Suggested guidelines for the nomenclature and abbreviation of the genetic stocks of wheat and its relatives

W. J. Raupp, B. Friebe, and B. S. Gill

Department of Plant Pathology, Throckmorton Hall, Kansas State University, Manhattan, KS 66506-5502, USA. This is contribution 95-541-J from the Kansas Agricultural Experiment Station, Manhattan.

The current nomenclature for describing the aneuploids of common wheat was introduced by Sears in 1954 and described in detail by Kimber and Sears in 1968. This nomenclature can be lengthy, and its use in manuscripts and descriptive figures cumbersome. Additionally, the needs of computerized databases require a shortening of these terms to save time and storage space. The ability to search lists of stocks suggests the need for succint, descriptive abbreviations for the genetic stocks in wheat. GrainGenes, the wheat genome database, is no exception as search criteria can yield several screens of data. The purpose of this communication is to provide a list of recommended abbreviations for the aneuploid lines and genetic stocks in wheat.

Several recommended guidelines presented by Kimber and Sears (1968) will be used. These include designating:

  1. telocentric chromosomes with the letter "t",

  2. isochromosomes with the letter "i",

  3. the ability of chromosomes to pair with superscripts following the chromosome symbols. The actual pairing may vary considerably from cell to cell. The idealized pairing configuration is indicated in all cases even though it may rarely form,

  4. chromosome status shown by the chromosome number followed by symbols indicating the configuration,

  5. chromosome arms by S (genetically short) or L (genetically long), and

  6. substituted chromosomes by the homoeologous group number and genome designation. The designation of the chromosome that was replaced follows in parentheses.

Publications by Gill (1986) and Gill et al. (1991) added additional descriptors for wheat genetic stocks. The symbols were based on suggestions by the Chicago (1966) and Paris Conferences (1971) for Standardization in Human Cytogenetics. Where applicable, these conventions will also be used:

  1. single and three letter designations specify rearranged chromosomes, such as "del" for deletion and "r" for ring chromosome,

  2. the short system for defining translocation lines includes only the break points and the following punctuation: " · " indicates a break at the centromere, a dash, " - ", indicates an interstitial breakpoint, and a slash " / " indicates an unknown breakpoint,

  3. the detailed system describes translocation lines by defining their band composition and the additional symbols, " : " break (terminal deletion), " :: " break and join, and

  4. a translocation chromosome is indicated by a "T" preceding a description of the translocation. Further descriptions of translocated chromosomes are given in Gill et al. (1991) and will be described as needed.

A brief survey of the literature published in the proceedings of the International Wheat Genetics Symposia (I through VII), as well as later issues of the journal GENOME, indicate that the choice of terminology is left to the authors. However, it seems that over time, some conventions were standardized. These are the designation of:

  1. nullisomic lines with an "N" followed by the designated chromosome and genome,

  2. monosomic lines with an "M" followed by the designated chromosome and genome,

  3. the disomic condition with a "D" followed by the designated chromosome and genome,

  4. the trisomic condition with "Tri" followed by the designated chromosome and genome,

  5. tetrasomic lines with a "T" followed by the designated chromosome and genome. A "T" is also the designator for translocation lines to be consistent with current literature,

  6. nullisomic-tetrasomic lines with an "N" followed by the number and genome of the nullisomic chromosome and a "T" followed by the same for the tetrasomic chromosome, as in N1A T1B,

  7. monosomic and disomic additions by "MA" and "DA", respectively, and

  8. monosomic and disomic substitutions as "MS" and "DS", respectively, followed by chromosome designation as indicated in rule vi, and

  9. abbreviations for wheat cultivars according to "Wheat Cultivar Abbreviations", 1985, Special Report 749, Agricultural Experiment Station, Oregon State University, Corvallis. This publication is currently under revision by CIMMYT.

Rules of hierarchy, established to ensure consistency in the naming of stocks, include that:

  1. the short arm is listed before the long arm,

  2. the monosomic condition (either for the whole chromosome, chromosome arms, or parts thereof) is listed before the disomic condition except in cases where it is superceeded by rule xxii,

  3. telosomic chromosomes are listed before isosomic chromosomes,

  4. in translocation chromosomes, the common wheat chromosome regardless of arm, is listed before the alien chromosome segment, and

  5. in translocation chromosomes between two alien chromosomes where the breakpoint is unknown, the order is according to homoeologous group.

Some stocks require abbreviations or symbols that were previously neither required nor based on the guidelines presented here. These include:

  1. "Mt" and "Dt" indicate monotelo- and ditelosomic lines following rules i (for telochromosomes), xii, and xiii,

  2. the doubled condition is indicated with a "d" followed by the designated chromosome and genome, and

  3. the number sign " # " is used to distinguish different chromosomes belonging to the same homoeologous group of chromosomes within accessions, between accessions of the same nondomesticated species, or between homologous chromosomes within a cultivar.

Finally, certain symbols for use in computer databases, where some text styles are not available, include that:

  1. the symbol " ^ " encloses characters to be superscripted, and

  2. the symbol " ` " encloses characters to be subscripted.

The following is a list of each aneuploid type or genetic stock, with an example of how the data would be displayed in each of the GrainGenes model fields for germplasm. For simplicity, chromosome 1A of wheat is used along with a homoeologue in rye (Secale cereale) or Triticum longissimum where needed. All of the chromosome stocks are represented to appear in the cultivar "Chinese Spring", hereafter designated by the abbreviation CS. The first column lists the variable name from the GrainGenes germplasm model (see Appendix I for a list of all variables available in this model). The second column lists the actual data that will appear in the database next to the variable name. Chromosome configuration is included with respect to item iii above. Finally, a comment is included where required.

NULLISOMIC                 N
Germplasm                  Chinese Spring Nullisomic 1A
Abbreviation               CS N1A
Species                    Triticum aestivum
Type                       Aneuploid
Derived_from               Chinese Spring
Chromosome_configuration   20"+0'1A
Chromosome_number          40

MONOSOMIC                  M
Germplasm                  Chinese Spring Monosomic 1A
Abbreviation               CS M1A
Species                    Triticum aestivum
Type                       Aneuploid
Derived_from               Chinese Spring
Chromosome_configuration   20"+1'1A
Chromosome_number          41

TRISOMIC                   Tri
Germplasm                  Chinese Spring Trisomic 1A
Abbreviation               CS Tri1A
Species                    Triticum aestivum
Type                       Aneuploid
Derived_from               Chinese Spring
Chromosome_configuration   20"+1"'1A
Chromosome_number          43
Comment                    The abbreviation "Tri" was selected 
                           because the letter " T " already 
                           indicates tetrasomy and translocation
                           lines. The other choice "Tr" might 
                           cause confusion with translocation 
                           line nomenclature.

TETRASOMIC                 T 
Germplasm                  Chinese Spring Tetrasomic 1A
Abbreviation               CS T1A
Species                    Triticum aestivum
Type                       Aneuploid
Derived_from               Chinese Spring
Chromosome_configuration   20"+1""1A
Chromosome_number          44

NULLISOMIC-TETRASOMIC      N T
Germplasm                  Chinese Spring Nullisomic 1B-Tetrasomic 1A
Abbreviation               CS N1B-T1A
Species                    Triticum aestivum
Type                       Aneuploid
Derived_from               Chinese Spring
Chromosome_configuration   19"+1""1A(1B)
Chromosome_number          42
Comment                    Using rule vi, this could be 
                           abbreviated "CS NT1B(1A)", but 
                           we believe the above to be more 
                           easily read. 

MONOTELOSOMIC              Mt
Germplasm                  Chinese Spring Monotelosomic 1AS
Abbreviation               CS  Mt1AS
Species                    Triticum aestivum
Type                       Aneuploid
Derived_from               Chinese Spring
Chromosome_configuration   20"+t'1AS
Chromosome_number          41t

DITELOSOMIC                Dt 
Germplasm                  Chinese Spring Ditelosomic 1AS
Abbreviation               CS Dt1AS
Species                    Triticum aestivum
Type                       Aneuploid
Derived_from               Chinese Spring
Chromosome_configuration   20"+t"1AS
Chromosome_number          42tt

DOUBLE MONOTELOSOMIC       dMt
Germplasm                  Chinese Spring Double Monotelosomic 1A
Abbreviation               CS Mt1AS-Mt1AL
Species                    Triticum aestivum
Type                       Aneuploid
Derived_from               Chinese Spring
Chromosome_configuration   20"+t'1AS+t'1AL
Chromosome_number          42t+t
Comment                    The use of a "+" in the 
                           chromosome_number field will 
                           distinguish this line from 
                           ditelosomic lines since both lines 
                           have two telochromosomes.

DOUBLE DITELOSOMIC         dDt
Germplasm                  Chinese Spring Double Ditelosomic 1A
Abbreviation               CS dDt1A
Species                    Triticum aestivum
Type                       Aneuploid
Derived_from               Chinese Spring
Chromosome_configuration   20"+t"1AS+t"1AL
Chromosome_number          44tt+tt

DITELO-MONOTELOSOMIC       Dt Mt
Germplasm                  Chinese Spring Ditelosomic 
                           1AS-Monotelosomic 1AL
Abbreviation               CS Dt1AS-Mt1AL
Species                    Triticum aestivum
Type                       Aneuploid
Derived_from               Chinese Spring
Chromosome_configuration   20"+t"1AS+t'1AL
Chromosome_number          43tt+t
Comment                    The ditelosomic chromosome is 
                           listed first regardless of arm, thus 
                           the abbreviation for the line 
                           ditelosomic 1AL-monotelosomic 
                           1AS lists the long arm first.

MONO-ISOSOMIC              Mi
Germplasm                  Chinese Spring Mono-isosomic  1AS
Abbreviation               CS Mi1AS
Species                    Triticum aestivum
Type                       Aneuploid
Derived_from               Chinese Spring
Chromosome_configuration   20"+i'1AS
Chromosome_number          41i

DI-ISOSOMIC                Di 
Germplasm                  Chinese Spring Di-isosomic 1AS
Abbreviation               CS Di1AS
Species                    Triticum aestivum
Type                       Aneuploid
Derived_from               Chinese Spring
Chromosome_configuration   20"+i"1AS
Chromosome_number          42ii

MONOSOMIC ADDITION         MA 
Germplasm                  Chinese Spring-Imperial Monosomic Addition 1R
Abbreviation               CS-I MA1R
Species                    Triticum aestivum
Donor_species              Secale cereale cv. Imperial
Type                       Aneuploid
Derived_from               Chinese Spring
Chromosome_configuration   21"+1'1R
Chromosome_number          43
Comment                    Where duplicate lines from the same 
                           cultivar are available, it may be 
                           necessary to add a number or 
                           symbol to distinguish them.

DISOMIC ADDITION           DA
Germplasm                  Chinese Spring-Imperial Disomic Addition 1R
Abbreviation               CS-I DA1R
Species                    Triticum aestivum
Donor_species              Secale cereale cv. Imperial
Type                       Aneuploid
Derived_from               Chinese Spring
Chromosome_configuration   21"+1"1R
Chromosome_number          44
Germplasm                  Chinese Spring-T. longissimum 
                           Disomic Addition 1S^l^
Abbreviation               CS-TLON DA1S^l^
Species                    Triticum aestivum
Donor_species              T. longissimum
Donor_ID                   Texas A&M, accession #2
Type                       Aneuploid
Derived_from               Chinese Spring
Chromosome_configuration   21"+1"1S^l^
Chromosome_number          44
Developed_by               N. A. Tuleen
Development_site           Texas A&M University, College Station
Comment                    The genome for T. longissimum is 
                           S superscript " l ".

MONOSOMIC 
SUBSTITUTION               MS
Germplasm                  Chinese Spring-Imperial 
                           Monosomic Substitution 1R(1A)
Abbreviation               CS-I MS1R(1A)
Species                    Triticum aestivum
Donor_species              Secale cereale cv. Imperial
Type                       Substitution
Derived_from               Chinese Spring
Chromosome_configuration   20"+1'1R(1A)
Chromosome_number          41

DISOMIC SUBSTITUTION       DS 
Germplasm                  Chinese Spring-Imperial Disomic 
                           Substitution 1R(1A)
Abbreviation               CS-I DS1R(1A)
Species                    Triticum aestivum
Donor_species              Secale cereale cv. Imperial
Type                       Substitution
Derived_from               Chinese Spring
Chromosome_configuration   20"+1"1R(1A)
Chromosome_number          42

INTERVARIETAL DISOMIC
SUBSTITUTION               DS 
Germplasm                  Chinese Spring-Wichita Disomic 
                           Substitution 1A WI(1A CS)
Abbreviation               CS-WI DS1A
Species                    Triticum aestivum
Type                       Substitution
Donor_species              Wichita
Derived_from               Chinese Spring
Chromosome_configuration   20"+1"1A WI(1A CS)
Chromosome_number          42
Comment                    The substituting chromosome is part 
                           of the name, the substituting 
                           chromosome named in parentheses.  
                           For abbreviations, when cultivars 
                           substitute same chromosome, it 
                           need only be listed once. 

TRANSLOCATION 
CHROMOSOMES                T 

TERMINAL TRANSLOCATION WITH CENTROMERIC BREAKPOINT
Germplasm                  Chinese Spring-Imperial 
                           Translocation T1AS·1RL
Abbreviation               CS-I T1AS·1RL
Species                    Triticum aestivum
Donor_species              Secale cereale cv. Imperial
Type                       Translocation
Translocation_description  Terminal translocation with
                           centromeric breakpoint
Derived_from               Chinese Spring
Chromosome_configuration   20"+1"T1AS·1RL
Chromosome_number          42
Comment                    · indicates a break at the centromere.
                           In the example above, the 
                           translocation chromosome consists 
                           of the short arm of chromosome 1A 
                           translocated to the long arm of 1R 
                           with the breakpoint at the 
                           centromere.

The following example is of an actual translocation line of this
type and is how it appears in GrainGenes.

Germplasm                  Chinese Spring-A. intermedium 
                           Translocation T4DL·4Ai#2S
Abbreviation               CS-AGAI T4DL·4Ai#2S
Species                    Triticum aestivum
Donor_species              Agropyron intermedium
Type                       Translocation
Translocation_description  Terminal translocation with 
                           centromeric breakpoint
Derived_from               Chinese Spring
Chromosome_configuration   20"+1"T4DL·4Ai#2S
Chromosome_number          42
Developed_by               D. Wells
Development_site           South Dakota State University, Brookings
Comment                    The number sign (#) is used to 
                           distinguish between different 
                           chromosomes belonging to the same 
                           homoeologous group of 
                           chromosomes within accessions, as 
                           well as between accessions of the 
                           same species or cultivar.  In this 
                           example, the long arm of T. 
                           aestivum chromosome 4D (4DL) is 
                           translocated with a centromeric 
                           breakpoint (·) to the short arm (S) of 
                           an A. intermedium chromosome 
                           (4Ai#2S)

TERMINAL TRANSLOCATION WITH NON-CENTROMERIC BREAKPOINT
Germplasm                  Chinese Spring-Imperial Translocation 
                           T1AS·1AL-1RL
Abbreviation               CS-I T1AS·1AL-1RL
Species                    Triticum aestivum
Donor_species              Secale cereale cv. Imperial
Type                       Translocation
Translocation_description  Terminal translocation with non-
                           centromeric breakpoint
Derived_from               Chinese Spring
Chromosome_configuration   20"+1"T1AS·1AL-1RL
Detailed_abbreviation      CS-I T1AS·1AL1.4::1.21RL
Chromosome_number          42
Comment                    - and :: indicate a break and
                           rejoining within the arm.
                           In the example above, the 
                           translocation chromosome consists 
                           of the short arm of wheat 
                           chromosome 1A, a segment of the 
                           long arm of 1A with the breakpoint 
                           in band 1AL1.4 and a distal segment 
                           derived from 1RL with the 
                           breakpoint in band 1RL1.2.

INTERCALARY TRANSLOCATION WITH NON-CENTROMERIC BREAKPOINT
Germplasm                  Chinese Spring-Imperial Translocation 
                           Ti4AS·4AL-6RL-4AL
Abbreviation               CS-I Ti4AS·4AL-6RL-4AL
Species                    Triticum aestivum
Donor_species              Secale cereale cv. Imperial
Type                       Translocation
Translocation_description  Intercalary translocation with non-
                           centromeric breakpoint
Derived_from               Chinese Spring
Chromosome_configuration   20"+1"Ti4AS·4AL-6RL-4AL
Detailed_abbreviation      CS-I Ti4AS·4AL1.2::6RL-2.7::4AL
Chromosome_number          42
Comment                    Ti = an intercalary translocation.

TRANSLOCATION WITH UNKNOWN BREAKPOINT
Germplasm                  Triticum araraticum Translocation
                           T4G/5G
Abbreviation               CS-TARA T4G/5G
Species                    Triticum aestivum
Donor_species              Triticum araraticum
Type                       Translocation
Translocation_description  Translocation with unknown 
                           breakpoint
Derived_from               Chinese Spring
Chromosome_configuration   20"+1"T4G/5G
Chromosome_number          42
Comment                    / = unknown breakpoint

DELETION 
CHROMOSOMES                del 
Germplasm                  Chinese Spring Deletion 1AS-1
Abbreviation               CS del1AS-1
Species                    Triticum aestivum
Type                       Deletion
Derived_from               Chinese Spring
Chromosome_configuration   20"+1"del1AS-1
Detailed_abbreviation      CS del1AS-1(S1.2,0.17:)
Chromosome_number          42
Comment                    : = terminal deletion.
                           Numbers in detailed abbreviation 
                           indicate C-band where deletion 
                           occurs and fraction length of 
                           chromosome remaining.

REFERENCES

Gill BS (1986) A proposal for wheat chromosome band nomenclature. In: North American Wheat Genetic Mapping and Cytogenetic Stocks Workshop, April 17-19, 1986, University of Missouri, Columbia. Ed: Qualset CO and McGuire PE. The National Association of Wheat Growers Foundation, Washington, D.C. 11-15.

Gill BS, Friebe B, and Endo TR (1991) Standard karyotype and nomenclature system for description of chromosome bands and structural aberrations in wheat (Triticum aestivum). Genome 34: 830 - 839.

Kimber G and Sears ER (1968) Nomenclature for the description of aneuploids in the Triticinae. In: Proc 3rd Int Wheat Genet Symp, Ed: Findlay KW and Shepherd KW. Canberra, Australia. 468-473.

Sears ER (1954) The aneuploids of common wheat. Research Bull. 572, Missouri Ag. Exp. Sta. 57 p.


APPENDIX I. GRAINGENES ?Germplasm model

The following fields are currently available for use in the germplasm model for the description of genetic stocks. 

?Germplasm      
Other_name ?Germplasm XREF Other_name // Put data in only one.
Species UNIQUE ?Species
Donor_species ?Species  //For addition chromosomes
Type #Germplasm_type
Collection_and_ID ?Collection ?Germplasm XREF Other_name
Cross_number ?Text      //Identifier used by CIMMYT
Chromosome_configuration ?Text
Abbreviation ?Germplasm XREF Full_name
Full_name ?Germplasm XREF Abbreviation
Pairing_configuration ?Text
Chromosome_number ?Text //Not Int. "42tt" = ditelosomic substn.
Female_Parent UNIQUE ?Germplasm
Male_Parent UNIQUE ?Germplasm
Pedigree UNIQUE ?Text
Market_Class ?Text
Trait_study ?Trait_Study
Pathology ?Pathology XREF Resistant_line
Allele ?Allele  //No XREF
Gene ?Gene      //No XREF
Rearrangement    ?Rearrangement XREF Germplasm
Derived_from ?Germplasm
Developed_by ?Text
Development_site ?Text
Date_of_release ?Text
Registration_No ?Text
Remark ?Text
Reference ?Reference XREF Germplasm
Mapping_data ?Map_Data
Image ?Image XREF Germplasm
Data_source ?Colleague ?Text //Text is date, e.g. 93.08.27
Polymorphism ?Polymorphism
Trait_scores ?Trait_scores//could be a long list.
Coefficient_of_parentage ?Germplasm Float //Must be at end of
        //model; this could be a Long list.