Copyright 0 1986 by the Genetics Society of America

LINKAGE RELATIONSHIPS IN WILD EMMER WHEAT, TRITICUM DICOCCOIDES

EDWARD M. GOLENBERG'

Department of Ecology and Evolution, State University of New York, Stony Brook, New York 11 794 , and Institute of Evolution, University of H a f a , Israel 31999

Manuscript received February 18, 1985 Revised copy accepted August 7, 1986

ABSTRACT The linkage relationships in wild emmer wheat, Triticum dicoccoides, between

nine enzymatic loci (Mdh-1, Ipo, P-Glu, Pept-1, P e p - 3 , Est-5, Est-1, 6Pgdh-2 and Hk) and a coleoptile pigment locus (Rc) were investigated. Chromosome locations of genes were inferred from analysis of ditelocentric lines of Triticum aestivum, cultivar Chinese Spring. The loci Mdh-Bl and Hk are linked (lambda = 0.1869) and are most likely located on the chromosome IB. The loci P e p - B l and Rc are linked (lambda = 0.2758) and are located on the 6Bq chromosomal arm. Rc also has significant interactions with the loci Pept-3 and Ipo, although there is no significant linkage detectable. The interactions may be a result of epigenetic interactions. Est-1 has only one active product in T. dicoccoides and is most likely located on the 3Ap chromosome arm. No significant interactions were found for the remaining loci.

ITICUM dicoccoides, the wild progenitor of cultivated emmer wheat, shows T" considerable variability across its range in Israel, with the average per- centage of polymorphic loci per population being 0.25 (range 0.16-0.38) based on electrophoretically tested loci (NEVO et al. 1982). Many alleles at these loci have been shown to be associated with climatic factors (NEVO et al. 1982) and with alleles purported to confer resistance to stem and leaf rusts (NEVO et al. 1986; MOSEMAN et al. 1985) and powdery mildew (MOSEMAN et al. 1984). In view of the low rate of outcrossing (NEVO et al. 1982) and limited gene flow per generation (ZOHARY 1969)) it is important that the genetic relationships between many of these loci be determined. Such information would allow both direct genetic analysis of correlated traits and tracking of chromosomes or chromosome segments after interspecific or intervarietal crosses (AINSWORTH 1983). This report presents data concerning the linkage relationships between loci encoding for nine electrophoretically distinguishable enzymes (malate de- hydrogenase- l , indophenol oxidase (leaf tissue), &glucosidase, peptidase-l , pep- tidase-3, 6-phosphogluconic acid dehydrogenase-2, hexokinase, esterase-5 and esterase- 1) and a coleoptile pigment locus.

' Present address: Department of Botany and Plant Sciences, University of California, Riverside, California 92527.

Genetics 114 1023-1031 November, 1986.

1024 E. M. GOLENBERG

TABLE 1

Genotypes of parental plants

Parental origin

Loci Yehudiyyah Qazrin ~

Mdh-1 aa bb IPO aa bb P-Glu aa bb Pept- 1 aa bb Est-5 aa bb Est-1 bb aa P e p - 3 bb aa 6Pghd-2 bb aa Hk bb aa Rc bb aa

In the case of isozyme loci, a indicate alleles encoding for al- lozymes with faster electrophoretic mobility than those of b. For Rc, a and b indicate alleles encoding for the presence and absence of coleoptile anthocyanin, respectively. The isozyme allele assign- ments have been modified slightly from those in NEVO et al. (1 982).

MATERIALS AND METHODS

The Yehudiyyah and Qazrin populations of T. dicoccoides [see NEVO et al. (1982) for locations] are fixed for alternative alleles at eight of the above-mentioned loci (Mdh-I, Ipo, P-Glu, Pept-1, Pept-3, 6-Pgdh-2, Hk and Rc). Yehudiyyah is fixed for the EST-5 genotype aa aa, whereas Qazrin is marginally polymorphic with genotypes bb aa (94%), aa aa, and aa cc. [Genotype nomenclature has been modified from that in NEVO et al. (1982).] In contrast, Qazrin is fixed for EST-1 allele a, whereas Yehudiyyah is poly- morphic for alleles a and 6. Seeds from three separate parents were chosen from the Yehudiyyah (nos. Y-36, Y-42 and Y-46) and Qazrin (nos. Q-31, Q-35 and (2-48) pop- ulations in order to be genotypically identical within populations for the ten loci under question. The genotype for each population is listed in Table 1. The seeds were ger- minated and then planted in 8-inch pots and grown in a greenhouse under a 12-hr daylight photoperiod. After I month, the photoperiod was changed to a 16-hr light/8- hr dark cycle.

Upon flowering, the following crosses were made: Y-46 X Q-31, Q-35 X Y-42 and 4-48 X Y-36. The F1 seeds were then planted. The parental genotypes as well as the multiple heterozygous state of the progeny were verified by electrophoresis of the leaf tissue. Two seedlings from the Y-46 X 4-31 cross, two from the 4-48 X Y-36 cross and five from the Q-35 X Y-42 cross were subsequently grown and allowed to self. The F2 seeds were then germinated and typed by observation (pigment color) and by electrophoretic analysis of fresh leaf tissue.

Three buffer systems were used for the starch gels (12% Electrostarch): (1) LiOH; buffer A (tray)-0.03 M LiOH, 0.19 M boric acid; buffer B-0.05 M Trisma base, 0.008 M citric acid; gel buffer-1:9 solution A to B (IPO, 8-GLU); (2) 0.135 M Trisma base, 0.043 M citric acid adjusted to pH 7.0; gel buffer-1:15 dilution (MDH-1, EST- 5, EST-I); and (3) 0.1 M maleic acid, 0.1 M Trisma base, 10 mM Na2EDTA, 10 mM MgC12 adjusted to pH 7.4; gel buffer 1 2 0 dilution (6-PGDH-2, HK, PEPT-1, PEPT- 3). Assay techniques were as in NEVO et al. (1982), except for the systems PEPT and @-GLU. For PEPT, phenylalanylalanine was used as a substrate. The isozyme PEPT-3, not reported previously in NEVO et al. (1982), appeared with the use of the new

LINKAGE IN TRITICUM DICOCCOIDES 1025

= - = - m - - - - GENOME 1 2 1+2 1 2 1+2 1+2

PRRENT R PRRENT B F1 CROSS FIGURE 1 .-Hypothetical zymogram showing the problem of electrophoretic dominance in

interpretation of monomeric allozyme patterns in tetraploids. Both parents are tetraploids with genomes I and 2. The isozyme produced by the gene located in genome I is monomorphic. The gene producing the isozyme in genome 2 is polymorphic. The allozymes have fast and slow mobilities such that the slower allozyme overlaps the isozyme produced from genome I as can be seen in parent B. The F, offspring of the cross between A and B has an electrophoretic pattern identical to parent A. Thus, parent A has an electrophoretic phenotype that is dominant over the phenotype of parent B.

substrate and was anodal to PEPT-1. For 8-GLU, 4-methylumbelliferyl-~-~glucoside was used as a substrate, and isozyme activity was detected under ultraviolet light. Greater resolution was achieved by this method, and two polymorphic isozymes could be read.

As T. dicoccoides is an allotetraploid (AABB), any given enzyme may be encoded by two loci, one present in each genome. This leads to two complications in the interpre- tation of the electrophoretic results. First, monomeric allozymes encoded by one poly- morphic locus may have the same electrophoretic mobility as those produced by a monomorphic, homologous locus in the second genome. Thus, two electrophoretic phenotypes may be distinguished: one with two bands where the products of both loci are distinguishable and a second with a single band where the products of the homol- ogous loci overlap. An F1 offspring from crosses of parents having such phenotypes would produce a two-banded phenotype similar to the two-banded, homozygous parent, even though it is heterozygous at the polymorphic locus (Figure 1). Thus, because of the masking interaction of the monomorphic locus, loci encoding for such isozymes would show electrophoretic epistasis. Analysis of the polymorphic locus would be based on a type of dominance, however, as heterozygotes and double-banded homozygotes are indistinguishable. This applies to the loci Mdh-I , Pept-I and Hk.

The second problem arises in systems in which both loci are polymorphic and par- ticular genotypes produce overlapping electrophoretic patterns. In such instances, gen- otypes may not be unequivocably scored for both loci. P-Glu is such a case. One locus produces a scorable allele in Yehudiyyah genotypes but has a null allele in Qazrin genotypes. The second locus is also polymorphic (modal allele in Yehudiyyah and a fast allele in Qazrin); however, in many of the F2 individuals it could not be read with complete certainty because of overlap with the Yehudiyyah allele in the first system. As a result, only the first locus is studied in this report.

The isozymes IPO, PEPT-3, EST-1 and 6-PGDH-2 appear to have only one active contribution from the two genomes. Only one isozyme band is apparent with these systems. This is true in all individuals tested regardless of the mobility of the enzyme, thus largely ruling out the possibility of overlap and masking of a second genomic product. The second genomic locus is assumed either to be silenced or to have under- gone mutation to a nonactive state. Of these loci, Pept-3 cannot be unequivocably scored for heterozygotes because of partial overlap of the products of the two alleles. Similarly, the Rc locus could be scored only for presence or absence of anthocyanin. Thus, of the ten loci studied here, only Est-1, Est-5, Ipo and 6-Pgdh-2 were scored for codominant alleles. All other loci were scored with phenotypic dominance. (Photographs of gels or zymograms of all systems are presented in Figures 2 through 8.)

The zygotic distribution for all two-locus pairs were tested for evidence of disturbance of segregation ratios in each locus and of linkage by the method of orthogonal contrasts. The orthogonal contrasts for two loci showing dominance both in coupling and in repulsion phase for intercross data may be found in ELANDT-JOHNSON (1971). The

1026 E. M. COLENBERC

2 v v v

- 5

6

!

FIGURE 2.-Photograph of a gel stained for EST activity. In EST-5 (upper group of bands), the individuals 1 and 2 are homozygous for the allele a (encoding for the fast allozyme). Individual 10 is homozygous for the allele b (encoding for the slow allozyme). Individual 3 is heterozygous. In EST-1 (lower group of bands), individual 1 is homozygous for the allele b, individual 3 is homozygous for the allele a and individual 2 is heterozygous.

FIGURE 3.-Photograph of a gel stained for leaf tissue IPO activity. Individual in slot 1 is homozygous for the b allele, individual 2 is homozygous for the allele a and individual 5 is a heterozygote.

FIGURE 4.-Cel stained for MDH activity. Two systems are apparent. MDH-2 (second group of bands) is monomorphic between the tested populations. MDH-1 (topmost group of bands) displays electrophoretic dominance as described in the text and in Figure 1. Individuals 3 and 4, for example, are homozygous for the 'recessive" allele b. Individuals 1 and 2 have the dominant allele a.

FIGURE 5.-CeI stained for BPGDH activity. 6-PGDH-1 is monomorphic between these popu- lations. 6-PGDH-2 has two alleles in these two populations. The allozyme encoded by the allele b has a slow mobility and is accompanied by a shadow band. Individuals 7 and 8 are examples of homozygotes for this allele. Individual 4 is an example of a homozygote for allele a encoding for the faster allozyme. Individuals 3. 5 and 6 are examples of heterozygotes and may be distinguished by the equal intensity of the bands.

FIGURE 6.-Cel stained for HK activity. At least two hexokinase isozymes are apparent, both staining very lightly. In the photograph, individuals 2. 3 and 5 are homozygous for the a allele. Individuals 4 and 6 are homozygous for the b allele.

FIGURE 7.--Gel stained for PEPT activity. Three isozyme regions are distinguishable. PEPT-2 has the slowest mobility and is monomorphic in the tested populations. PEPT-1 is composed of two independent isozymes encoded from two homologous genes. The more mobile isozyme is monomorphic here. The second, polymorphic isozyme has fast and slow allozymes corresponding to the a and b alleles. Homozygous 00 may be distinguished from the banding patterns as in individuals 4 and 12, for example. As explained in Figure 1, genotypes bb and ab cannot be unequivocably distinguished. Individuals 5 through 11 are examples of this class of phenotypes. PEPT-3 is anodal to PEPT-1 and has slow (e.g., individuals 1-3) and fast (e.g., individuals 4-1 1) allozymes.

orthogonal contrasts and the variances for dominant-codominant and codominantco- dominant two-locus pairs are listed in Table 2. For those pairs of loci that had significant values of x 2 for interaction, the recombination fraction, lambda and its standard er- ror were estimated using the maximum likelihood functions (ELANDT-JOHNSON 197 1; ROBINSON 197 1 ).

LINKAGE IN TRITICUM DICOCCOIDES 1027

FIGURE 8.-Zymogram of a 8-GLU gel. Two overlapping systems appear. One system has two allozymes that stain as single strong bands. The first and fourth examples in the drawing are homozygous for the allele encoding for the fast allozyme. Individuals 2, 3 and 5 are homozygous for the “slow” allele. The second system is represented by a null (6) allele, as in individuals 1 and 4, and an allele encoding for a composite electrophoretic pattern of five bands (U). The structure of the enzyme involved is not clear; however, the five-banded pattern appears to be allelic and segregates in a Mendelian fashion.

TABLE 2

Orthogonal contrasts for detection of linkage from intercross AaBb X AaBb

Dominantcodominant loci Codominant-codominant loci

Contrasts Contrasts

Phenotype Weight A us. a B us. b Linkage Phenotype Weight A vs. a B vs. b Linkage

A-BB 3/16 1 1 1 AABB A-Bb 6/16 1 -1 -1 AABb A-bb 3/16 1 1 1 AAbb aaBB 1/16 -3 1 -3 AaBB aaBb 2/16 -3 -1 3 AaBb aabb 1/16 -3 1 -3 Aabb

aaBB Variance 3N N 3N aaBb

aabb

1/16 1 1 1 2/16 1 -1 -1 1/16 1 1 1 2/16 -1 1 -1 4/16 -1 -1 1 2/16 -1 1 -1 1/16 1 1 1 2/16 1 -1 -1 1/16 1 1 1

Variance N N N

Seeds of ditelocentric accessions of the Chinese Spring cultivar of the hexaploid Triticum aestivum were germinated and analyzed electrophoretically using the same assay techniques as listed above. Ditelocentric accessions were not available for lop, ZAq, 2Bp, 4Aq, 4Bp, 5Ap, 5Bp or 7Dq. The electrophoretic zones of activity of the T. aestivum isozymes were compared to those of T. dicoccoides to infer homology. In addition, the isozyme patterns were scrutinized for absence of bands associated with specific ditelo- centric accessions. The absence of a particular isozyme band in accessions lacking par- ticular chromosomal arms was used to infer the location of the locus encoding for that isozyme (HART 1979). These results were used to compare and identify the isozyme loci reported herein with previously published enzyme loci in T. aestivum.

RESULTS

Sixty-four F2 seeds were successfully germinated and genetically typed. Two loci, Rc and P-Glu, displayed significant deviations from the 0.50, 0.50 ex- pected frequencies, with frequencies of the two alleles being 0.60 and 0.40 and 0.61 and 0.39, respectively. All other loci did not differ significantly from the expected frequencies.

Forty-five two-locus pairs were tested for interaction. Significant interactions were found for Mdh-1 and Hk (x2 = 12.25, P < 0.001), Rc and Pept-1 (x2 = 7.11, 0.01 < P < 0.005), Rc and Pept-3 (x2 = 4.59, 0.05 < P < O.Ol), Rc and Est-1 (x2 = 8.33, 0.05 < P < 0.01) and Rc and Ipo (x2 = 12.00, P < 0.001). Since the allelic ratio at the Rc locus was abnormal, these linkage tests may

1028 E. M. GOLENBERG

TABLE 3

Interaction XI, recombination fractions and standard error for loci displaying significant interactions?

Recombination Loci Y e fraction SE

Mdh-1 -Hk 12.25*** 0.1869*** 0.1006 Pept-I-Rc 7.11** 0.2758* 0.0677 Pept-3-Rc 4.59* 0.3436 (NS) 0.0768 I~Io-Rc 12.00*** 0.3633 (NS) 0.0716

* 0.01 < P < 0.05; ** 0.001 < P 0.01; *** P < 0.001; (NS), nonsignifi- cant.

not be totally reliable (ROBINSON 1971). The expected genotypic weights were replaced by those actually shown by the data. The interaction between the Rc and Est-1 loci became nonsignificant (x2 = 5.27), whereas those between Rc and the loci Zpo, Pept-1 and Pept-3 still displayed significant interactions.

Recombinant fractions, lambda, and their standard errors are listed for the four pairs of loci showing significant interaction (Table 3). Of the four, only two pairs, Mdh-1-Hk (A = 0.1869) and Pept-l-Rc (A = 0.2758) have recombi- nation fractions significantly different from 0.5.

The analysis of the Chinese Spring cultivar of T. aestivum was executed in order to identify clearly the T. dicoccoides isozymes studied here with isozymes of the cultivated hexaploid wheats. Ditelocentric accessions produced electro- phoretic patterns lacking specific bands for PEPT-1, EST-1 and MDH-2 (Fig- ures 9-1 1). The chromosomal locations were thus inferred. Pept-1 studied herein was located on the 6Aq and 6Bq arms of Chinese Spring (GOLENBERG 1986). No active gene product was noticeable from the 4D chromosome in this study; the banding patterns for T. aestivum and T. dicoccoides were identical for PEPT-1. In a similar manner, Est-I was located on the 3q chromosome. Active gene products could be deduced from the 3A and 3D chromosomes. No active product was apparent from the B genome. Mdh-1 could not be unequivocably located, however Mdh-2, not used in the genetic analysis in this study, was located on chromosome arm l q .

DISCUSSION

Chromosomal locations of several electrophoretic loci have been reported for T. aestivum (MCINTOSH 1983). HART (1973) and HART and LANGSTON (1977) have reported Amp-1 to be located on the 6Ap and 4Bp arms. In ad- dition, HART (MCINTOSH 1983) has reported an Amp-1 locus on 6Dp. On the basis of assay procedure, these AMP isozymes are equivalent to the LAP iso- zymes reported in NEVO et al. (1982). Similarly, Ep loci have been reported by HART and LANGSTON (1977) to be situated on the group 7 chromosomes. Thus, the Pept-1 loci reported above are not homologous with the Amp and Ep loci previously reported (GOLENBERG 1986).

The Est-1 results only roughly correspond with previously published results (AINSWORTH GALE and BAIRD 1984; BARBER et a l . 1968). BARBER et al . (1968)

LINKAGE IN TRITICUM DICOCCOIDES 1029

r 8

t L

FIGURE 9.--Gel with samples of ditelocentric lines of T. oestivum var Chinese Spring stained for PEPT activity. Sample 2 is CSDTGAS and displays a deviant isozyme pattern in PEPT-1, with the fast allozyme band being absent. Sample 4. CSDTGBS displays a complementary pattern, with the slower allozyme band being absent.

FIGURE 10.-Gel with samples of ditelocentric lines of T. acslivum var Chinese Spring stained for EST activity. Samples 1 and 2, and 3 and 4 (paired samples of CSDTJAS and CSDTSDS, respectively), display deviant isozyme patterns in EST-1 with slower and faster allozymes missing, respectively.

FIGURE 1 1.-Gel with samples of ditelocentric lines of T. acslivum var Chinese Spring stained for MDH activity. Samples 7 and 8 (paired samples of CSDTlBS) display obvious deviant allozyme patterns in MDH-2.

FIGURE 12.-Gel with samples of T. dicoccoides stained for MDH activity. Sample 2 displays a rare slow allozyme in MDH-2 occurring coincidentally with the common allozyme (heterozygous a t Mdh-2). Both allozymes display the common two-banded phenotype, while n o heterodimeric band is apparent.

report Est-Z loci on 3Ap, 3Bp and 3Dp. Other esterase loci, Est-5 on 3A9, 3B9 and 3D9 (AINSWORTH 1983), Est-2 also on 3A9, 3B9 and 3D9 (JAASKA 1980), Est-3 on 7Bp and 7Dp (JAASKA 1980), and Est-4 on 6A9, 6B9 and 6D9 (JAASKA 1980), have been reported. As no clear results were obtained from the ditel- ocentric accessions tested concerning the location of Est-5 reported here, its relationship to previously reported Est loci is uncertain. Similarly, the different positions of the Est-Z reported here and previously by BARBER et al. (1968) clearly indicate that these are not the same loci. It is possible that the Est-Z of this report corresponds with Est-5 (AINSWORTH 1983) or with Est-2 (JAASKA 1980), all of these loci being located on the long arms of the homologous set of chromosome 3. Therefore, it is important to note that the nomenclature of the esterase loci proffered here is meant only to correspond with the esterase isozymes reported in NEVO et al. (1 982) and does not correspond or supercede published esterase gene nomenclature (AINSWORTH GALE and BAIRD 1984).

T w o MDH active staining regions have been previously reported (BENITO and SALINAS 1983). BENITO and SALINAS (1 983) have assigned a locus encoding the dimeric enzyme MDH-I1 to the long arms of chromosomes ZA, 1B and ID. HART (1 984) lists these loci as Mdh-1. The second active system, MDH-I, could not be associated with an encoding locus with a known chromosomal location (BENITO and SALINAS 1983). The Mdh-Z location could not be reverified di-

1030 E. M. GOLENBERG

rectly in this study. However, the enzyme involved does appear to be dimeric; therefore, it may be identical to that reported by BENITO and SALINAS (1 983) and HART (1984). The MDH-2 enzyme reported here is not dimeric. Related diploids (Triticum boeticum, Aegilops speltoides) produce similar two-banded elec- trophoretic patterns. In addition, individuals of T. dicoccoides that are hetero- zygous for rare MDH-2 variants display no heterodimeric banding (Figure 12). Thus, there is preliminary evidence that both sets of MDH encoding loci may be located on chromosome set 1 . AINSWORTH (1983) has reported a structural gene encoding the enzyme hexokinase, Hk-1, to be on the short arm of chro- mosome 1B. As Mdh-1 and Hk are shown to be linked in T. dicoccoides, it is probable that these two loci are those reported by HART and AINSWORTH. Barring translocation and inversion, these two loci are most likely located on chromosme 1B in T. dicoccoides. [AINSWORTH (1983) also reports Hk loci to be located on chromosome 3; however, as there is no evidence of an Mdh locus on chromosome 3, linkage to this locus is considered less likely.]

A similar analysis may be made concerning the coleoptile pigment locus reported in this study. Coleoptile anthocyanin loci have been reported on chromosomes 7 A ( R c l ) , 7Bp (Rc2) and 7Dp (Rc3) in T. aestivum and Ae. squar- rosa (genome 0) [see MCINTOSH (1983) for references]. In addition, a fourth locus has been reported on chromosome 6 B (SUTKA 1977). As the pigment locus reported here is linked to Pept-1, and Pept-1 loci are located on chro- mosome arms 6Aq and 6Bq, it appears that the pigment locus is homologous to Rc reported by SUTKA. Again, barring translocation and inversion, the var- iable Pept-1 locus and Rc are probably located on chromosome arm 6Bq.

The significant interaction found between Rc and the loci Pept-3 and Ipo and the lack of interaction between the latter among themselves and with Pept- 1 may be indicative of an epigenetic interaction rather than true linkage (ROBINSON 1971). The deviation of the distribution of the Rc alleles from the expected may be derived from a partial inviability. This cannot, however, be partial inviability of either the recessive or dominant allele in a simple sense. Both alleles naturally occur in the homozygous state, and the deviations show an excess of parental genotypes (coupling) in relation to Ipo and Pept-3. Thus, the partial inviability may be related to repulsion gametes. The development of gametic phase disequilibria between these loci in F3 and subsequent gener- ations warrants further observation.

Contribution no. 602 in Ecology and Evolution from the State University of New York at Stony Brook. This research was supported in part by a grant-in-aid from Sigma Xi and by the Ancell- Teicher Research Foundation for Genetic and Molecular Evolution established by Florence and Theodore Baumritter of New York. I am grateful to G. KIMBER for generously supplying the ditelocentric lines of Chinese Spring. I should like to thank E. NEVO, B. LAVIE, A. BEILE~ and an anonymous reviewer for commenting on the manuscript. I should like especially to thank E. NEVO for his continuous support.

LITERATURE CITED

AINSWORTH, C. C., 1983 The genetic control of hexokinase isozymes in wheat. Genet. Res. 42: 219-227.

LINKAGE IN TRITICUM DICOCCOZDES 1031

AINSWORTH, C. C., M. D. GALE and S. BAIRD, 1984 The genetic control of grain esterases in

BARBER, H. N., C. J. DRISCOLL, P. M. LONG and R. S. VICKERY, 1968 Protein genetics of wheat

BENITO, C. and J. SALINAS, 1983 The chromosomal location of malate dehydrogenase (E.C.

ELANDT-JOHNSON, R. C., 1971 Probability Models and Statistical Methods in Genetics. John Wiley,

GOLENBERG, E. M., 1986 Chromosomal location of peptidase, P e p - I , genes in Triticum aestiuum var Chinese Spring. Genet. Res. In press.

HART, G. E., 1973 Homoeologous gene evolution in hexaploid wheat. pp. 805-810. In: Proceed- ings of the 4th International Wheat Genetics Symposium.

Genetical and chromosomal relationships among the wheats and their rela- tives. Stadler Genet. Symp. 11: 9-29.

Biochemical loci of hexaploid wheat (Triticum aestiuum, 2n=42, genomes AABBDD). In: Genetic Maps 1984, Vol 3 , Edited by S. J. O’BRIEN. Cold Spring Harbor Laboratory, Cold Spring Harbor, New York.

Chromosomal location and evolution of isozyme structural genes in hexaploid wheat. Heredity 39, 263-277.

Electrophoretic survey of seedling esterases in wheat in relation to their phy- logeny. Theor. Appl. Genet. 5 6 273-284.

A catalogue of gene symbols for wheat (1983 edition). pp. 1197-1254. In: Proceedings of the 6th International Wheat Genetics Symposium (Kyoto, Japan, 1983)

Resistance of Triticum dicoccoides to infection with Erysiphe graminis tritici. Euphytica 33: 41-47.

1985 tritici Crop. Sci. 25: 262-265.

Resistance of wild wheat to stripe rust: predictive method by ecology and allozyme genotypes for stripe and stem rusts. Plant Syst. Evol. 153: 13-30.

NEVO, E., E. GOLENBERG, A. BEILES, A. H. D. BROWN and D. ZOHARY, 1982 Genetic diversity and environmental associations of wild wheat, Triticum dicoccoides, in Israel. Theor. Appl. Genet. 6 2 241-254.

hexaploid wheat. Theor. Appl. Genet. 68: 219-226.

and homologous relationships of chromosomes. Nature 218: 450-452.

1.1.1.37) isozymes in hexaploid wheat (Triticum aestiuum). Euphytica 32: 783-790.

New York.

HART, G. E., 1979

HART, G. E., 1984

HART, G. E. and P. LANGSTO~, 1977

JAASKA, V., 1980

MCINTOSH, R. A., 1983

MOSEMAN, J. G., E. NEVO, M. A. EL-MORSHIDY and D. ZOHARY, 1984

MOSEMAN, J. G., E. NEVO, Z. K. GERECHTER-AMITAI, M. A. EL-MORSHIDY and D. ZOHARY, Resistance of Triticum dicoccoides collected in Israel to infection with Puccinia recondita

NEVO, E., Z. GERECHTER-AMMITAI, A. BEILES and E. M. GOLENBERG, 1986

ROBINSON, R., 1971 Gene Mapping in Laboratory Mammals, Part A. Plenum Press, London.

SUTKA, J., 1977 The association of genes for purple coleoptile with chromosomes of the wheat variety Mironovskaya 808. Euphytica 2 6 475-479.

ZOHARY, D., 1969 The progenitors of wheat and barley in relation to domestication and agri- cultural dispersal in the old world. In: The Domestication and Exploitation of Plants and Animals, Edited by P. J. UCKO and G. W. DIMBLEY. Duckworth, London.

Communicating editor: W. F. SHERIDAN