(2845) Proposal to conserve the name Nicotiana benthamiana ( N. suaveolens var. cordifolia) (Solanaceae) with a conserved type

(2845) Nicotiana benthamiana Domin in Biblioth. Bot. 89: 591. Dec 1929 ≡ N. suaveolens var. cordifolia Benth., Fl. Austral. 4: 470. 16 Dec 1868, nom. cons. prop. Typus: Australia, Northern Territory, “The Granites, CA [Central Australia]”, Aug 1936, Cleland (AD No. 97219292!, right-hand plant; isotypi: AD Nos. 97219292!, left-hand plant, 95711022!, 95711023!, 97615135! & 97615134!, CANB No. 112241.1!, UC No. 188050 [photo!]), typ. cons. prop. Nicotiana benthamiana Domin (in Biblioth. Bot. 89: 591. 1929) has been previously treated as one of the more widely distributed of Australian species of Nicotiana sect. Suaveolentes (Solanaceae), distributed across the northern half of Australia. As part of studies on the section (e.g., Chase & al. in Ann. Bot. (Oxford) 92: 107. 2003) we have revealed that several morphologically distinctive, geographically structured forms or varieties of N. benthamiana across its range (Chase & Christenhusz in Bot. Mag. 35: 286–294. 2018) represent a species complex comprising five morphologically and genetically distinct species. An accession of one of these segregate species is a widely used model organism, especially in studies focusing on plant/virus interactions (Bally & al. in Annual Rev. Phytopathol. 56: 405–426. 2018). Its use in virus research is due to the ability of this strain, commonly referred to as LAB, to be infected with an immense range of plant viruses. LAB is also being used as a “biofactory” organism in the production of pharmaceuticals for both human and veterinary medicine, including the production of COVID-19 vaccines (Tregoning & al. in Clin. Exp. Immunol. 202: 162–192. 2020). This extensive use as a laboratory experimental organism results in Nicotiana benthamiana being cited 200 or more times per year for the last 20 years (Goodin & al. in Molec. Pl.-Microbe Interact. 21: 1015. 2008). A search in Google Scholar (on 7 July 2021) produced 56,700 articles in which the name N. benthamiana was used. The specific origin of LAB was unknown, but diligent research (Bally & al., l.c.) uncovered correspondence between J. Cleland (Waite Research Institute, University of Adelaide) and T.H. Goodspeed (Botanical Garden of the University of California) that demonstrated an accession collected by Cleland was sent to the Goodspeed laboratory in California in the 1930s, from where it made its way into research laboratories around the world. Cleland's collection came from a granite outcrop just south of The Granites gold mine site in the Tanami Desert, Northern Territory, and several vouchers were deposited at the AD, CANB, and UC herbaria. The LAB accession has been found to have a 72 base-pair insertion in its RNA-dependent RNA polymerase gene, Rdr1, that makes this non-functional, whereas in typical plants this gene confers resistance to many viruses. Most wild accessions of the Nicotiana benthamiana species complex that have been studied have an intact, functional copy of Rdr1 (Bally & al., l.c.). As we have been conducting our studies, we wished to understand more about the LAB accession and included it in our genetic studies. We have demonstrated that it is related to a set of accessions found in the Tanami/Timor Sea Coast topographic drainage (Australian Bureau of Meteorology, www.bom.gov.au/water), many of which also have this insertion in Rdr1. Nicotiana benthamiana was described by Domin (l.c.) as a replacement name for Nicotiana suaveolens var. cordifolia Benth. (Fl. Austral. 4: 470. 1868) in the description of which a single collection from the northwest coast of Australia (Bynoe s.n., now at K!) was cited. To preserve stability of the name N. benthamiana in the literature of plant pathology, virology and biotechnology, we propose the AD duplicate of the Cleland specimen sent to Goodspeed as the conserved type for N. benthamiana, ensuring that this widely used name is retained for the LAB accession that forms the basis for so much research. If the Bynoe s.n. collection is maintained as the type, it ties the name to a different member of the species complex, which will result in a new name for LAB. A new name for the LAB accession used in hundreds of laboratories in the plant/virus research community would cause confusion and potentially only be partially accepted, resulting in fragmentation of use and damage to not only the research in these laboratories but to the reputation of plant taxonomy. Conserving the name Nicotiana benthamiana with a conserved type as proposed would permit description of the four new species in this species complex without disturbing the use of N. benthamiana for LAB. Linking the name N. benthamiana to the original Cleland collection that was the source of the widespread LAB accession would ensure that its use in the plant virology and pathology literature will smoothly continue, regardless of results of future phylogenetic research. MWC, https://orcid.org/0000-0002-9927-4938 SK, https://orcid.org/0000-0001-7698-3945 LACS, https://orcid.org/0000-0003-1694-2433 MJMC, https://orcid.org/0000-0003-1398-8743