In most lisianthus flowers anthocyanin coloration occurs very late in petal development just preceding unfurling of the petals. We have developed through breeding several lisianthus lines in which coloration occurs at a very early developmental stage. Using these lines and lines in which coloration occurs at a late stage, we study the trait of anthocyanin synthesis timing both genetically and biochemically. The early coloration trait is shown to be recessive for the F1 generation, and probably involves more than one gene. Our biochemical study show that three key enzymes in the metabolic pathway of anthocyanin synthesis (chalcone synthase (CHS), chalcone isomerase (CHI) and flavone 3-hydroxylase (F3H)) accumulate early on during bud development in all lines. Hence, the control of the pathway is either at enzymes late in the pathway or is postranslational.

We have developed an efficient technique for shoot regeneration of lisianthus from leaf explants by direct organogenesis. Transformation experiments with DNA were carried out using Agrobacterium tumefaciens carrying the Ti plasmid pBI121 which contained the genes NPTII and (beta-glucuronidase) GUS fused to the 35S promoter of the CaMV. Kanamycin-resistant shoots of lisianthus were regenerated on Murashige and Skoog (MS) medium with 6-Benzylaminopurine (BA) showed GUS activity, as determined by the appearance of a blue precipitate after incubation with the substrate X-Gluc (5-bromo-4-chloro-3-indolyl glucuronide).

In 1992 viruslike symptoms appeared on lisianthus plants grown at different locations in Israel. The symptoms included distortion of the growing tips, cup-shaped leaves, and swelling of veins on the lower surface of the leaves. Plants infected at an early stage did not yield flowers, but late infections did not impair flowering. The viral causal agent of the disease was purified from infected plants and identified with a molecular probe prepared from cloned tomato yellow leaf curl virus (TYLCV) DNA and a specific antiserum against the virus. Purified preparations were infectious to healthy lisianthus in transmission experiments with Bemisia tabaci. These data confirmed that lisianthus leaf curl is caused by TYLCV. This devastating disease has become a limiting factor in the expansion of lisianthus cultivation in Israel.

Accessions ofM. tricuspidata (L.) R. Br.,M. aspera Boiss. andMatthiola longipetala (Vent.) DC. were tested for their reaction to bacterial blight of stock (M. incana R. Br.), caused byXanthomonas campestris pv.incanae. Potted plants were sprayed with bacterial cell suspension, adjusted to 108 cells/ml. The tested accessions of the three species were found highly resistant, while control plants ofM. incana were severely infected. InterspecificF 1 hybrid plants betweenM. incana andM. tricuspidata also exhibited high resistance to the disease. The implications and the expected difficulties in breeding stock for bacterial blight resistance are discussed.

The variation in growth characteristics among lisianthus (Eustoma grandiflorum Shinn.) genotypes was investigated. The genetic control of several growth parameters was studied by analysing parental, F1, BC1 and F2 populations. The parameters analysed were stem elongation rate (SE), stem diameter (SD), leaf width (LW), number of nodes (NN), node length (NL) and days to flowering (DF). The genotypes tested exhibited great variation for all parameters. A particularly wide variation was noted for SE, ranging from 3 to 56 mm/week. This variation was partially attributed to a differential sensitivity to rosette formation. There was a marked positive heterosis for SE, SD, LW and NN; these parameters proved to be genetically correlated within segregating populations. DF was slightly negatively correlated with SE, NN and NL. It was concluded that SE and DF were independently controlled.

The genetics of chill-related seed dormancy, exhibited by a lisianthus (Eustoma grandiflorum) genotype native to North America, was investigated. Less than 1 % of the seeds germinated by direct hydration at 20 degrees C, while full germination (98 %) was attained by chilling imbibed seeds, for at least 11 days, at 3 degrees C, before transferring them to 20 degrees C. The inheritance of seed dormancy was analysed in F-1, BC1 and F-2 populations, derived from mating between a normal non-chill-requiring genotype (P-1) and the above chill-requiring genotype (P-2). F-1 seeds, of both reciprocals, and BC1 (P-1) seeds were all non-dormant. The proportion of seed dormancy in F-2 and BC1 (P-2) was 0.06 and 0.68, respectively. The inheritance model proposed includes six diallelic loci with cumulative effects, in which the presence of at least nine 'dormancy-conferring' alleles is necessary for inducing phenotypic seed dormancy. Possible implications of inherent seed dormancy on the utilization of native lisianthus germplasm for breeding are discussed.

The inheritance of speed of germination and its genetic relations with seed dormancy was investigated in lisianthus (Eustoma grandiflorum). The study was based on data from parental, F1, BC1F1 and F2 generations of a cross between a normally germinating genotype (P1) and a chill-requiring genotype (P2). The mean post-chilling germination speed of P2 was considerably lower than that of P1. Germination speed was found to be under nuclear embryonic control. Analysis of generation means for prechilled seeds revealed an additive gene action with complete dominance of the alleles conferring higher germination speed, since the means of the F1 and the BC1(P1) were indentical to that of P1. Such dominance was not found for unchilled seeds, in which the mean germination speed of the F1 and the BC1(P1) was lower than that of P1. It was hypothesized that slow germination speed was induced by pleiotropic effects of seed dormancy alleles. Seed prechilling seemed to eliminate these effects in progeny heterozygous for dormancy alleles, but not in progeny homozygous for dormancy alleles.

Inheritance of fatty acid composition was studied in an F1 diallel cross in Sinapis alba. Crosses were made among accessions having contrasting amounts of oleic (C18:1) and erucic (C22:1) acid. Concentrations of oleic, linoleic (C18:2), eicosenoic (C20:1) and erucic (C22:1) acids were determined by gas-chromatography for each mating combination. Genetic analysis confirmed that the composition of the fatty acids was controlled mainly by the nuclear genes of the embryo. Additive gene action with partial dominance for the reducing alleles was noted for oleic and linoleic acids, while erucic acid showed an additive mode of inheritance with partial dominance for the enhancing alleles. Positive heterosis was demonstrated for eicosenoic acid content. Erucic acid content was strongly negatively correlated with oleic acid, suggesting a genetic interdependence between the two fatty acids. Broad-sense and narrow-sense heritability estimates for each of oleic, linoleic and erucic acids were very high, due to low between-plants non-genetic component of variance.

The inheritance and linkage relationships of a leaf morphology gene of Matthiola incana were investigated. The allele for sinuate leaf shape, c, was found to be recessive to the allele for normal entire leaf, C. The c allele was tightly linked to the recessive allele for double flowering, s. The recombination frequency between the two loci was close to zero. The mode of inheritance of the C gene was in accordance with the hypothesis that a pollen lethal gene is responsible for the constant 1:1 segregation ratio of double-flowered (= male sterile) to single-flowered (= fertile) plants in most M. incana breeding lines. The sinuate leaf allele seemed to reduce the frequency and delay the flowering of double-flowered plants. The importance of the C gene as a double flowering marker in the cultivation and the breeding of M. incana is discussed.

A study was made of the inheritance of stem elongation rate during early (SER1) and late (SER2) vegetative growth period, of mean leaf width (MLW) and of days to flowering (DTF) in lisianthus (Eustoma grandiflorum Shinn.). The analysis was based on the data of an Fl diallel cross between different breeding lines. Marked directional heterosis was found for SER1, SER2 and MLW, but not for DTF, in which the dominance effects were incomplete and non-directional. SER1 and SER2 were positively correlated with MLW, but negatively correlated with DTF. The implications and the potential of heterotic growth rate of Fl hybrid lisianthus are discussed.

Acanitum napellus, a cut flower crop, was tested for its potential as a flowering potted plant. Paclobutrazol was used as a growth-retardant agent, applied by dipping the tubers before planting or drenching the growth medium, 2 weeks after planting. Paclobutrazol applications in the range of 12.5–25 p.p.m. (dip) and 0.5–2 mg pot−1 (drench), reduced plant height and inflorescence length, but the reduction in plant height was more moderate in the case of medium drench treatments. Increasing concentrations of paclobutrazol above these levels had no significant additional effect. Flowering potted plants were considered commercially desirable when the plant height was 20–30 cm and inflorescence length about 15 cm; this ratio was obtained in plants developed from tubers dipped in 12.5 p.p.m. paclobutrazol.

Upper, middle and lower short root segments of Asclepias tuberosa were planted in 21 pots, using various planting positions. Plants were grown in a heated greenhouse, under controlled 2516°C (D/N) temperature and 16 h day length. Shoots initiated from the proximal end and roots from the distal end of each root segment, regardless of the orientation to gravity. The upper segments emerged and flowered much earlier than the middle or lower segments; the middle segments emerged later than the lower segments. Main stem length and total branching length were considerably greater in the upper segments compared with the middle or lower segments. Planting position had no significant effect on the growth parameters measured.

The inheritance of flowering time (FT) in a cross between early-flowering (P1) and late-flowering (P2) Matthiola incana genotypes, was investigated. The distribution of FT in F1, F2 and BC1 generations indicated an additive genetic control with partial dominance of earlines alleles, particularly with regard to double-flowered plants. Single-flowered plants flowered earlier than double-flowered plants, averaged within both parental lines; however, the mean difference between singles and doubles was 16 days for P1 as compared with 6 days for P2. This flower-doubleness related delay in FT was found to be heritable, by analysis of F3 family means. The implications of these results on the breeding of stock cultivars is discussed.

ABSTRACT Seeds of early-, middle- and late-flowering breeding lines of common stock, Matthiola incarta (L.) R. Br. cultivated under field conditions, were evaluated for their fatty acid compositions. Seeds of early-flowering breeding lines accumulated less linolenic acid (C 18:3) and more oleic acid (C 18:1) than those of late-flowering breeding lines harvested at the same time. Yield parameters, such as number of seeds per pod and number of pods per plant were lower in early-flowering breeding lines than in the late-flowering ones. However, under a controlled-temperature regime, the fatty acid compositions of all breeding lines were affected by temperature in the same manner: higher linolenic acid levels and lower oleic acid levels were observed in seeds which developed at lower temperatures (12–17 °C).

Table 1. Effects of substrate drench of paclobutrazol on growth and flowering of an early flowering (‘Midget-Red’) and late-flowering (‘Lavender’) cultivar of Matthiola incana. Matthiolu incana is an annual-biennial ornamental crop, widely used throughout the world for fresh flowers and gardens. None of the cultivars is compact enough for use as a flowering potted plant. The objective of this study was to determine the effect of substrate drench with 1-(4-chlorophenyl)-4,4dimethyl-2(1 H -1,2,4-triazol-1-yl)pentan301 (paclobutrazol) on the growth and flowering of potted M. incana seedlings. We used ‘Midget-red’ (Takii’s, Kyoto, Japan), an early flowering, short cultivar and ‘Lavender’ (Van-Egmond’s, Leiderdrop, Holland), a late-flowering, medium-stature cultivar. Seeds were sown in a plastic greenhouse on 18 Jan. 1991. Seedlings (20 days old) were potted in 12-cm-diameter (l.2-liter) pots, containing 2 coarse sand : 1 peat substrate (v/v). Plants were grown outdoors and fertigated daily with 50 mg N/liter from 20N9P-16K. Both cultivars were treated with paclobutrazol 20 days after potting. ‘MidgetRed’ was at first-bud-appearance stage when treated, while ‘Lavender’ was vegetative. Paclobutrazol solutions were applied as a substrate drench, using 50 ml/pot that supplied 0.25,0.5, or 2.0 mg paclobutrazol/pot. Control plants were not treated. Data taken included stem (below inflorescence) and inflorescence lengths and flowering date. The percentage of flowers senesced within each inflorescence (one inflorescence per plant) of ‘Midget-Red’ was recorded 30 days after the beginning of anthesis. The design included four replicates (single potted plants) for each treatment and four replicates for the control (untreated plants), arranged in four randomized blocks. Data were subjected to linear, quadratic, and cubic regression analyses (control plants were included as 0.0 mg paclobutrazol/pot).

The fatty acid composition of seed-oil of breeding lines and F hybrids of was analyzed, using direct esterification and gas chromatography. The breeding lines tested differed significantly with respect to the levels of palmitic, oleic, linoleic and linolenic acids. Embryonic-stage heterosis in linolenic acid concentration was demonstrated by F hybrid seeds, derived from mating horticulturally different lines of . Linolenic acid content was negatively correlated with both oleic acid content (r=−0.85) and linoleic acid content (r=−0.66). None of the breeding lines or the F hybrids significantly passed the limit of 67% linolenic acid. Possible genetic and biochemical explanations for the above phenotypic data are discussed.

The fatty acid composition of seed-oil of breeding lines and F1 hybrids of Matthiola incana was analyzed, using direct esterification and gas chromatography. The breeding lines tested differed significantly with respect to the levels of palmitic, oleic, linoleic and linolenic acids. Embryonic-stage heterosis in linolenic acid concentration was demonstrated by F1 hybrid seeds, derived from mating horticulturally different lines of M. incana. Linolenic acid content was negatively correlated with both oleic acid content (r=−0.85) and linoleic acid content (r=−0.66). None of the breeding lines or the F1 hybrids significantly passed the limit of 67% linolenic acid. Possible genetic and biochemical explanations for the above phenotypic data are discussed.

AbstractThe genetics of resistance to Septoria glume blotch (caused by the pathogen Septoria nodorum Berk.) in the wild wheat species Ae. longissima was investigated. The resistance was characterized by two parameters measured on detached leaves — lesion size (LS) and length of latent period (LP), and by disease severity (DS) under field conditions. Generations F1, F2 and F3, derived from a cross between two Ae. longissima accessions, were analyzed. The two parameters measured on detached leaves (LS and LP) were highly correlated, while DS was moderately correlated to both LS and LP. The mean LS and the mean LP of F1 generation indicated considerable dominance for resistance in both parameters. The estimates of broad‐sense and narrow‐sense heritability were moderate for LS and LP (0.21—0.55). Narrow‐sense heritability for DS was high (0.77). Estimates of the number of genes controlling each of the parameters (LS, LP, DS) were between 2.5—3.2. It is suggested that the resistance is controlled by three to four quantitative genes with a partial dominance of the alleles for resistance. Indications for genie interaction were found in LS and in LP. A model of inheritance containing complementation between dominant resistance‐alleles is suggested. Highly resistant Ae. longissima accessions are recommended as sources of germplasm for improving the resistance of cultivated wheats to Septoria glume blotch. The possibility of using dominant alleles for resistance in hybrid cultivars is discussed.