Genes for resistance to stripe rust in four spring wheat varieties

Summary Four spring wheat (Triticum aestivum L.) varieties differing in origin and reaction in the seedling stage to pathotype CDL-6 (extant in California) were intercrossed and examined in greenhouse conditions in F₁, F₂, and F₃ generations. Digenic and transgressive segregation was found in all crosses. The four varieties each had infection types (1 immune, 9 susceptible) and putative resistance genes as follows: Anza, IT 7, YrA; Glennson 81, IT 2, Yr9; Yecora Rojo, IT 6, YrC; and Ollanta, IT 4–6, YrL. Anza was classified as susceptible, Yecora Rojo and Ollanta as intermediate in seedling resistance, and Glennson 81 as resistant in the seedling stage.     

Development of a triticale resistant to the greenbug: An historical perspective

Summary A greenbug [Schizaphis graminum (Rondani)] resistant strain of rye (Secale cereale L.) Insave F.A. from Argentina was crossed with Chinese Spring wheat (Triticum aestivum L.) and also with Elbon and Balbo cultivars of common rye. Juvenile plants of the primary wheat X rye hybrid were treated with colchicine. Partially fertile amphidiploids were obtained that are resistant to greenbug Biotypes B and C. F₁ and F₂ populations of seedling plants derived from crosses of Insave F.A. with Elbon and Balbo rye were tested for reaction to the greenbug to determine the genetic basis of inheritance. The results confirmed previous reports that resistance in Insave F.A. is conditioned by a single dominant gene.Deceased     

Inheritance of resistance to powdery mildew (Erysiphe graminis f. sp. hordei) in eleven primitive barley varieties

The inheritance of the powdery mildew resistance of eleven primitive barley varieties was investigated. crosses with varieties with identified resistance genes revealed that at least three different genes are present in a group of six genotypes from Greece (Hor736, Hor847, Hor878, Hor1159, Hor1379 and Hor1873) and one from Turkey (Hor1188). One dominant gene is common to these seve genotypes and in the Greek accessions a second gene is present. The expression of this second gene was respectively dominant in the crosses with Hor736 and Hor1159, recessive in the crosses with Hor878 and Hor1873, and depended on the employed powdery mildew isolate in the crosses with Hor847 and Hor1379. The detected genes differ from the resistance genes of the crossing partners, viz. Ml-al2, Ml-(Ab), Ml-(CP) and Ml-(1402). The accessions from China (Hor824 and Hor4021) each possess two resistance genes which differ from Ml-a12, Ml-(La) and Ml-(CP). The major gene is common to both accessions and is either identical, allelic or closely linked to a gene in the variety Nigrate. The Columbian accession Hor1894 possesses one resistance gene linked to a resistance gene in Nigrate but this gene differs from the Ml-a locus. The variety Palestine (Hor3997) possesses two resistance genes of which one is allelic or closely linked to Ml-(at).     

Molecular and biological studies on male sterile cytoplasm in Cruciferae. II. The origin of Ogura male sterile cytoplasm inferred from the segregation pattern of male sterility in the F1 progeny of wild and cultivated radishes (Raphanus sativus L.)

Summary To determine the origin of Ogura male sterile cytoplasm in radish (Raphanus sativus L.), wild and cultivated radishes were crossed. Three types of progeny resulted from the F₁ hybrids between the wild radish from Kushikino with Ogura-type mtDNA and the cultivars (Uchiki-Gensuke or Comet). The segregation patterns of the male sterility were compared with those of Ogura cytoplasm. The male sterility induced in the F₁ hybrid was maintained by crossing with Uchiki-Gensuke, that maintains Ogura male sterility. In the two types of progeny, in which Comet (a restorer of Ogura cytoplasm) was used as one of the parents, both fertile and sterile plants segregated at the predicted ratio on the assumption that a single dominant fertility restoring gene exists in the restorer. From these results, we concluded that the Ogura cytoplasm is identical to that of the wild radish, and the former originated in a population of Japanese wild radish.     

Inheritance studies of characters associated with floating habit and their linkage relationship in rice

Summary Deep water rice varieties in general have certain peculiar characters which are associated with floating habit. These characters are (i) early nodal differentiation, (ii) nodal rooting, (iii) spreading habit, (iv) awned grains, (v) brown hull colour, (vi) red pericarp (red rice), and (vii) seed dormancy. Inheritance of these characters and linkage relationship of genes governing these characters were studied in a cross between Pankaj (non floating) and Nageribao (floating) rice varieties. Nageribao, a cultivar from Assam possesses these characters.Early nodal differentiation was observed to be controlled by a single dominant gene, designated as Nd. Nodal rooting was controlled by two dominant complementary genes, designated as Nr ₁ and Nr ₂. We found an inhibitory factor for spreading habit and one for brown hull colour in Pankaj; the operation of two dominant duplicate genes An ₁ and An ₂ for controlling awning characters, a single dominant gene Rd for red pericarp colour and a single dominant gene Gd for grain dormancy. Joint segregations between these characters resulted in the assignment of genes in the X linkage group of indica rices with estimated map distances based on the cross-over values. The genes An (awning), Es (spreading habit), Nr (nodal rooting) and Nd (nodal differentiation) were observed to be associated with each other. The gene for red pericarp (Rd) was observed to be linked with the grain dormaney gene Gd.     

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.     

The introgression of S alleles into forage rape,Brassica napus L. from turnip. Brassica campestris L. ssp. Rapifera

Summary Forage rape. B. napus, is self-compatible, the work described illustrates the introgression of functional incompatibility alleles into B. napus from turnips, B. campestris, in two generations. By grading seed, produced by backcrossing turnip/rape hybrids to rape, the frequency of 2n=38 semi articial B. napus recovered, amply justifies the cytological screening involved in such breeding programmes.     

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.     

Linkage in Spinacia oleracea L. of two race-specific genes for resistance to downy mildew Peronospora farinosa f. sp. spinaciaeByford

Summary The genetics of resistance to races 1 and 2 of downy mildew Peronospora farinosa f. sp. spinaciae in the spinach variety Nores was investigated in crosses and backcrosses with the susceptible variety Eerste Oogst. Resistance appears to be governed by two closely linked genes in coupling phase with a recombination percentage of 4.6.     

The transfer of triazine resistance from Brassica napus L. to B. oleracea L. III. First backcross to parental species

Summary Atrazine resistant Brassica napus × B. oleracea F₁ hybrids were backcrossed to both parental species. The backcrosses to B. napus produced seeds in both directions but results were much better when the F₁ hybrid was the pollen parent. Backcrosses to B. oleracea failed completely but BC₁s were rescued by embryo culture both from a tetraploid hybrid (2n = 4x = 37; A₁C₁CC) and sesquidiploid hybrids (2n = 3x = 8; A₁C₁C). Progeny of crosses between the tetraploid hybrid and B. oleracea had between 25 and 28 chromosomes. That of crosses between the sesquidiploid hybrid and B. oleracea had between 21 and 27. A few plants that had chromosome counts outside the expected range may have originated from either diploid parthenogenesis, unreduced gametes or spontaneous chromosome doubling during in vitro culture. Pollen stainability of the BC₁s ranged from 0% to 91.5%. All the BC₁s to B. oleracea were resistant to atrazine.     

Breeding for resistance to yellow disease of hyacinths. II. Influence of flowering time,leaf characters,stomata and chromosome number on the degree of resistance

Summary Analysis of an incomplete diallel design with 14 hyacinth cultivars and 4 wild accessions of Hyacinthus orientalis showed a significant GCA component for resistance to yellow disease. The late flowering hyacinth cultivars King of the Blues and Marconi and the early flowering Hyacinthus orientalis 70129 were found to be the best combiners for yellow disease resistance. Within a cultivar, the degree of earliness itself was not associated with the degree of resistance. Correlation coefficients of leaf characters and degree of resistance showed that hyacinths with short and/or narrow leaves are generally more resistant than those with long and/or broad leaves. Tetraploid cultivars with few, large stomata tend to be susceptible, diploid ones with many small stomata tend to be the more resistant.     

α-Tomatine and other steroidal glycoalkaloids in fruits of tomato lines resistant to the glasshouse whitefly (Trialeurodes vaporariorum Westw.)

Summary The total steroidal alkaloid compositions of the mature-harvested fruits of the tomato cultivar Allround (Lycopersicon esculentum), of the species L. hirsutum glabratum, resistant to the glasshouse whitefly (Trialeurodes vaporariorum), and of four resistant lines were determined by capillary gas chromatography. The contents of -tomatine in the red-ripe fruits of Allround and in those of the lines were low (5 mg/kg fresh weight). The green-mature fruits of the wild species had a high content (3390 mg/kg fresh weight) of -tomatine. The total alkaloid profiles of Allround and of the lines were similar. Comparison of flame ionisation detector response with thermoionic detector response indicated that in addition to tomatidine, the aglycone of -tomatine, a small amount of one other steroidal alkaloid might be present in Allround and in the lines. The wild species contained five compounds which possibly are steroidal alkaloids.The safety level of -tomatine in tomatoes is discussed. It was concluded that, in respect of the glycoalkaloids of the mature-harvested fruits, the resistant tomato breeding lines are as safe for human cosumption as the standard cultivar.     

Effect of Zinnia angustifolia HBK genotype on morphology and flowering of Z. angustifolia × Z. elegans Jacq. hybrids

Summary Interspecific hybrids were generated from crosses between 4 Zinnia angustifolia clones (maternal parents) and an inbred line of Z. elegans Orange King (paternal parent) to investigate the influence of Z. angustifolia genotype on morphology and flowering of hybrids. Leaf length, leaf width, flower diameter, number of ray petals, and days to flowering of interspecific hybrids were significantly influenced by Z. angustifolia clonal genotype. Genetic analysis of hybrid morphology and development was performed using 2 parental Z. angustifolia clones and 18 F₁ (9 seedlings from each of 2 populations generated from reciprocal crosses between parental clones) as maternal parents in crosses with Z. elegans Orange King. Genotype of Z. angustifolia significantly affected plant height, fresh weight, number of nodes, and days to flowering of interspecific hybrids. Control of these traits was through the Z. angustifolia nuclear genome. Improvement in interspecific hybrid morphology or development, i.e., shorter stature, earlier flowering, or larger flowers, may be possible by selection of superior-performing Z. angustifolia clones as parents.     

Isolation of a pure thornless loganberry by meristem tip culture

Summary Thornless Loganberry (TL) is a periclinal chimeral blackberry in which a layer of mutant (thornless) epidermis surrounds a core of wild-type (thorny) tiusse. Due to its chimeral arrangement, TL produces thorny adventitious root cuttings and thorny offspring. To separate the chimera into its components parts, meristems of TL were grow in vitro on modified Murashige and Skoog medium to yield callus and adventitious shoots. One of these shoots has survived, flowered, and produced thornless offspring from seed. The importance of this non-chimeral TL is discussed.List of terms BA 6-benzylaminopurine - GA₃ gibberellic acid - NAA naphthalene acetic acid - hybridberry polyploid bramble interspecific hybrids - MS Murashige & Skoog (1962) high mineral salt medium - TL Thornless Loganberry - TL_tc tissue culture-derived (non-chimeral) Thornless Loganberry     

Productivity of F hybrids of botanical varieties ofBrassica oleracea L.

Summary F₁ hybrids were obtained by making pair-crosses between nine botanical varieties ofBrassica oleracea. Although non-inbred parents were used, their yield was surpassed by all F₁ hybrids. The highest yields were shown by the crosses marrow-stem kale × sprouting broccoli and marrow-stem kale × cauliflower while the highest consumable yield (assessed by feeding plants to sheep) was that of F₁ hybrids marrow-stem kale × cauliflower and wild cabbage × cauliflower. A scheme for the production of F₁ hybrid seed is suggested, based upon an adaptation ofThompson's (1964) Triple-cross technique.     

Transfer of resistance to race 2 of Plasmodiophora brassicae from Brassica napus to cabbage (B. oleracea var. capitata). II. Meiosis in the interspecific hybrids between B. napus and 2x and 4x cabbage

Summary Meiosis in 14 interspecific F₁ hybrids with three chromosomal levels (triploid, tetraploid, hexaploid; 2n=28, 37 and 55) between Brassica napus L. and 2x and 4x cabbage (B. oleracea var. capitata L.) was studied. The oleracea genome from B. napus maintained close homology with the c genome of cabbage while the campestris genome of B. napus showed partial homology with the c genome contained in the hybrids. Genotypic influence on chromosome pairing was indicated. Structural chromosome differences and spontaneous chromosome breakage and reunion were suggested as causes for the abnormalities which related to the unbalance of the genotypes. The divergence of the genomes of B. napus and B. oleracea and the need for the qualification of the term secondary association were discussed.Contribution No. J. 673, Research Station, Agriculture Canada, St. Jean, Québec.     

Morphology,cytology and forage potential of Pennisetum americanum (L.) K. Schum. x P. Purpureum Schum. amphidiploids

Summary F₁ hybrids between short-day photoperiod- sensitive maiwa bulrush millet, Pennisetum americanum (2n=14), and elephant grass, P. purpureum (2n=28), are triploid (2n=21), sterile, and can only be propagated vegetatively. Fertile amphidiploids, (2n=42, with 21 bivalents) were produced by colchicine treatment. Good seed set was obtained upon selfing the amphidiploids and the progeny exhibited variable pollen fertility and bivalent univalent and multivalent formation.Reciprocal crosses between elephant grass and the colchicine-induced amphidiploid failed to produce seeds. The maiwa millet x amphidiploid cross resulted in poor seed set and the reciprocal failed. Maiwa x amphidiploid hybrids were pollen sterile with 2n=21, rather than the expected 2n=28, indicating chromosome elimination.Morphologically, the amphidiploids and maiwa x amphidiploid hybrids closely resembled elephant grass and the F₁ hybrid. The amphidiploids showed no superiority over the F₁ hybrid and elephant grass in either forage yield or quality but one maiwa x amphidiploid genotype surpassed a promising local elephant grass selection in forage dry matter yield and flowered for a relatively short period.     

Glandular hair densities in three perennial Medicago species

Summary Eight triazine resistant (Brassica napus x B. oleracea) x B. oleracea interspecific hybrids with chromosome numbers ranging from 25 to 27 were backcrossed a second time to B. oleracea but no seed was formed. However, in vitro embryo rescue on 77 developing ovules yielded nine BC₂ plants with chromosome numbers between 19 and 25 and in which the herbicide resistance was still strongly expressed. Three of these plants (NOH-8B2B1, 2n=20; NOH-8B2B3 and NOH-8B2B4, 2n=19) were backcrossed again to B. oleracea. Two of the three plants produced seed which germinated to produce triazine resistan BBC₃s with 18, 19 or 20 chromosomes. The triazine resistant B. campestris cytoplasm has now been stabilized in B. oleracea.     

Stability of forage yield and quality in pearl millet hybrids heterogenous for rust resistance

Summary The susceptible pearl millet hybrid Tifleaf 1, the resistant hybrid Tifleaf 2, and two experimental 3-way hybrids with different proportions of resistant and susceptible plants were evaluated for rust resistance and forage yield and quality in 1990, 1991, and 1992. Different environmental conditions were obtained by varying planting date, planting density, and fungicide applications across three years of evaluation in the field. Rust severity of forage was negatively correlated with late season green yield, dry matter yield, in vitro dry matter digestibility, and digestible dry matter yield. The stability across environments of the 3-way hybrids was intermediate between resistant Tifleaf 2 and susceptible Tifleaf 1 for rust severity and the yield and quality measurements negatively correlated with rust severity. Mixtures of resistant and susceptible plants would probably provide greater control of rust than measured in these small-plot experiments. Although a mixture of resistant and susceptible plants appears to provide an alternative to monogenic control of rust in forage pearl millets, identification and utilization of additional sources of resistance would be beneficial to improve the performance of 3-way hybrids.     

Chromosome association and pollen fertility in some interspecific hybrids of Lilium

Summary Meiotic observations in PMCs were made in eight kinds of interspecific hybrids in Lilium. Three hybrids, 6134-S × L. cernuum. L. regale × L. leichtlinii maximowiczii and L. auratum platyphyllum × L. henryi showed respectively the mean chromosome association frequencies of 1.4_II, 0.8_II and 1.5_II per cell at MI which were the lowest values hitherto reported in Lilium hybrids. In L. longiflorum × L. henryi, 33.3° of the cells had 1 or 2 multivalents of three to five chromosomes in addition to uni- and bivalents. 12° bivalents and 12 univalents were invariably observed in the triploid hybrid L. longiflorum × L. cernuum. The hybrids between the species belonging to the different sections of the genus generally showed high pollen sterility, with some exceptions. A more or less remote genomic homology was found between the different sections in Lilium.