F2 Seeds Research Articles

VARIABILITY AND SELECTION IN AN INTERSPECIFIC HYBRID POPULATION OF PACHYRRHIZUS EROSUS X P. AHIPA (YAM BEAN)

F3 seeds from a cross of P. erosus (indeterminate, daylength sensitive) X P. ahipa (determinate, daylength insensitive) were received from M. Sorensen of the Royal Veterinary and Agricultural University in Copenhagen, Denmark and sown in Hawaii in April, 1989 to increase the seed. The F4 seed were planted in March, 1990 and in October, 1990 (the normal time). All F4 progeny included both bush and vine plants in the summer planting, with more bush plants in the progeny of F3 bushes than vines. Likewise, the progeny of earlier-flowering F3 plants had a higher percentage of plants in flower in June than progeny of later-flowering ones. Root sizes and shapes were variable. The F4 progenies of the lines with the highest percentage of bushes and early-flowering plants were regrown in the summer of 1991 and selected for summer-flowering bush plants with acceptable root size. The selections were then grown in the winter of 1991 to test for performance during the normal growing season.

Genetic difference in somatic embryogenesis from seeds in melon (Cucumis melo L.)

Significant differences in somatic embryogenesis from melon seeds were observed among 18 cultivars; especially, cultivars ‘Earl's Favorite’ and ‘Barnett’ which produced a large number of somatic embryos. F1 seeds were obtained by reciprocal crosses between cultivars. Some lines produced a large number of somatic embryos whereas others showed no or poor embryogenic response. Most of the F1 seeds formed somatic embryos. The frequency of somatic embryogenesis decreased as compared to the parents with the highest potential. Transfer of the frequency of somatic embryogenesis from superior responding cultivars to inferior cultivars was proved. It was difficult to determine the mode of inheritance of somatic embryogenesis because there was a large variation in the range of somatic embryogenesis from F2 seeds, and cytoplasmic effect was recognized in certain combinations.

Parent‐Offspring Regression Estimates of Heritability for Salt Tolerance during Germination in Tomato

Salinity impositions can markedly delay and decrease germination rates of tomato (Lycopersicon esculentum Mill.) seed. Wide phenotypic variability in plant growth and germination responses to salinity stress has been reported, but scant documentation concerning genotypic variation for salt responsiveness has restricted breeding efforts. This study evaluated the heritability of germination performance under salinity stress by parent‐offspring regression. Germination distribution data were collected for Fz and F3 seeds derived from a cross between a saltsensitive (UCT5) and a salt‐tolerant (PI 174263) cultivar under moderately high salinity levels (150 mM synthetic sea salt). Individuals germinating at different response time intervals were recovered and advanced to produce F3 and F4 progeny seeds. Progeny families were evaluated for mean times to selected germination quantiles of 25, 50, and 75% under salt stress and the family means were regressed on the individual parental values. Heritability estimates for the F2:3 regression at the selected quantiles were 0.78, 0.76, and 0.58, respectively. These results were comparable with the F3:4 regression estimates of 0.65, 0.73, and 0.58, respectively. The similarity of the estimates obtained in both parent‐offspring regressions suggests the absence of significant dominance genetic effects and when considered with the moderately high heritabilities estimated (r = 0.58‐0.78), reasonably rapid response to selection in early segregating generations would be expected for this important seed trait in tomato.

CONSTANCY OF POPULATION PARAMETERS FOR LIFE-HISTORY AND FLORAL TRAITS IN RAPHANUS SATIVUS L. II. EFFECTS OF PLANTING DENSITY ON PHENOTYPE AND HERITABILITY ESTIMATES.

To determine the effect of growing conditions on population parameters in wild radish, (Raphanus sativus L.: Brassicaceae), we replicated maternal and paternal half-sib families of seed across three planting densities in an experimental garden. A nested breeding design performed in the greenhouse produced 1,800 F1 seeds sown in the garden. We recorded survivorship, measured phenotypic correlations among and estimated narrow-sense and broad-sense heritabilities (h2 ) of: days to germination, days to flowering, petal area, ovule number/flower, pollen production/flower, and modal pollen grain volume. Survivorship declined with increasing density, but the relative abundances of surviving families did not differ significantly among densities. Seeds in high-density plots germinated significantly faster than seeds sown in medium- or low-density plots, but they flowered significantly later. Plants in high-density plots had fewer ovules per flower than those in the other treatments. Petal area and pollen characters did not differ significantly among densities. Densities differed with respect to the number and sign of significant phenotypic correlations. Analyses of variance were conducted to detect additive genetic variance (Va ) of each trait in each density. At low density, there were significant paternal effects on flowering time and modal pollen grain volume; in medium-density plots, germination time, flowering time and ovule number exhibited significant paternal effects; in high-density plots, only pollen grain volume differed among paternal sibships. The ability to detect maternal effects on progeny phenotype also depended on density. Narrow-sense h2 estimates differed markedly among density treatments for germination time, flowering time, ovule number and pollen grain volume. Maternal, paternal and error variance components were estimated for each trait and density to examine the sources of variation in narrow-sense h2 across densities. Variance components did not change consistently across densities; each trait behaved differently. To provide qualitative estimates of genetic correlations between characters, correlation coefficients were estimated using paternal family means; these correlations also differed among densities. These results demonstrate that: a) planting density influences the magnitude of maternal and paternal effects on progeny phenotype, and of h2 estimates, b) traits differ with respect to the density in which heritability is greatest, c) density affects the variance components that comprise heritability, but each trait behaves differently, and d) the response to selection on any target trait should result in different correlated responses of other traits, depending on density.

Heritability, Heterosis, and Maternal Effects of Alpha‐Amylase Activity in Barley

Alpha‐amylase activity is an important quality factor in malting barley (Hordeum vulgare L.), yet its inheritance is not well understood. Research was undertaken to determine the inheritance and to examine maternal and heterotic effects of α‐amylase activity. The F1 and F2 seeds from reciprocal crosses among barley cultivars grown in the greenhouse were evaluated for α‐amylase activity. Heritability of α‐amylase activity was estimated by measuring activities of seed from field growouts of parents and progeny. The Ceralpha α‐amylase assay method, coupled with a modified malting procedure, was used to determine α‐amylase activity levels of all seed samples in this study. Alpha‐amylase activities of F1 seeds from reciprocal crosses were significantly different in two of three crosses. Activities of F2 seeds from reciprocal crosses did not differ, indicating that the reciprocal differences in the F1 were not cytoplasmicin origin but probably due to gene dosage. Average heterosis of α‐amylase activity of the F1's was 85% over the midparent and 47% over the high parent. In the F2 generation, average percent heterosis over the midparent was 35%. Heritability of α‐amylase activity on an F2 plant basis ranged from 0.37 to 0.65, while on an F5 line basis it ranged from 0.39 to 0.74. Average gain from selection for α‐amylase activity in the F2 and F5 generations was 5.4 and 9.1 Ug −1, respectively. Results indicate that selection for α‐amylase activity in populations of medium to wide genetic diversity should be successful in both early and advanced generations.

Genetic and Linkage Analysis of Aconitate Hydratase Variants in Soybean

Genetic markers and chromosome linkage maps are useful in genetic research and plant breeding. Soybean [Glycine max (L.) Merr.], plants were grown in the greenhouse and field to obtain Ft, F2, and F3 seeds, and starch gel electrophoresis was employed to determine inheritance of several aconitate hydratase isozyme variants and the relative position of the Aco3 locus in soybean Linkage Group 1. Genetic data show that the Aco1 null variant (acol‐n) is allelic to Acol‐a, the Aco2‐c variant is allelic to Aco2‐a, and the Aco4‐d variant is allelic to Aco4‐c. The Aco5 locus has three alleles Aco5‐a, Aco5‐b, and aco5‐n. Recombination values were 12.4 ± 0.8% between the Aco3 and Spl (Am3), 33.6 ± 3.7% between Aco3 and yl2, 39.2 ± 2.1% between Aco3 and t, 13.2 ± 1.2% between Spl and y12, and 29.6 ± 1.3% between Spl and t. The gene order of these markers was thus determined as Aco3‐Spl‐yl2‐t. Based on these five aconitate hydratase isozymes, genetic variation was calculated for both wild and cultivated soybean. No significant differences in the level of genetic variation [gene diversity (heterozygosity) and number of alleles per locus] between wild and cultivated soybean were observed. The values for gene diversity and number of alleles per locus in soybean are comparable to those observed in other autogamous annual plant species.

Effect of Absence of Seed .ALPHA.-Amylase Inhibitor on the Growth Inhibitory Activity to Azuki Bean Weevil(Callosobruchus chinensis)in Common Bean(Phaseolus vulgaris L.).

Individual seeds of 212 common bean cultivars were analyzed by Ouchterlony immunodiffusion method using the antiserum raised against common bean α-amylase inhibitor (CBAI). Two cultivars, Ofuku-5 and Ofuku-8, gave no reaction with the anti-CBAI serum and no inhibitory activity against porcine pancreatic α-amylase. Furthermore, these CBAI-lacking cultivars contained no lectin.'Analysis of F2 seeds from the cross between Ofuku-5 and Taishou-kintoki (CBAI-containing) indicated that the absence of CBAI was recessive to the presence of CBAI and tightly linked to the absence of lectin. In a previous report, we showed that CBAI strongly inhibited the larval growth of Callosobruchus chinensis. Thus, effects of the absence of CBAI on the larval growth of C. chinensis were examined using artificial beans containing seed components of the two CBAI-lacking cultivars and two CABIcontaining cultivars (Taishou-kintoki and Ofuku-1). The flour of the CBAI-lacking cultivars showed weak inhibitory activity on the larval growth compared with that of the CBAI-containing cultivars, although the larvae could not grow in the intact seeds of the CBAI-lacklng cultivars. The role of lectin, which was also absent In the seeds of Ofuku-5 and Ofuku-8, has been implicated with resistance to insects, especially bean weevils. CBAI and the lectin in the seeds of the CBAI-containing cultivars were separated well by extraction with 20mM sodium phosphate buffer solution and subsequent ammonium sulfate fractionation. The feeding tests using the protein fractions separated from the CBAI-lacking cultivars and the CBAI-containing cultivars demonstrated that the absence of CBAI is considerably responsible for the lowering of the growth inhibitory activity of the flour of CBAI-lacking cultivars.

Inheritance of Reduced Palmitic Acid Content in Seed Oil of Soybean

Reduction of the palmitic acid content of soybean [Glycine max (L.) Merr.] would lower the total saturated fatty acid content of the seed oil. A mutant line, A1937NMU‐173, with ≈30 g kg‐1 less palmitic acid than commercial soybean cultivars was obtained by the treatment of seeds of the cultivar A1937 with N‐nitroso‐N‐methyl‐urea (NMU). To determine the genetic control of the reduced palmitic acid, A1937NMU‐173 was crossed reciprocally to C1726, a line with the fap1 allele that lowers the palmitic acid content. No maternal effect for palmitic acid was observed from the analysis of F1 seeds from reciprocal crosses. The segregation observed from the analysis of individual F2 seeds for palmitic acid content satisfactorily fit a ratio of 9 greater than either parent: 2 within the range of the parents: 5 less tahn either parent. The F2 segregation ratio and the segregation of F3 seeds from F2 plants indicated that A1937NMU‐173 and C1726 have different alleles at two independent loci. The allele in A1937NMU‐137 has temporarily been designed fapx. the genotype fap1 fap1 fapx fapx has ≈ g kg‐1 of palmitic acid, which is the lowest content known in soybean.

Interspecific hybrids and possible phylogenetic relations in grain amaranths

Phylogenetic relations among the three species in grain amaranth need investigation to provide information for breeding experiments germplasm conservation efforts, and decision on evolutionary patterns in the grain types. Hybrid development from crosses between species was studied to find out genetic relationship between them. Interspecific crosses were made among Amaranthus hypochondriacus, A. caudatus and A. cruentus in the glasshouse. The F1 plants were relatively easy to obtain but had low pollen fertility (10.3–15.1%) and low seed set. A few of these hybrids did not produce seeds. Only a few F1 seeds obtained in crosses between A. cruentus and A. caudatus. All the F1 plants from these crosses died at the seedling stage. Crosses between A. cruentus and A. hypochondriacus produced few seeds. Most of the F1 plants obtained from the seeds died at the seedling stage with only four plants growing to maturity but were sterile. Based on hybrid development, it was suggested that A. hypochondriacus and A. caudatus were genetically closer than the other two combinations of species studied. A. cruentus seemed to be genetically closer to A. hypochondriacus than it was to A. caudatus.

A rapid and economical method for hybrid purity testing of tomato (Lycopersicon esculentum L.) F1 hybrids using ultrathin‐layer isoelectric focusing of alcohol dehydrogenase variants from seeds

In the cultivated tomato (Lycopersicon esculentum L.), two electrophoretic variants of the enzyme alcohol dehydrogenase (ADH) encoded by the alleles Adh-1+ and Adh-1(1) are found. A rapid and economic method for testing the hybrid purity of tomato F1 seeds, based on the expected presence of Adh-1 alleles, was developed. The method is based on the analysis of the ADH variants by ultrathin-layer isoelectric focusing, pH range 3-10, of crude extracts from imbibed seeds, followed by enzyme activity staining. The isoelectric points (pI's) of the ADH variants were estimated to be 5.5 and 5.7 for Adh-1+ and Adh-1(1), respectively. Using the procedure described and a newly developed sample applicator strip, it is possible for one person to routinely analyze 1152 seeds per day using only a single electrophoresis unit. An investigation of a large number of inbred lines, both experimental and commercial hybrids, together with open-pollinated varieties, showed the potential of the method. Among F1 hybrids, a higher frequency of the Adh-1(1) allele was found than among open pollinated varieties, suggesting that F1 hybrid breeding has resulted in a higher frequency of Adh-1(1) alleles by selection of linked genes.

Inheritance of Striga Resistance in Cowpea Genotype B301

The parasitic weed, Striga gesnerioides (Willd.) Vatke, is a major constraint in cowpea [Vigna unguiculata (L.) Walp.] production semi‐arid regions of sub‐Sahara Africa. Several sources of resistance have been identified. Of these, B301 has shown complete resistance to Striga across several countries. This study was undertaken to elucidate the genetics of Striga resistance in this line so that it can be effectively used in breeding programs. It was crossed to a susceptible cultivar, IT84S‐2246‐4. Parental, F1, F2, and backcross seeds were screened for Striga infection using pot‐culture technique. Roots of each plant were washed free of soil and examined for Striga attachment. All 52 plants of B301 were completely free from Striga, whereas all 50 plants of IT84S‐2246‐4 were infected. All the 13 F1 plants and 47 backcross F1 plants involving B301 were also completely free. The backcross Ft plants involving IT84S‐2246‐4 segregated into.15 resistant: 14 susceptible ratio, whereas the F: plants segregated into 142 resistant and 47 susceptible, giving a close fit to 1:1 and 3:1 ratios, respectively. These data indicate a monogenic dominant inheritance for resistance to Striga in cowpea for which the gene symbol Rsg (resistance to S. gesnerioides) is assigned.

Mutants for rice storage proteins. IV. Maternally inherited mutants for storage proteins of protein bodies in the starchy endosperm

Maternal inheritance, a phenomenon extremely rare in plants, was observed in two mutants for rice storage protein in the starchy endosperm. When these mutants, 10/13a-L and 10/16-H, were crossed reciprocally with their original variety, Kinmaze, the F1 seeds in all crosses showed the same character as the maternal parent. The F2 seeds of the reciprocal crosses between Kinmaze and 10/13a-L were also of normal type, but those between Kinmaze and 10/16-H showed 10/16-H type. In 10/13a-L, the segregation ratio of F2 plants observed in F3 seeds showed a good fit to the expected 3:1 ratio, and in 10/16-H, the segregation ratio of F2 plants observed in F3 seeds showed a good fit to the expected 1:3 ratio. From the results of F1, F2 and F3 seeds, it was concluded that the mutants were expressed according to the genetic behaviour of material inheritance governed by plant genotype, and that 10/13a-L and 10/16-H were controlled by a single recessive and dominant gene, respectively. SDS-PAGE analysis indicated that both mutant genes were regulatory genes for the storage proteins. Based on the results of allelism tests, the genes for 10/13a-L and 10/16-H were designated as esp-3 and Esp-4, respectively. Since esp-1, the gene controlling the 13b-L, a mutant of rice storage protein, produces loss of the effect of maternal inheritance of esp-3, it is assumed that esp-1 is epistatic to esp-3.

Inheritance of "group A saponin" in soybean seed.

Two kinds of “group A saponin,” Aa and Ab, are present as the main constituent in soybean seed. The saponin composition and content in F1 and F2 seeds derived from the cross parents of Aa and Ab types were analyzed. The “group A saponin” was of Aa–Ab type in all the F1 seeds, and the ratio of Aa type : Aa–Ab type : Ab type was 1:2:1 in the F2 seeds. From these results, it appears that Aa and Ab were controlled by codominant allelic alternatives at a single locus. An investigation of the saponin composition of the seed hypocotyls of 18 wild lines revealed some lines in which “group A saponin” was absent.

Alcohol dehydrogenase zymogram, its inheritance and anaerobic germinability of seeds of Echinochloa weeds.

Seed polymorphism of Echinochloa weeds in alcohol dehydrogenase (ADH), which has a critical function for the paddy weeds to germinate under flooding, was studied in the 196 individual accessions of the paddy and upland weeds collected in natural populations. The ADH zymograms detected in seeds were highly polymorphic and classified into five types; A3, A1A2A3, A1A3A5, A3A4A5 and A1A2A3A4A5. The majority of each species and varieties had a specific zymogram; E. oryzicoloa, A1A2A3; E. crus-gall var. formosensis, A1A2A3A4A5; E. crus-gell var. praticoloa. A3. E. crus-galli var. crus-galli having a widespread habitat had somewhat varied zymograms. The F1 seeds obtained from reciprocal crosses between E. crus-galli var. formosensis (A1A2A3A4A5, a paddy weed) and var. praticola (A3, an upland weed) had A1A2A3A4A5, and the observed segregation ratios of the F2 seeds derived by selfing F1 plants fitted to the two gene segregation mode of 9:3:3:1 for A1A2A3A4A5:A1A2A3:A3A4A5:A3. No distinct relationship was found between anaerobic seed germinability and ADH zymograrns of Echinochloa weeds collected in the natural populations. None of the accessions with A3, however, showed anaerobic germinability whereas the others with either A1A2A3 or A1A2A3A4A5 did in E. crus-galli var. praticola.

Inheritance of Fatty Acid Content in Peanut Oil1

Abstract The stability or shelf-life of peanut (Arachis hypogaea L.) oil is related to the fatty acid content of the oil, with the major factor being the ratio of oleic (C18:1) to linoleic (C18:2) acid (O/L ratio). To obtain information needed for development of cultivars with improved oil quality, eight parents representing a range in oleic and linoleic content were crossed in diallel. Individual F1 seeds (F1 embryos) from the greenhouse and F2 bulk seed from the 56 crosses grown in the field were analyzed to determine levels of the eight major fatty acids. General combining ability (GCA) was consistently more important than specific combining ability (SCA) in both generations, suggesting that additive effects are important in the inheritance of fatty acid composition. Maternal effects were significant in the F1 but dissipated in the F2; thus the differences in the environment provided by the maternal parent was more critical to oil composition than heritable extranuclear factors. Reciprocal effects were significant in both generations suggesting an interaction between nuclear and extranuclear factors. Correlations between GCA effects and self means for O/L ratio were nonsignificant. Since no significant correlations were found between percent oil and any of the fatty acids or related variables, selection for improved fatty acid composition should not affect the oil content of seed. Of the lines studied, NC 7, NC-Fla 14, and 73–30 should be used as parents in a breeding program for oil quality.

Inheritance of two endosperm protein loci in rice (Oryza sativa L.)

Previous studies indicated two types of phenotypic protein markers as two minor bands of SDS-PAGE for rice storage protein. A variant derived from a Pakistani variety, Dular, was found to show a mobility variant with Band 11, a relatively faster-moving band as compared to Band 10, while most of the other cultivated rices exhibited Band 10 at a molecular weight of around 100-110 K. Band 11 was also observed in several wild rice species. How this variant occurred is not known. Another marker is characterized by the presence of either Band 56 (slower-migrating band) or Band 57 (faster-migrating band) in most cultivars at a molecular weight of about 28-27 K. Most indica varieties developed in Taiwan have Band 57 and japonica varieties have Band 56. Genetic analysis of F1, F2 and F3 seeds from interstrain crosses indicated that Band 10 versus Band 11 and Band 56 versus Band 57 are due to codominant alleles at two loci. Tests of independent inheritance between these two loci (Band 10/11 versus Band 56/57) indicated that there is no linkage between them. Both of these two protein loci encode for endosperm proteins and mostly belong to the minor polypeptide subunits of the glutelin fraction of rice seed proteins. Studies on reciprocal crosses indicate dosage effects as exhibited in band patterns. Variations in band intensity were frequently observed when the maternal genotype was different.

Analysis of phylogenetic relations of durum, carthlicum and common wheats by means of comparison of alleles of gliadin-coding loci

Polymorphism and inheritance of wheat storage protein, gliadin, of durum (macaroni) and carthlicum wheats have been studied. Analysis of gliadin in 78 cultivars and in F2 seeds of intercultivar crosses of durum wheat revealed three different chromosome 1A-encoded blocks of components similar to those found in common wheat (GLD1A2, GLD1A18, GLD1A19). Most of the durum cultivars studied had these three blocks; GLD1A2 was also frequent in common wheat. In contrast, all chromosome 1B-encoded blocks of durum clearly differed in component composition from those found in common wheat. Therefore, durum could not be an ancestor or a derivate of recent bread wheat. Analysis of gliadin in the collection of carthlicum wheat (14 accessions) revealed several suspected chromosome 1A, 1B, and 6A-controlled blocks, some of which were similar to those in common wheat, while others were different. Therefore, carthlicum is likely to be an ancestor or a derivate of some forms of bread wheat. There were also chromosome 1A and 6A-, but not 1B-encoded blocks which were identical in durum and carthlicum wheats. The results confirm that all three wheats share the same genome A, but emphasize the heterogeneity of genotypes among donors of this genome. Discovery of identical blocks in tetraploids and hexaploids indicates polyphyletic [from different genotypes of donor (s)] origin of these wheats.

Genetic analysis of the high oleic acid content in cultivated sunflower (Helianthus annuus L.)

Sunflower lines breeding true for very high oleic acid content in their oil (average levels higher than 85%) were crossed with standard sunflower lines with mean oleic acid levels of 30%. Analysis of the oil of F1 seeds indicated dominance for high oleic levels and control of the genotype of the embryo. Segregating generations were obtained selfing heterozygous high oleic BCnF1 plants from several generations of a backcrossing program to incorporate the high oleic character to standard inbred lines and testcrossing these plants to low oleic material. Analysis of F2 and testcrossed seeds showed three kind of segregations, in both F2 and testcrossed populations, with different proportions of low, intermediate and high oleic types. Genetic analysis of these data supported the hypothesis, that the high oleic character is controlled by three dominant complementary genes OL1, OL2 and OL3. Additional data showing F1 seeds with intermediate oleic content and segregations for high oleic in progenies of intermediate types, suggest the presence of major factors modifying high oleic acid content.

Transmission of an alien telocentric addition chromosome in common wheat that confers blue seed color

Phenotypic markers of chromosomes are useful for determining chromosome behavior in cytogenetic studies. Transmission of an alien, telocentric addition from Agropyron tricophorum (Link) Richt. that confers purple aleurone pigment and blue seed color was evaluated in common wheat (Triticum aestivum L.). Twenty-five of 2570 seeds from bagged heads of eight ditelocentric-addition sister plants were almost white rather than blue. Seven of these 25 seeds and 4 of 336 blue seeds segregated 41.4%:58.6% blue:white. Meiotic analyses showed that all plants grown from these 11 seeds were spontaneously produced monotelocentric additions. Transmission of the alien telocentric chromosome through the egg and the pollen was estimated to be 19.5 and 14.3%, respectively, based on BC1F1 seed color. About 28% of F2 and F3 seeds were blue; of these 7.4% were ditelocentric additions. The frequency of blue seed in F2 progeny from spontaneous monotelocentric additions (41.4%) was significantly greater than that of monotelocentric additions from controlled crosses (28%). Penetrance of the blue seed color gene(s) associated with the alien telocentric chromosome was good. Misclassification of seed color for 1595 BC1F1 seeds was less than 3% based on BC1F2 progeny.Key words: Agropyron tricophorum.

Monogenic resistance in tomato to Fusarium oxysporum f. sp. lycopersici race 3

Resistance to fusarium wilt, incited by Fusarium oxysporum (Schlecht.) f. sp. lycopersici (Sacc.) Snyder & Hansen race 3 in tomato (Lycopersicon esculentum Mill.) was discovered in LA 716, a L. pennellii accession. A resistant BC1F3 breeding line, E427, was developed from LA 716. E427 was crossed with the susceptible cv. Suncoast and F1, BCP1, BCP2 (to Fla 7155, a susceptible parent) F2, F3, and BCP2S1 seeds were obtained. Segregation for resistance following root dip inoculation over three experiments indicated a single dominant gene controlled resistance. Five of the 12 BCP1S1's segregated more susceptible plants, whereas one of the 12 segregated more resistant plants than expected (P<0.05). Three of 23 F3 lines segregated more susceptible plants than expected while 1 of the 23 had more resistant plants than expected (P<0.05). Segregation in all other lines fit expected ratios. Five of the 23 F3's were homozygous resistant which was an acceptable fit to expectations (P=0.1−0.5). The gene symbol I 3 is proposed for resistance to race 3 of the wilt pathogen. Deviations from expected ratios in data reported here and for other breeding lines indicate an effect of modifier genes and/or incomplete penetrance. Plant age at inoculation and seed dormancy did not affect results.