Genome Designations in the Triticeae
Those attending the Second International Triticeae Consortium agreed to adopt a standard set of symbols for the individual haplomes of the Triticeae. A committee consisting of R.R.-C. Wang (Chair), R. von Bothmer, J. Dvorak, G. Fedak, I. Linde-Laursen, and M. Muramatsu met with two goals:
1) to develop a set of rules for designating haplome symbols for the Triticeae
2) to develop a set of symbols that based on existing knowledge of the tribe.
The results of their deliberations were published in the Proceedings of the Symposium. The information presented here is based on that publication and subsequent discussions.
I have taken the liberty of proposing an additional rule. It is clearly identified as such in what follows. To my mind, preparation and citation of voucher specimens is essential if the designation of haplome symbols and publication of haplomic constitutions are to have the permanence and verifiability that is critical to scientific work.
Anyone wishing to propose changes or additions to the rules and symbols presented here should contact Dr. R.R.-C. Wang. For errors in the Web pages, contact Dr. Mary Barkworth.
Rules for Haplome Designation
- Haplome symbols should be written in bold face.
- Different basic haplomes in the Triticeae (with x = 7), defined as having less than 50% of complete meiotic pairing (i.e., c < 0.5) in a a diploid hybrid in the absence of the Ph or other pairing promoter/suppressor gene effect, should be designated with different symbols.
- Single upper case letters of the Roman alphabet (A-Z) should, as far as possible, be used as symbols for the basic haplomes.
- Additional basic haplomes should be designated by an upper case letter followed by a lower case letter.
- The haplome designation of a polyploid taxon should be given as a combination of the symbols of its constituent basic diploid haplomes.
- Unknown or unverified haplomes should be designated X followed by a lower case letter (e.g., Xu for Hordeum murinum). When a haplome has been sufficiently identified as distinct from all other established basic haplomes, it should be given its own haplome symbol.
- The letter Y has previously been used to designate unknown haplomes, but it has also been extensively used to designate on the haplomes present in species of Elymus sensu lato. It is now restricted to use in Elymus sensu lato.
- Modified versions of a basic haplome should be indicated by superscripts in lower case that are indicative of one of the species carrying such modified haplomes. Further modifications may be indicated by superscripted numerals.
- When a previously unrecognized basic haplome is identified, a symbol should be assigned to it in accordance with these rules.
- A haplome symbol may be underlined to indicate the origin of the cytoplasm of an alloploid species.
- From 1996 on, the haplome symbols designations presented here should have priority over subsequent proposals.
Proposed Addition to the Rules (no action has been taken on this proposal).
Any time the haplomic constitution of a taxon is determined, a herbarium specimen shall be prepared from a mature plant of the material used. This voucher specimen must be deposited in an internationally recognized herbarium. Publication of the haplomic constitution must include the code of this herbarium and sufficient additional information to enable the specimen concerned to be identified unequivocally.
Comment: Correct identification of the material used is essential if determinations of haplomic constitution are to be of value. Deposition of voucher material ensures that determinations can be verified at a later date and that, if the taxonomy of the group involved is changed, the haplomic information can be associated with the appropriate newly recognized or modified taxa.
A useful criterion for "internationally recognized herbarium" is listing in Index Herbariorum but the most critical aspect is that it should be a herbarium whose specimens are regularly consulted by taxonomists and one that is willing to loan specimens to other herbaria on request. Personal herbaria do not meet these criteria, nor do some research station herbaria.
The table below is based on Wang et al. (1996), but I have a) changed the generic concepts adopted, b) listed the taxa alphabetically, c) eliminated the references to previous designations, and e) added a column for listing the accession code and number of herbarium specimens that document a particular report. The reason for adding the last column is given above.
I have also started a set of files for listing all taxa in the Triticeae in which the haplomic constitution of each taxon will be listed, if it has been determined directly rather than inferred from its morphology. This set of files will be built up slowly, as time permits.
|Taxon||Haplomic Symbol or Constitution||Reference||Voucher Specimen|
|Aegilops crassa (4x)||DcXc||Zhang et Dvorak 1992|
|Aegilops crassa (6x)||DDcXc||Zhang et Dvorak 1992|
|Aegilops juvenalis||DcZcU||McNeil et al. 1994|
|Aegilops mutica||T||Kimber et Tsunewaki 1988;|
|Aegilops recta||UMN, UMX||Kimber et Tsunewaki 1988;; Yen et Kimber 1992|
|Aegilops speltoides||S. Proposal to change to B||Jauhar et al. 1999. Journal of heredity 90:437-445.|
|Aegilops triuncialis||UC||Kimber et Tsunewaki 1988;|
|Kimber et Tsunewaki 1988; Zhang et al. 1992|
|Aegilops ventricosa||DN||Kimber et Tsunewaki 1988|
|Dasypyrum breviaristatum||Vb||Shoji Ohta & Miki Morishita (in press)|
|Elymus batalinii||StPY||Jensen 1990|
|Elymus caucasicus||StY||Jensen et Wang 1991|
|Elymus drobovii||StHY||Dewey 1980|
|Elymus repens (Type species of Elytrigia)||StStH||Assadi et Runemark 1994; Vershinin et al. 1994|
|Elymus scabrus||StWY||Torabinejad et Mueller 1993|
|Elymus sibiricus (Type species of Elymus)||StH|
|Elymus transhyrcanus||StStH||Dewey 1972|
|Eremopyrum||FXe||Sakamoto 1979; Frederiksen et Bothmer 1989|
|Hordelymus||XoXr||Bothmer et al. 1994|
|Hordeum marinum||Xa||Bothmer et al. 1986|
|Hordeum murinum||Xu||Bothmer et al. 1987, 1988a, 1998b|
|Hordeum, other species||H|
|Kengyilia||StPY||Yen et Yang 1990|
|Leymus||NsXm||Zhang et Dvorak 1991; Wang et Jensen 1994|
|Pascopyrum smithii||StHNsXm||Zhang et Dvorak 1991|
|Peridictyon sanctus||Xp||Seberg et al. 1991|
|Pseudoroegneria deweyi||StP||Jensen et al. 1992|
|Pseudoroegneria geniculata subsp. scythica||EeSt||Liu et Wang 1992|
|Pseudoroegneria pertenuis||StP||Wang et al. 1986; Assadi 1995|
|Thinopyrum bessarabicum||Eb||Wang 1985|
|Thinopyrum caespitosum||EeSt||Liu et Wang 1989, 1993b|
|Thinopyrum curvifolium||Eb Eb||Liu et Wang 1993a|
|Thinopyrum distichum||EbEe||Liu et Wang 1993a|
|Thinopyrum elongatum||Ee||Wang 1985|
|Liu et Wang 1993b
Xu et Conner 1994
|Thinopyrum junceiforme||EbE e||Liu et Wang 1992|
|Thinopyrum junceum||EbEbEe||Liu et Wang 1993a|
|Thinopyrum nodosum||EeSt||Liu et Wang 1993b|
|Thinopyrum sartorii||EbE e||Liu et Wang 1992|
|Thinopyrum scirpeum||EeEe||Liu et Wang 1993a|
|Triticum durum||AuB||Dvorak et al. 1993|
|Triticum monococcum||Am||Dvorak et al. 1993|
|Kimber et Tsunewaki 1988; Yen et Kimber 1992|
|Kimber et Tsunewaki 1988; Zhang et Dvorak 1992|
|Triticum timopheevii||AuG||Dvorak et al. 1993|
|Triticum zhukovskyi||AmAuG||Dvorak et al. 1993|
|Triticum uartu||Au||Dvorak et al. 1993|