZG, Albarracin MV, Alsultan W, Altamirano-Junqueira AE, Arifin AR, Arnet MJ, Aumentado HDR, Bakonyi J, Belisle WH, Benigno A, Bienapfl JC, Bilodeau GJ, Blair JE, Botella L, Brandano A, Cacciola SO, Carbone I, Castroagudin VL, Chaendaekattu N, Consford JD, Corcobado T, Covey PA, Daniels HA, Deidda A, Dorrance AE, Dort EN, Drenth A, Drizou F, Evangelisti E, Fajardo SN, Fang Y, Ference CM, Frankel SJ, Goss EM, Guest DI, Hardy GESJ, Harris ARH, Hawku MD, Heungens K, Hong C, Horner IJ, Horta Jung M, Iyanda OJ, Jamieson BA, Jeffers SN, Judelson HS, Junaid M, Kalogeropoulou E, Kamoun S, Kang S, Kasuga T, Kudláček T, LeBoldus J, Lee CA, Li D, Llanos AK, Lopez-Nicora HD, Machado H, Maia C, Mandal K, Manosalva P, Martin FN, Matson MEH, McDougal RL, McDowell JM, Michelmore RW, Milenković I, Moricca S, Mostowfizadeh-Ghalamfarsa R, Nagy ZÁ, Nikolaeva EV, Ortega-López P, Paap T, Parada-Rojas CH, Peduto Hand F, Perez-Sierra A, Pettersson M, Prasad P, Puig AS, Raco M, Rajput NA, Ristaino JB, Rooney-Latham S, Seidl MF, Shamoun SF, Solla A, Spies CFJ, Sudermann MA, Swiecki TJ, Tian M, Tripathy S, Uematsu S, Van Poucke K, Vichou AE, Walter M, Webber JF, Williams NM, Wingfield MJ, Yadav D, Yang X, Jung T (2025)
  • Reference: Phytopathology 2025 Mar 12. doi: 10.1094/PHYTO-11-24-0372-LE

Phytophthora is a long-established, well known and globally important genus of plant pathogens. Phylogenetic evidence has shown that the biologically distinct, obligate biotrophic downy mildews evolved from Phytophthora at least twice. Since, cladistically, this renders Phytophthora'paraphyletic', it has been proposed that Phytophthora evolutionary clades be split into multiple genera (Runge et al. 2011; Crous et al. 2021; Thines et al. 2023; Thines 2024). In this letter, we review arguments for the retention of the generic name Phytophthora with a broad circumscription made by Brasier et al. (2022) and by many delegates at an open workshop organized by the American Phytopathological Society. We present our well-considered responses to this proposal in general terms and to the specific proposals for new genera; together with new information regarding the biological properties and mode of origin of the Phytophthora clades. We consider that the proposals for new genera are mostly non-rigorous and not supported by the scientific evidence. Further, given (1) the apparent lack of any distinguishing biological characteristics (synapomorphies) between the Phytophthora clades; (2) the fundamental monophyly of Phytophthora in the original Haeckelian sense; (3) the fact that paraphyly is not a justification for taxonomic splitting; and (4) the considerable likely damage to effective scientific communication and disease management from an unnecessary break-up of the genus, we report that Workshop delegates voted unanimously in favour of preserving the current generic concept and for seeking endorsement of this view by a working group of the International Commission on the Taxonomy of Fungi.