The falcifolia syndrome of Oenothera: IV. Loss of falcifolia-determining factors

Summary Inheritance of the falcifolia syndrome is explained by the hypothesis that this developmental disturbance is caused by the interaction of a non-chromosomal determinant (sigma) of Oenothera suaveolens with a complementary determinant (lambda) of O. lamarckiana when these two species are crossed. Localization of the determinants in the cell, the mechanism of their expression, and their molecular nature have not been established. Somatic segregation within the hybrids may lead to a separation of the two components, as suggested by the different reactions of sister plants in backcross tests and on selfing. The present paper presents results showing that in rare cases the fal determinants may be eliminated from the hybrid's cytoplasm. Thus, plants are produced that are phenotypically identical with the original parental strains but in crosses react like species that lack such determinants.     

Development of polarity in the ovules of the F2-progeny of theOenothera hybridalbicans · hhookeri

In the F₂-progeny of hybrids from crosses betweenOenothera biennis orsuaveolens andOe. hookeri with theRenner-complexesalbicans and^hhookeri, the development of callose pattern in meiocytes and megaspore tetrads is the same as in the F₁ and the parentOe. hookeri. During the development of the megaspore tetrads and the embryo sacs primary and secondary heteropolarity as well as homopolarity is observed. Estimates for the initial frequency of homo- and heteropolar tetrads at the end of the degeneration of megaspores in the tetrads immediately before the start of embryo sac development could be calculated. The F₂-plants can be arranged in three groups, distinguished by the frequency of the two polarity types. One of these groups behaves similar to the parentOe. hookeri, the two others have more homopolar tetrads. The segregation can be interpreted as recombination of genes, which influence the development of the polarity in the ovules. This is possible by crossing-over of genes between the twoRenner-complexes of the hybrid.     

The falcifolia syndrome of Oenothera: III. The general pattern of its non-Mendelian inheritance

Summary The falcifolia (fal) syndrome is a malformation characterized by shoot sectors with sickle-shaped leaves, which appears in hybrids between Oenothera suaveolens and O. lamarckiana and shows a non-chromosomal inheritance of a previously undescribed type. The determinants, their location in the cell, and the mechanism of their expression are unknown. The defect is the result of a cross in which mixing of two different cytoplasms occurs, without the usual predominantly maternal inheritance. F₁ progeny of reciprocal crosses show a quantitative difference in the frequency and degree of expression of the fal character. When the F₁ progeny are backcrossed to the parents, the percentage of fal is high in crosses to O. suaveolens and low in those to O. lamarckiana. This manner of transmission is observed regardless of whether the hybrid is used as seed or pollen parent or shows a normal or fal phenotype. F₂ generations from F₁ plants having either a normal or a fal phenotype always include a certain percentage of fal plants, although the latter generally produce a higher percentage of fal progeny. If a second backcross is carried out, plants that produce normal progeny on self-pollination behave differently from those that produce some fal off-spring when selfed. The latter are similar to the F₁ with regard to the transmission of the fal trait. Plants of the F₁B₁ yielding normal progeny upon selfing produce normal progeny in the F₁B₂ if the parent to which they are backcrossed is the same as in the first backcross; if the parents of the first and second backcross differ, a high percentage of fal offspring is obtained. Again, whether the hybrid is used as seed or pollen parent is not relevant. Exceptions to this behaviour have been observed only rarely in that the character of the penultimate cross is retained. There is some evidence of somatic segregation of the fal determinants, since sister plants may react differently; this suggestion is supported by comparing the progenies of different branches of a self-pollinated fal plant of the F₁ generation.Abbreviations F₁, F₂, F₃, F₄ First through fourth filial generation, obtained by self-pollination - F₁B₁ First backcross generation, i.e. the F₁ was backcrossed to one of the original parents - F₁B₂ Second backcross generation, i.e. the F₁B₁ was backcrossed to one of the original parents - F₁B₃ Third backcross generation, i.e. the F₁B₂ was backcrossed to one of the original parents - (F₁B₁)D₁ Descendants obtained by self-pollination of a F₁B₁ plant; further generations obtained by self-pollination are designated as D₂, D₃, D₄ - (F₁B₁)D₁B₁ Descendant or generation obtained by a backcross of the D₁ of an F₁B₁. Backcrosses of the D₂ and D₃ are designated mutatis mutandis - (F₁B₁)D₁B₂ Generation obtained by a backcross of the (F₁B₁)D₁B₁     

Callose pattern and polarization phenomena in the ovules in the F2-hybrids betweenOenothera hookeri andOe. suaveolens

The pattern of callose formation in meiotic cell walls and the order of megaspore degeneration and polarity during embryo sac development are investigated in F₂-plants ofOe. hookeri ×suaveolens and the reciprocal cross. All investigated characters are variable between the ovules in the same ovary. Plants differ in the frequency of the types of callose pattern and polarity of the embryo sacs. In segregating progenies different combinations of both characters are found. The genetic basis of the polarity phenomena during the embryo sac development is discussed. In our material no correlation can be seen between the callose pattern in the surrounding wall of the meiotic cell and the development of polarity in the later stages.     

Dreifarbenpanaschierung beiOenothera II Wechselwirkungen zwischen Geweben mit zwei erblich verschiedenen Plastidensorten

Summary The true-breeding hybridOenothera albivelutina (albicans · velans) obtained by crossingOe. suaveolens × Oe. Lamarckiana is often variegated by plastids from the father: Thesuaveolens-plastids become green normally, while theLamarckiana-plastids become pale regionally in particular developmental stages. It is possible to replace the normalsuaveolens-plastids by mutated chlorophyll-deficient (yellowgreen) plastids. In the regions where theLamarckiana-plastids are getting pale we then observe, not only the expected variegation pale/yellow-green, but in addition normally green tissue too.Genetic analysis shows, that the green tissue does not represent a new idiotype, but its plastids areLamarckiana-plastids which have become green (instead of being pale) by the influence of neighbouring mutated yellow-greensuaveolens-plastids. The investigation of cross-sections through the leaves shows, that theLamarckiana-plastids become green only when cells with mutated plastids lie above or below them, but not when situated beside them in the same layer. In the latter case thelamarckiana-plastids are pale. In the entire leaf this intercellular effect of yellow-green plastids onLamarckiana-plastids is limited to the vertical direction. Only by exception cells in the same layer influence one another. It is assumed that this corresponds to a preferential transport of metabolites in the vertical direction.

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Mit 9 Textabbildungen     

Pollen tube expression of pseudo-self-compatibility (PSC) inPetunia hybrida

Summary AnS _1.1 self-incompatible (SI) petunia plant which showed atypical seed set was found in an I₇ population. This plant showed a strong SI reaction when selfed but produced varying amounts of seed when used as the seed parent in crosses with unrelated individuals homozygous for the sameS allele. Reciprocal crosses yielded no seed indicating that the reaction was a stylar response. Self seed obtained by high temperature treatments produced 18 plants, all of which exhibited the parental characteristics, the ability to reject self pollen but accept, to varying degrees, pollen bearing the sameS allele from unrelated plants. Several petunias homozygous forS ₁, and exhibiting various levels of PSC as determined by self seed set, progeny tests and temperature treatments, were used as pollen parents. The mean seed set of these crosses produced a ranking of the pollen parents which reflected the PSC levels obtained by other methods. The behavior of the F₁ and F₂ populations suggests that the pollen discriminating ability may be a simply inherited, dominant character in these plants. The styles of these unusual petunias illustrate the participation of the pollen tube in determining PSC.Scientific Journal Series Paper Number 10.479 of the Minnesota Agricultural Experiment Station     

Inheritance of somatic embryogenesis in red clover (Trifolium pratense L.)

 Red clover genotypes capable of regenerating plantlets in vitro from non-meristematic tissue-derived callus are rare. Selection for genotypes capable of somatic embryogenesis identified a clone comprised of a group of plantlets regenerated from a hypocotyl-derived callus culture on L2-based media and another group of plantlets originating from crown divisions of the epicotyl-derived plant. The callus-derived plants of this clone were highly regenerative when reintroduced to callus culture, but the epicotyl-derived plants produced nonregenerative callus cultures. F₁, F₂ and BC₁ populations were evaluated to determine the mode of inheritance of the regeneration trait. Reciprocal crosses did not differ, indicating a lack of maternal effects. Results were compatible with genetic control of regeneration by two complementary genes. We propose the genotype Rn1-Rn2- for regenerative plants. Three petiole segment explants were sufficient to evaluate regenerative ability in seedlings. Regenerative ability was often associated with abnormal leaf morphology in a few to several leaves. Received: 17 February 1998 / Accepted: 7 April 1998     

Inheritance of resistance to anti-microtubule dinitroaniline herbicides in an “intermediate” resistant biotype of Eleusine indica (Poaceae)

Inheritance of resistance to the anti-microtubule dinitroaniline herbicides was investigated in a goosegrass biotype displaying an intermediate level of resistance (I). Reciprocal crosses were made between the I biotype and previously characterized susceptible (S) or resistant (R) biotypes. Eight F₁ hybrids were identified, and F₂ populations were produced by selfing. The dinitroaniline-herbicide response phenotype (DRP) of F₁ plants, and F₂ seedlings was determined using a root-growth bioassay. The DRP of F₁ plants of S × I was “susceptible” (i.e., identical to the S parental plants), and the DRP of F₁ plants of I × R was “intermediate” (i.e., identical to the I parental plants). Nonparental phenotypes were not observed in F₁ plants. Results indicated susceptibility to be dominant over intermediate resistance and intermediate resistance to be dominant over high resistance. Analysis of reciprocal crosses ruled out any role for cytoplasmic inheritance. When treated at the discriminating concentration (e.g., 0.28 ppm oryzalin), F₂ seedlings of S × I were classified as either S or I phenotype, and F₂ seedlings of I × R were classified as either I or R phenotype. Again, nonparental phenotypes were not observed. The 3:1 (S:I or I:R) segregation ratios in F₂ seedlings were consistent across all eight F₂ families. The results show that dinitroaniline herbicide resistance in the I biotype of goosegrass is inherited as a single, nuclear gene. Furthermore, it suggests that dinitroaniline resistance in goosegrass is controlled by three alleles at a single locus (i.e., Drp-S, Drp-i, and Drp-r).     

Chromosomenreduktion in den Nachkommenschaften von autopolyploidem Rohrschwingel (Festuca arundinacea Schreb.)

Zusammenfassung Zur Herstellung amphipolyploider Art- und Gattungsbastarde mitFestuca arundinacea wurde ein autopolyploider Rohrschwingel erzeugt. Unter den Nachkommen dieser Pflanze treten Formen mit verminderter Chromosomenzahl auf. Trotzdem ist die Herstellung amphipolyploider Art- und Gattungsbastarde bei Chromosomenverdopplung vor Durchführung der Kreuzung leichter als eine erfolgreiche Behandlung der F₁-Pflanzen.

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Chromosome reduction in the offspring of autopolyploid tall fescue (Festuca arundinacea Schreb.)

Summary An autopolyploid tall fescue has been developed for use in the production of amphipolyploid intergeneric and interspecific hybrids. Plants with reduced chromosome numbers occur in the progeny of these dodecaploid plants. Nevertheless, it is easier to produce amphipolyploid intergeneric and interspecific hybrids by doubling of the chromosomes before making the cross than to treat successfully theF ₁-plants.

     

Dwarfism and male sterility in interspecific hybrids of Epilobium

Summary Reciprocal differences for male sterility, dwarfism and morphological traits have been studied in intra- and interspecific crosses of five Epilobium species. Male sterility occurred in two interspecific hybrids with E. montanum as the male parent while dwarfism has been found to varying degrees in three interspecific crosses with E. watsonni. In contrast to transient differences in plant height and leaf morphology in reciprocal hybrids of the cross between E. hirsutum and E. parviflorum, male sterility and dwarfism persistently occur as reciprocally different traits which may be influenced by determinants of the cytoplasm. The molecular characterization of the plastid DNA of the parental lines and the F₁ hybrids indicate that the plastome of male sterile and dwarf plants is identical to that of the female parents. Furthermore, in spite of these developmental disturbances, the expression of plastid genes coding for polypeptides of thylakoid-membrane complexes is unchanged. Thus, it seems unlikely that the genetic compartement of the plastids is responsible for the expression of the male sterile or the dwarfed phenotype.     

Genetic Analysis and Histological Study of Red Seed in Rice

Reciprocal crosses between red and achromatic rice revealed that the seed color of F₁ was determined by its female parent. According to the seed color and plant segregation ratio of F₁, F₂, and F₃ generations, the red phenotype of red double-haploid seed was determined by a dominant, monogene with maternal effect. Histological study showed that the red pigments accumulated in the pericarp layer only. The assay of developmental timing of pigment accumulation showed that the red color accumulated from desiccation stage to perfectly maturation stage of the seeds.     

Procedures for identifying S-allele genotypes of Brassica

Summary Procedures are described for efficient selection of: (1) homozygous and heterozygous S-allele genotypes; (2) homozygous inbreds with the strong self- and sib-incompatibility required for effective seed production of single-cross F₁ hybrids; (3) heterozygous genotypes with the high self- and sib-incompatibility required for effective seed production of 3- and 4-way hybrids.From reciprocal crosses between two first generation inbred (I₁) plants there are three potential results: both crosses are incompatible; one is incompatible and the other compatible; and both are compatible. Incompatibility of both crosses is useful information only when combined with data from other reciprocal crosses. Each compatible cross, depending on whether its reciprocal is incompatible or compatible, dictates alternative reasoning and additional reciprocal crosses for efficiently and simultaneously identifying: (A) the S-allele genotype of all individual I₁ plants, and (B) the expressions of dominance or codominance in pollen and stigma (sexual organs) of an S-allele heterozygous genotype. Reciprocal crosses provide the only efficient means of identifying S-allele genotypes and also the sexual-organ x S-allele-interaction types.Fluorescent microscope assay of pollen tube penetration into the style facilitates quantitation within 24–48 hours of incompatibility and compatibility of the reciprocal crosses. A procedure for quantitating the reciprocal difference is described that maximizes informational content of the data about interactions between S alleles in pollen and stigma of the S-allele-heterozygous genotype.Use of the non-inbred I_o generation parent as a known heterozygous S-allele genotype in crosses with its first generation selfed (I₁) progeny usually reduces at least 7 fold the effort required for achieving objectives 1, 2, and 3, compared to the method of making reciprocal crosses only among I₁ plants.Identifying the heterozygous and both homozygous S-allele genotypes during the I₁ generation facilitates, during subsequent inbred generations, strong selection for or against modifier genes that influence the intensity of self- and sib-incompatibility. Selection for strong self and sib incompatibility can be effective for both homozygous inbreds and also for the S-allele heterozygote, thus facilitating production of single-cross F₁ hybrids and also of 3-and 4-way hybrids.Department of Plant Breeding and Biometry paper No. 690     

Evidence for maternal effect in the inheritance of grain protein in crosses between cultivated and wild tetraploid wheats

Summary Reciprocal crosses were made between cultivated wheat (Triticum turgidum var. durum) and a high-protein line of wild tetraploid wheat (T. turgidum var. dicoccoides). F₁ grains (on maternal spikes) were very similar to the selfed grains on the maternal parent in protein percentage, weight and protein content. These traits were also analyzed in F₃ grains developed on F₂ spikes of segregating populations derived from reciprocal crosses between the same cultivated parent and another high-protein line of var. dicoccoides. No significant differences in the mean values of these traits were found between the reciprocal crosses, indicating no cytoplasmic effect. It has been concluded that these grain characteristics are largely determined by the maternal plant.Recipient of Sir Charles Clore Postdoctoral FellowshipThe Marshall and Edith Korshak Professor of Plant Cytogenetics     

Dominant pleiotropy controls enzymes co-segregating with paraquat resistance in Conyza bonariensis

Summary The genetics of paraquat-resistance in Conyza bonariensis was studied. Reciprocal crosses were prepared between resistant and sensitive individuals. The enzymes of the pathway that detoxifies superoxide to innocuous oxygen species involved in resistance were evaluated in the F₁ and F₂ generations. All F₁ plants were as resistant as the resistant parent, irrespective of parental sex, demonstrating dominance and excluding maternal inheritance. The activities of superoxide-dismutase, ascorbate-peroxidase and glutathione-reductase in the F₁ were constitutively as high as in the resistant parent. Resistance in the F₂ generation was distributed in a 31 ratio (resistant to sensitive). Leaves from F₂ plants were removed for a resistance assay and enzyme immuno-assays of single plants were performed. The high levels of superoxide-dismutase and glutathione-reductase, the two enzymes for which antibodies were available, were similar in resistant individuals to the levels in the resistant parent; the levels were low in the susceptible individuals. These results indicate either a very tight linkage, or more probably, that one dominant nuclear gene controls resistance by pleiotropically controlling the levels of enzymes of the activeoxygen detoxification pathway.     

Inheritance of bipyridyl herbicide resistance in Arctotheca calendula and Hordeum leporinum

The mode of inheritance of resistance to bipyridyl herbicides in bipyridyl-resistant biotypes of Arctotheca calendula and of Hordeum leporinum was investigated. F₁ plants from reciprocal crosses between diquat-resistant and -susceptible plants of A. calendula showed an intermediate response to diquat application that was nuclearly inherited. Treatment of F₂ plants with 100 g ai ha^-1 of diquat or 800 g ai ha^-1 of paraquat killed all homozygous-susceptible plants, caused severe injury to heterozygous plants but only slight or no injury to homozygous-resistant plants. Back crosses of F₁ to susceptible plants exhibited intermediate and susceptible phenotypes. The observed segregation ratios in F₂ and test-cross populations fitted predicted segregation ratios, 1:2:1 (R:I:S) and 1:1 (I:S) respectively, showing that bipyridyl resistance is conferred by a single incompletely-dominant gene. Biotypes of paraquat-resistant and -susceptible H. leporinum were crossed reciprocally. F₁ plants from reciprocal crosses showed an intermediate response to paraquat application. The F₂ progeny showed segregation ratios that fitted the predicted segregation ratio of 1:2:1 (R:I:S) forinheritance of resistance being governed by a single partially-dominant gene.     

REPRODUCTIVE ISOLATION OF TRITICUM BOEOTICUM AND TRITICUM URARTU AND THE ORIGIN OF THE TETRAPLOID WHEATS

The diploid wheats Triticum boeoticum and T. urartu are sympatric with one another throughout the geographic range of the wild tetraploids. Reciprocal crosses between ecogeographic types within each diploid species gave viable seed, but interspecific crosses consistently gave viable seed only when T. boeoticum was the female parent. Apparently urartu cytoplasm in combination with the boeoticum genome resulted in nonviable seed. The endosperm failed to develop normally despite regular endosperm fertilization. The F₁ plants obtained were completely self sterile although they showed regular intergenomic pairing (7II) at meiosis. Presumably the accumulation of cryptic differences between the two closely related genomes under reproductive isolation accounts for this sterility. The same accumulated cryptic differences could largely account for the preferential diploid pairing in the tetrapolid wheats which presumably were derived from such hybrids by chromosome doubling. The behavior of reciprocal crosses between the diploids and tetraploids suggested that T. boeoticum contributed the cytoplasm to both of the wild tetraploid species.     

Genetic control of high stearic acid content in seed oil of two soybean mutants

 Stearic acid is one of the two saturated fatty acids found in soybean [Glycine max (L.) Merr.] oil, with its content in the seed oil of commercial cultivars averaging 4.0%. Two mutants, KK-2 and M25 with two- and six-fold higher stearic acid contents in the seed oil than cv ‘Bay’, were identified after X-ray seed irradiation. Our objective was to determine the genetic control of high stearic acid content in these mutants. Reciprocal crosses were made between each mutant and ‘Bay’, and between the two mutants. No maternal effect for stearic acid content was observed from the analysis of F₁ seeds in any of the crosses. Low stearic acid content in ‘Bay’ was partially dominant to high stearic acid content in KK-2 and M25, and high stearic acid content in KK-2 was partially dominant to high stearic acid content in M25. Cytoplasmic effects were not observed, as demonstrated by the lack of reciprocal cross differences for stearic acid content in our analysis of F₂ seeds from F₁ plants. The stearic acid content in F₂ seeds of KK-2בBay’ and M25בBay’ crosses segregated into three phenotypic classes which satisfactorily fit a 1:2:1 ratio, indicating that high stearic acid content in KK-2 and M25 was controlled by recessive alleles at a single locus. The data for stearic acid content in F₂ seeds of the KK-2×M25 cross satisfactorily fit a 3:9:1:3 phenotypic ratio. The F₂ segregation ratio and the segregation of F₃ seeds from individual F₂ plants indicated that KK-2 and M25 have different alleles at different loci for stearic acid content. The alleles in KK-2 and M25 have been designated as st ₁ and st ₂, respectively. The stearic acid content (>30.0%) found in the st ₁ st ₁ st ₂ st ₂ genotype is the highest known to date in soybean, but it was not possible to develop the line with this genotype because the irregular seeds failed to grow into plants after germination. Therefore, tissue culture methods must be developed to perpetuate this genotype. Received: 28 March 1997 / Accepted: 18 April 1997     

Study on inheritance of resistance to root aphid, Pemphigus bursarius, in lettuce

The inheritance of resistance to lettuce root aphid, Pemphigus bursarius, was studied in lettuce using the Wellesbourne cultivars Avondefiance and Avoncrisp as resistant parents and Borough Wonder and Webb's Wonderful as aphid-susceptible parents. All four cultivars were crossed in all possible combinations including reciprocals and the response to root aphid of plants in the P₁F₁F₂ and BC generations was assessed using apterae of P. bursarius from the lettuce cv. Iceberg. Resistance to attack was clearly inherited and the parents appeared to be homozygous for their resistance or susceptibility. In the F₁ generation, however, in all crosses between resistant and susceptible parents, segregation into susceptible, resistant and some slightly less resistant plants occurred. This and the highly significant differences in segregation between pairs of reciprocal crosses in the F₁ and other generations indicate that the inheritance of resistance to root aphid is controlled by extra-nuclear factors. Modifying genes might also be involved but there appears to be no linkage of root aphid resistance with resistance to downy mildew, for which the Wellesbourne lettuces were bred.     

Inheritance of partial resistance to the leaf aphids Macrosiphum euphorbiae and Uroleucon sonchi in lettuce

The genetics of partial resistance (PR) of lettuce to the leaf aphid species Macrosiphum euphorbiae and Uroleucon sonchi was studied in F₁ and F₂ generations of six crosses between four cultivars. Partial resistance inherited mainly additively. With M. euphorbiae the estimates of broad-sense F₂ heritability were low and non-significant in crosses between parents of the same resistance level (S x S and PR x PR), and high (0.69-0.76) in crosses between parents of different resistance level (PR x S). The level of resistance in lettuce cultivars ‘Charan’ and ‘Marbello’ led to a marked reduction in percentage of plants with colonies of M. euphorbiae in a field experiment. With U. sonchi the highest estimates of F₂ heritability were found in ‘Charan x ‘Avoncrisp’ (0.51) and ‘Charan’ x ‘Chou de Naples' (0.48). In the cross ‘Charan’ x ‘Marbello’ (PR x PR) no significant segregation for resistance to M. euphorbiae was found, indicating that these cultivars may have the same genetic constitution for resistance to M. euphorbiae.‘Charan’ has additional genes for resistance to U. sonchi, that are not, or only weakly linked to the gene(s) for resistance to M. euphorbiae. The heritability estimates for the partial resistance to M. euphorbiae and U. sonchi indicate that it is possible to effectively select for these traits in plant breeding programmes.     

Genetic studies of self-fertility in rye (Secale cereale L.). 1. The identification of genotypes of self-fertile lines for the Sf alleles of self-incompatibility genes

Segregation for self-fertility has been studied in progenies from the crosses of self-sterile (SS) plants with interline hybrids obtained by a diallel scheme of pollinations between seven self-fertile (SF) lines (nos. 2–8) and with F₁ (SS plant x SF line) hybrids. All the offspring families from the SS plant x F₁ (SS plant x SF line) crosses demonstrated a 1SF1SS segregation. The crosses of SS plants with some interline hybrids gave only self-fertile plants, whereas the crosses with other interline hybrids gave a segregation of 3SF:1SS expected in the case of digenic segregation. The data obtained permitted us to identify three different S loci (S1, S2, S5) and to estimate the genotypes of self-fertile lines for their Sf alleles: lines 5, 6, 7 and 8 are S1f/S1f S2n/S2n S5m/S5m, line 4 is S1n/S1n S2f/S2f S5m/S5m, and lines 2 and 3 are S1n/S1n S2m/S2m S5f/S5f(Sn, Sm designate active alleles of the incompatibility genes). The identification of the particular S gene which is presented by the Sf allele in each line has been made on the basis of our data concerning the linkage of the Sf mutation with isozyme markers of particular rye chromosomes, which is reported in an accompanying paper.