Inbreeding depression in garden and glasshouse chrysanthemums: germination and survivorship

Summary Sixty-six chrysanthemum (Dendranthema grandiflora) inbred selections, noninbred cultivars and hybrids, and D. makinoi were the base populations from which up to three generations of inbreds were obtained using multiple plant descent. Each parent possessed pseudo-self compatibility (PSC), which allowed seed set following self pollination. Rapid-generation cycling (laboratory seed ripening to heart stage and subsequent embryo rescue) reduced generation time and minimized confounding maternal with zygotic inbreeding depression during post heart-stage seed development. Selection criteria were male/female fertility and PSC. Two stages of the life cycle were chosen to evaluate inbreeding depression: germination (seed development to germination) and survivorship (fertile individuals at anthesis). PSC was environmentally interactive and genotype dependent, causing variable levels of self seed set between and within populations and generations. By the end of the second generation, families from all noninbred cultivars, D. makinoi, and one F₁ hybrid were eliminated from the experiment due to self incompatibility and/or inbreeding depression. Post-germination inbreeding depression was severe in several advanced inbreds. Inbred progeny of most F₁ or F₂ hybrids expressed less or equal amounts of inbreeding depression compared to advanced inbreds. Linear regression coefficients for either germination or survivorship on percent homozygosity were negative. Correlation coefficients between percent germination and survivorship (as a percent of seed set) were highly significant for Minnesota inbreds (r=0.67, P0.002) and hybrids (r=0.67, P0.006). The correlation coefficient was higher when percent germination and survivorship (as a percent of germinated seedlings) were compared (r=0.95, P0.001).Abbreviations F Fisher's Coefficient of Inbreeding - IBD Inbreeding Depression - PSC Pseudo-self Compatibility - RGC Rapid Generation Cycle - SI Self Incompatibility     

Genetic analysis of inbred lines and their crosses for resistance to head blight (Fusarium culmorum,F. graminearum) in winter rye

Summary For genetic analysis of head blight in winter rye (Secale cereale) caused by Fusarium culmorum, six homozygous inbred lines from the Petkus gene pool were crossed in all combinations to obtain 15 diallel F₁ crosses and the corresponding 15 F₂ crosses. These materials and 10 additional inbreds were artificially inoculated in a 2-year field experiment. The inbreds were also tested with F. graminearum in a separate sub-experiment.Single disease rating, average disease rating, and yield components (grain-weight per spike, 1000-grain weight, kernel number per spike) relative to the non-inoculated treatment were significantly affected by Fusarium head blight in all material groups. The relative grain weight per spike ranged from 26% to 88%. Significant genotypic and genotype x year interaction variances were found throughout. Heritabilities were highest for homogeneous inbreds (h²=0.6–0.8) and lowest for heterogeneous F₂ crosses (h²=0.4–0.6). Disease rating and relative grain-weight per spike were highly correlated for the inbreds and F₂ crosses (r0.7, P0.01), but lower for the F₁ crosses (r0.6, P0.05). Inter-annual correlation coefficients for disease ratings and relative grain-weight per spike ranged from r0.7 (inbreds) to r0.5 (F₂ crosses). The diallel analysis showed significant GCA effects only for relative 1000-grain weight in 1990, but significant SCA and SCAx year interaction variances for most traits. The resistances of 16 inbreds to F. culmorum and F. graminearum were tightly associated for all traits (r=0.96–0.97, P0.01).In conclusion, only slow progress can be expected from selecting for Fusarium head blight resistance in rye due to the limited amount of additive genetic variance and the great improtance of environmental factors.     

Effect of selection for pseudo-self compatibility in advanced inbred generations of Nemesia strumosa Benth.

Summary Highly pseudo-self compatible (PSC) Nemesia strumosa plants were selfed and intercrossed to produce progenies of the F₅ through F₇ generations. Though high PSC progenies were obtained, none were truebreeding. Progenies from crossing inbred high PSC plants to low PSC plants consisted of either mostly low PSC plants or both low and intermediate plants. A backcross to the high PSC parent of a progeny from a low times high cross produced a family with a PSC frequency distribution skewed toward low PSC but with a few high PSC plants. These data may be explained if PSC genes at some or most loci are incompletely dominant to non-PSC genes and threshold numbers of PSC genes are required for PSC expression and for 100% PSC plants. Dominance may also occur at some loci. Although only a small number of genes may be required to produce a high PSC plant, the total number of PSC genes may be large.Scientific Journal Series Paper No. 11,676 of the Minnesota Agricultural Experiment Station.     

Genetics of nitrate content in lettuce

Summary Adverse effects on human health makes the high nitrate content frequently found in lettuce (Lactuca sativa L.) grown under low light conditions an undesirable trait. Efforts have been made to breed cultivars with a reduced capacity for nitrate accumulation. In this study components of variance for nitrate content were estimated in F₂ and F₃ generations of ten lettuce crosses. Additive genotypic variances (A) were estimated from F₃ variance components and from the covariance between F₂ plants and corresponding F₃ lines. Estimates of wide sense heritability of the F₂ from crosses between a high nitrate genotype and four low nitrate genotypes ranged from 0.44 to 0.74 and the estimates for A ranged from 0.25 to 0.40 g·l^-1. Estimated wide sense heritabilities of F₂'s from six crosses involving two low nitrate parents ranged from 0.15 to 0.52. The parents of four of the low nitrate crosses showed relatively large effects of genotype x environment (GE) interaction in successive experiments: the nitrate content of the parents reacted differently to environmental changes between experiments. Estimates of A for crosses between low nitrate genotypes without large effects of GE interaction ranged from 0 to 0.19 g·l^-1. The estimated probability of selecting transgressive low nitrate lines in the progeny of a cross between a high and a low nitrate genotype was low (P=0.002–0.039), indicating that large populations should be evaluated to combine the positive traits of modern high nitrate cultivars with low nitrate content from genotypes not adapted to modern cropping practices. In the progenies from crosses between two low nitrate genotypes without important GE effects, only low estimates of the probability of obtaining transgressive low nitrate lines were obtained (P=0.04–0.06). With the growth conditions used in this study, the probability of selecting lines with a nitrate content compatible under all winter conditions with the proposed future maximum permissible level of 2.5 g nitrate per kg fresh matter is low. Therefore the solution of this problem should be found in a combination of low nitrate cultivars and cultural measures that reduce the nitrate content of the crop.     

A rapid procedure for screening the resistance of bean cultivars (Phaseolus vulgaris L.) to Botrytis cinerea and Sclerotinia sclerotiorum

Summary A method to inoculate detached bean leaves with Botrytis cinerea or Sclerotinia sclerotiorum without using a carbon-nitrogen source is described. Leaves were incubated in plastic trays that were covered with transparent plastic bags to maintain air humidity above 95%. Spores of either fungus inoculated in water alone were generally unable to cause infection. Additions of KH₂PO₄ (62.5 mM) or of mixtures of inorganic phosphate and glucose (1.1 or 5.5 mM) to the inoculum stimulated fungal pathogenicity. Also spore concentration (2×10⁵ or 2× 10⁶ spores ml^–1) influenced the ability to produce lesions. At 2× 10⁶ spores ml^–1 both fungi were able to infect primary bean leaves when inoculated in an inorganic phosphate solution. These conditions were used for a preliminary screening for resistance of 15 bean cultivars to both fungi. Only partial resistance to the pathogens was found. Since the procedure is simple and does not require blooming plants, it can be rapidly adopted in screening and breeding programs.Abbreviations Pi inorganic phosphate     

Inheritance of tolerance to leaf iron deficiency chlorosis in tomato

By using two tomato genotypes, 227/1 (Fe chlorosis susceptible) and Roza (Fe chlorosis tolerant), and their reciprocal F₁, F₂ and BC₁ generations, the inheritance of tolerance to leaf Fe deficiency chlorosis of Roza was studied. Plants were grown in a nutrient solution and subjected to 2.0 × 10^–6 M Fe EDDHA and 10 mM NaHCO₃ to induce Fe deficiency stress by stabilization of pH to 7.8–8.2. A rating scale of 1–3 for chlorophyll was used and both monogenic and polygenic inheritance hypotheses were tested. Better responses to Fe deficiency, as measured by SPAD meter values, were obtained from the cross Roza × 227/1 than from the reciprocal cross. Data from F₂ and BC₁ suggest Fe chlorosis tolerance of Roza is to be controlled by polygenic loci with a relatively high additive effect.     

An artificial trispecific Eucalyptus hybrid: (E. camaldulensis Dehn. × E. tereticornis Sm.) × E. grandis Hill ex Maiden

Summary Starting with a promising E. camaldulensis × E. tereticornis hybrid FRI-5, a (E. camaldulensis × E. tereticornis) × E. grandis trispecific hybrid FRI-13 was synthesized. The trispecific hybrids were generally intermediate between the parents in most juvenile traits but in some they strongly resembled E. grandis, thus proving their hybrid nature. About a fifth of the trispecific hybrid progeny displayed a stunted grass phase during early post-cotyledonary development, but later changed into nearly normal types. The potential practical value of multiple species crosses in Eucalyptus breeding and improvement is indicated.     

Inter-and intraracial hybridization and selection for seed yield in early generations of common bean,Phaseolus vulgaris L.

Summary Five parents from each of four race groups of common bean (Phaseolus vulgaris L.) were hybridized to produce five crosses within each group. Also, five crosses were made for each of the six possible combinations among four groups. Parents, F₁ and F₂, and parents, F₂ and F₃ were evaluated for seed yield in 1990 and 1991, respecitively, at two locations in Colombia.Yield of parents belonging to Middle American races and crosses among them was higher than that of races of Andean origin. Positive correlations were found among the mid-parent value, F₁, F₂ and F₃. Also, the mid-parent value predicted the mean seed yield of all possible lines that could be derived from the F-generation in 42 out of 47 crosses. Four crosses, all between common bean races of Andean and Middle American origin, indicated a possible loss of favorable epistatic parental alleles. On average, mean yield of interracial F₁ hybrids was higher than that of intraracial ones.Positive heteroris (26.4%–123.8%) over the mid-parent in 31 crosses, and F₁s yielding higher (23.7%–91.8%) than the high parent in 20 crosses and yielding higher (22.1%–53.2%) than the highest control among all parents (MAM 13) in 12 crosses, were found. Heritability, estimated by the parent-offspring regression, ranged from 0.42± 0.07 to 0.49±0.04. Expected and realized gains from selection (at 20% selection pressure) ranged from 10.3% to 21.0% over the mean of F₁ hybrids and F₂ and F₃ population bulks.     

Bolting resistant breeding of Chinese cabbage. 1. Flower induction of late bolting variety without chilling treatment

Summary When a local slow bolting variety Osaka Shirona Bansei (Brassica rapa L. ssp. pekinensis, syn. B. campestris L. ssp. pekinensis) was grown in a phytotron (25°C, 16 hours day length without chilling treatment), one third of the plants bolted and flowered. In order to clarify the different flowering responses in the variety, a progeny line (FNC) of the flowering plants was chilled for 4 different periods (0, 22, 36 and 53 days) in a chamber of 2 7°C, then transplanted to three different conditions, i.e. PHY: 25–20°C day and night temperatures, 16 hours day length, GHL: 10 25°C, 16 hours day length with supplementary light and GHN: 10 25°C, natural day length (10 15 hours). In PHY, FNC bolted and flowered with almost the same leaf numbers in all 4 different chilling treatments. This means that FNC has very low sensitivity and no requirement to low temperature for its reproductive growth. In GHN (short day length), FNC bolted very slowly. Then the bolting and flowering of FNC were promoted by both long day length and high temperature. The newly found bolting characteristics of Osaka Shirona Bansei could be applied to breed unique slow bolting Chinese cabbage (B. rapa L. ssp. pekinensis) which might be non-sensitive to low temperature and its bolting and flowering would be induced with the combination of long day length and high temperature. Using the unique variety, it might be also possible to establish a new cropping type of Chinese cabbage (late autumn sowing, spring harvest).Abbreviations PHY Phytotron, long day and high temperature condition - GHL Greenhouse, long day and medium temperature condition - GHN Greenhouse, natural (short) day and medium temperature condition - FNC A progeny line of Osaka Shirona Bansei which flowered with no chilling treatment - FC A progeny line of Osaka Shirona Bansei which flowered with chilling treatment     

Chromosome association and fertility in hybrids of Iris laevigata Fisch. x I. ensata Thunb.

Summary Chromosome association at MI of PMCs in hybrids of I. laevigata x I. ensata was examined and compared with that of parental species. The mean chromosome association per cell in the parental species was 0.02_I+11.99_II for I. ensata (Kachô, 2n=24), 0.11_I+15.94_II and 0.15_I+15.92_II for I. laevigata (Yukidôrô and wild type, 2n=32), respectively. On the other hand, the mean chromosome association per cell in the hybrids (2n=28) was 20.22_I+3.88_II+0.0046_IV for Yukidôrô × Kachô and 20.92_I+3.54_II for wild type × Kachô. Thus, the hybrids indicated a low homology between I. ensata and I. laevigata, and did not exhibit pollen and seed fertility. The utility of the hybrids was discussed.     

Winter environment increases self seed yield in self-incompatible (SI) Petunia hybrida clones

Summary SI inbreds of P. hybrida and crosses between self-incompatible (SI) petunia plants were brought to flower under winter and summer glasshouse conditions. SI response, as measured by self seed, ranged from zero seed set under both conditions to low or zero seed set during the summer and high seed set during the winter. Some plants produced comparable seed yields during either pollination time. Increased expression of pseudo-self-compatibility (PSC) during the winter months was attributed to a breakdown of the Si system by the low light conditions of Minnesota winters (45°N). Genotypic differences within and between populations in the winter provided differences facilitating selection for increased SI. These differences were masked in some populations by the summer environmental conditions. The use of simulated or natural low light conditions as a technique for selecting for SI should increase selection efficiency.Scientific Journal Series Paper Number 10,499 of the Minnesota Agricultural Experiment Station.     

Inheritance of flower color in Dendranthema grandiflora Tzvelev. (Chrysanthemum morifolium Ramat.) using cultivars and inbreds. I. Plastid pigmentation

Summary Progeny from controlled crosses of 28 garden chrysanthemum (Dendranthema grandiflora Tzvelev.) inbreds in various combinations as males with 3 heterozygous cultivars and 10 inbreds as females were evaluated for plastid pigmentation in a series of field and glasshouse environments. Disomic inheritance of a dominant gene, which acts to inhibit pigmentation, best explained the data. However, 1 of 8 families involving a glasshouse cultivar with colorless plastids (Puritan) as female and inbreds with yellow plastids as males deviated significantly from the expected 1:1 ratio. This family consistently exhibited an excess of plants with colorless plastids. Although parent clones and cloned progeny from inbred parents were scored the same in field and glasshouse environments, reevaluation in the field of all 8 Puritan families, first evaluated in a glasshouse environment, revealed phenotypic misclassification apparently due to environmental effects. An excess of plants with colorless plastids appeared in the glasshouse but evaluation of the same genotypes in the field resulted in an excess of plants having yellow plastids. Submerging ray florets in a hot-water bath revealed yellow plastids masked by vacuolar pigments, thus reducing chances of misclassification. The data suggest that evaluation of highly variable families in a single environment can lead to misclassification of plastid pigmentation. However, even with evaluation in 2 or more environments, certain families may exhibit an excess of plants with colorless plastids.     

Interspecific hybrids from cross incompatible relatives of sweetpotato

Summary Hybrids were obtained from Ipomoea interspecific crosses through ovule culture. The hybridity of the progeny obtained from I. triloba × IitI. trifida and (I. triloba × I. lacunosa) × I. batatas (4x) crosses was established by comparisons of floral morphology and analyses of peroxidase and esterase isozymes. The hybrids displayed the inflorescence type and sepal shape and texture of their male parents, while corolla size and anther and nectary color tended to be intermediate to their parents. The isozyme banding patterns of the hybrids contained bands present in the patterns of each of their parents. Pollen grain viability, measured by aceto-carmine stainability, was 44.1%, 92.3% and 82.4%, respectively, for the I. triloba × I. trifida hybrid and the (I. triloba × I. lacunosa) × I. batatas (4x) hybrids, H₁ and H₂. A controlled pollination study revealed that the I. triloba × I. trifida, and the (I. triloba × I. lacunosa) × I. batatas (4x) hybrids, H₁ and H₂ were partially self fertile with 6%, 70% and 13%, respectively, of the pollinated flowers producing viable seed. Success in backcrossing and sib-mating varied with the cross combination.     

Production of intergeneric hybrid plants between <Emphasis Type="Italic">Sandersonia aurantiaca</Emphasis> and <Emphasis Type="Italic">Gloriosa rothschildiana</Emphasis> via ovule culture (Colchicaceae)

Intergeneric hybrid plants between Colchicaceous ornamental plants, Sandersonia aurantiaca and Gloriosa rothschildiana, have successfully been produced via ovule culture. After 5 days of reciprocal cross-pollination, a few pollen tubes were observed in the ovary. Although seeds were obtained in both reciprocal cross-combinations, they did not germinate under ex vitro conditions. Ovules with placental tissues isolated 14 days after cross-pollination of S. aurantiaca × G. rothschildiana were cultured on a medium containing 0.01 mg l^–1 each of -naphthaleneacetic acid (NAA) and 6-benzyladenine (BA), on which 41.5% of ovules swollen and produced callus-like structures within 10 weeks. When such swollen ovules were transferred to a medium containing 0.1 mg l^–1 each of NAA and BA, 7.5% of the initially cultured ovules produced rhizome-like structures within 6 weeks. Among the rhizome-like structures, those derived from two independent ovules (3.7% of the initially cultured ovules) produced multiple shoots following transfer to a medium containing 0.25 mg l^–1 NAA and 2.5 mg l^–1 BA. Multiple shoot-derived plantlets were established on a plant growth regulator-free medium, and they were successfully transplanted to pots. Early verification of their hybridity was accomplished by flow cytometry (FCM) analysis, chromosome observation and rDNA analysis.     

Triple fusion of the primary endosperm nucleus as a cause of interspecific cross-incompatibility in Avena

Summary Using five diploid, two tetraploid and three hexaploid Avena species (x=7) 78 reciprocal crosses were made. Of these 74 were successfull, though the frequency of seed set varied greatly. The development of hybrid seeds differed widely between cross combinations, especially in reciprocal crosses. Hybrid seeds were grouped into four types, (1) normal kernels, well developed and germinative (designated as D+); (2) shrivelled-empty kernels, which do not germinate (E–); (3) small viable kernels (Rd+) and (4) small inviable kernels (Rd–). Some rare intermediate types were found in certain crosses.The results are well interpreted in terms of a hypothesis of polar-nuclei activation in which the strength of the activating action of the male nucleus, and the reaction of the female nucleus at double fertilization are expressed as activating value(AV) and response value(RV), respectively. The degree of seed failure is closely related to the activation index(AI) of the polar nuclei, AV/2RV (or × 100). In a selfed plant the activation index is always 1/2=0.5 (or50%), and this usually results in the formation of normal seeds. If AI deviates from 50% the endosperm often stops developing or degenerates.Based on the degree of abnormality of hybrid seeds, activating values of the ten species were arbitrarily assigned from 0.4 in A. ventricosa (2x) to 3.0 in A.sterilis (6x). For comparison A.strigosa (2x) was used as a standard and set at 1.0. Among the 74 succesful interspecific crosses the AI of the polar nuclei varied widely, from 7 to 375% Generally speaking, AI values of less than 20, 20–30, 30–80, and more than 80% show the R-, Rd+, D+ and E-kernel types, respectively. In other words, if the AV of the pollen parent is < 40 or >160% that of the maternal parent hybrid seeds fail to develop. Thus in double fertilization of Avena or probably angiosperms, the triple fusion of two polar nuclei with a secondary male nucleus is apparently a sexual isolation mechanism, being a barrier to interspecific hybridization.Professor Emeritus of Kyoto University, Faculty of Agriculture, Kyoto.     

Genetics of resistance to five strains of turnip mosaic virus in Chinese cabbage

Summary Inheritance of resistance to turnip mosaic virus (TuMV) strains C1, C2, C3, C4, and C5 in Chinese cabbage (Brassica campestris subsp. pekinensis) was evaluated using monoclonal antibodies. Crosses were made between a resistant line, 0–2, and four susceptible line. Seoul (SE),SSD31 (SS), Cheongbang (CH), and Yaki 1 ho (YA), to determine the inheritance of resistance of 0–2 in different genetic backgrounds. Resistance to TuMV was controlled by a single dominant gene or double dominant genes depending on the strain and cross. The resistance genes of 0–2 were modified by susceptible parents such that a single dominant gene was involved in the SS×0–2 combination, but double dominant genes in the SE×0–2 against TuMV-C3 or TuMV-C5. ELISA tests using inoculated and noninoculated leaves in the same plant suggested that the dominant resistance genes inhibit virus movement rather than virus multiplication.     

Variation for agronomic and processing traits in Solanum tuberosum haploids × wild species hybrids

Summary The broad range of wild and cultivated species relatives of the commerical potato (Solanum tuberosum L.), guarantees the existence of a gene reservoir to be screened for traits that are absent or present only in low frequencies in the cultivated germplasm. Haploids (2n=2x=24) extracted from the cultivated tetraploid (2n=4x=48) germplasm cross easily with diploid (2n=2x=24) potato species and produce fertile progeny. As most haploid × species hybrids tuberize under long day conditions they can be maintained clonally and evaluated for the traits of interest. Three populations involving Tuberosum haploids × Solanum bukasovii (tub x buk), Tuberosum haploids × Solanum sparsipilum, (tub × spl) and Tuberosum haploids × Solanum berthaultii (tub x ber) clones, were planted at two locations in Wisconsin. The haploids were derived from W231, a selected clone from the University of Wisconsin Potato Breeding Program. The objectives were: to evaluate the H-S populations for agronomic and processing traits, and to determine the phenotypic associations between them. Data were recorded on haulm maturity (HM), tuber weight (TW) and tuber number (NT) per plant, specific gravity (SG), chip color after harvest (CH), and chip color after storage at 4° C and one week of reconditioning at room temperature (CH1). Results for SG and CH indicated good potential of the germplasm evaluated to introgress these traits into the commercial potatoes. For instance, the SG mean for tub x buk, tub x spl and tub x ber were 1.079, 1.086 and 1.082, respectively, and their means for CH were 4.8, 3.9 and 3.5. Chip color after storage and reconditioning was found in low frequency in the populations. Four clones in the tub x spl population, and three clones in the tub x ber population had CH1 4.0, the commercially acceptable score for this trait. Significant (p 0.01) phenotypic correlations (r) were found between HM and SG (r=–0.46 in tub x buk, r=–0.61 in tub x spl, and r=–0.34 in tub x ber), NT and TW (r=0.79 in tub x buk, r=0.88 in tub x spl, and r=0.71 in tub x ber), and TW and SG (r=0.40 in tub x buk, and r=0.36 in tub x spl). The correlation coefficients between processing traits were not significant, which may indicate the presence of separate genetic mechanisms governing the inheritance of these traits.     

Oil content, tocopherol composition and fatty acid patterns of the seeds of 51 Cannabis sativa L. genotypes

The oil content, the tocopherol composition, the plastochromanol-8 (P-8) content and the fatty acid composition (19 fatty acids) of the seed of 51 hemp (Cannabis sativa L.) genotypes were studied in the 2000 and 2001 seasons. The oil content of the hemp seed ranged from 26.25% (w/w) to 37.50%. Analysis of variance revealed significant effects of genotype, year and of the interaction (genotype × year) on the oil content. The oil contents of the 51 genotypes in 2000 and 2001 were correlated (r = 0.37**) and averaged 33.19 ± 1.45% in 2000 and 31.21 ± 0.96% in 2001. The -tocopherol, -tocopherol, -tocopherol, P-8- and -tocopherol contents of the 51 genotypes averaged 21.68 ± 3.19, 1.82 ± 0.49, 1.20 ± 0.40, 0.18 ± 0.07 and 0.16 ± 0.04 mg 100g^–1 of seeds, respectively (2000 and 2001 data pooled). Hierarchical clustering of the fatty acid data did not group the hemp genotypes according to their geographic origin. The -linolenic acid yield of hemp (3–30 kg ha^–1) was similar to the -linolenic acid yield of plant species that are currently used as sources of -linolenic acid (borage (19–30 kg ha^–1), evening primrose (7–30 kg ha^–1)). The linoleic acid yield of hemp (129–326 kg ha^–1) was similar to flax (102–250 kg ha^–1), but less than in sunflower (868–1320 kg ha^–1). Significant positive correlations were detected between some fatty acids and some tocopherols. Even though the average content of P-8 in hemp seeds was only 1/120^th of the average -tocopherol content, P-8 content was more closely correlated with the unsaturated fatty acid content than -tocopherol or any other tocopherol fraction. The average broad-sense heritabilities of the oil content, the antioxidants (tocopherols and P-8) and the fatty acids were 0.53, 0.14 and 0.23, respectively. The genotypes Fibrimon 56, P57, Juso 31, GB29, Beniko, P60, FxT, Félina 34, Ramo and GB18 were capable of producing the largest amounts of high quality hemp oil.     

Identification of RAPD markers linked to linolenic acid genes in rapessed

Summary The inheritance of the low linolenic acid content (derivated from mutant lines) in rapeseed was investigated. Molecular techniques of gene mapping through RAPD markers were applied on a microspore-derived progeny from a high × low linolenic acid F₁ hybrid. Bulked segregant analysis made it possible to test rapidly number of RAPD primers. Two linkage groups of 6 markers (72.7 cM and 75.6 cM) were determined. Each corresponded to a major QTL which explained 24% and 30.7% of the total phenotypic variation of the linolenic acid content. It was confirmed that two independant mutations were implied in the low linonenic acid content.     

Inheritance of the virgata pattern of partly colored seed coats in ‘Early Giant’ common bean

The inheritance of the virgata pattern of partly colored seed coats found in common bean (Phaseolus vulgaris L.) Early Giant (EG) was studied by a series of test crosses with line 5-593 and genetic stocks developed by backcrossing selected genes into the recurrent parent 5-593, a Florida dry bean breeding line with a self-colored, black seed coat with genotype T Z Bip P [C r] J G B V Rk. Analysis of the F₂ from the cross EG × 5-593 led to the hypothesis that the virgata pattern of EG has genotype t z bip^vgt, where vgt stands for virgata. The test cross EG × t z virgarcus BC₃ 5-593 confirmed the hypothesis that EG carries t z from data recorded in F₁, F₂, and 27 F₃ progenies from randomly selected F₂ plants. The F₃ segregation was also consistent with the hypothesis that a single recessive gene converts virgarcus into virgata. The test cross EG × t z bip bipunctata BC₃ 5-593 failed to show genetic complementation in F₁ progeny, and the F₂ segregated 3:1 for the parental phenotypes virgata and bipunctata, respectively. Including previously published data, all possible crosses were made among bipunctata, virgata, and virgarcus parents, supporting a multiple allelic series at Bip. We propose the gene symbol bip^vgt for the new allele at Bip, where the allelic series has the order of gene dominance Bip > bip^vgt > bip. Based on test crosses, the complete seed-coat color and pattern genotype of EG is tz bip^vgt P [C r] J G B v^lae rk^d.