Cultivar and anatomical analysis of corolla enlargement of petunia (Petunia hybrida Vilm.) by cytokinin application

We found that the corolla of petunia (Petunia hybrida Vilm.) could be conspicuously enlarged by the separate application of three cytokinins: forchlorfenuron (CPPU), N⁶-benzylaminopurine (BA), and zeatin. To obtain the same enlargement as that achieved by CPPU, approximately 30 and 900 times the concentration of BA and zeatin, respectively, were required. CPPU at 3.2 μmol/L increased the limb area of the corollas of 15 cultivars to between 1.3 and 2.4 times (1.8 times on average) the size of the control area. The increase was negatively correlated (R = 0.58) with the “genetic” limb area (i.e., that of the untreated plant). The enlargement of the corolla caused by cytokinin application was mainly attributed to an increase in cell number in most cultivars. This increase resulted from a high rate of cell proliferation and from prolongation of the cell proliferation phase during corolla development. This anatomical change caused by cytokinin application was similar to the anatomical difference among cultivars because genetic differences in limb area resulted mainly from differences in cell number.     

Light quality of continuous illuminating at night to induce floral initiation of Fragaria chiloensis L. CHI-24-1

A wild strawberry strain, Fragaria chiloensis CHI-24-1, produced inflorescences from both parent and asexually propagated daughter plants linked with runners when grown at 23 °C/20 °C (day/night) under a 24 h day-length (DL) of daylight plus nightly lighting by an incandescent lamp, but not under 8 or 16 h DLs. In the present study, the effect of light quality for continuous illuminating at night on floral initiation of CHI-24-1 plants grown under a 24 h DL was examined. The CHI-24-1 plants were grown under a 24 h DL consisting of natural daylight and continuous lighting at night by an incandescent, a blue fluorescent, a red fluorescent or a far-red fluorescent lamp for 40 days in summer and autumn. Also, the CHI-24-1 plants were grown for 40 days in a growth chamber at 25 °C/20 °C (day/night) with natural daylight and continuous lighting at night by red- and four types of far-red light-emitting-diodes (LEDs with peak wavelengths of 660, 700, 735, 780 and 830 nm). In both experiments, floral initiation of the parent and daughter plants was observed under a stereomicroscope. Although more than 50% of the parent and daughter plants initiated flower buds under the incandescent and far-red fluorescent lamps, about 15% and 0% of those initiated flower buds under blue and red fluorescent lamps, respectively. Floral initiation of the parent and daughter plants occurred under the far-red LED light source whose peak wavelength was 735 nm, but not under the red or the other far-red LEDs. From these results, it can be concluded that the effective light wavelength range of nightly continuous illuminating for floral induction in the CHI-24-1 plants is 735 nm in the far-red light region. Hence, the induction of floral initiation by nightly continuous far-red light (735 nm) appeared to be a response mediated by phytochrome.     

Comparison of floral ontogeny in wild-type and double-flowered phenotypes of Syringa vulgaris L. (Oleaceae)

A comparative study of floral ontogeny in normal and double-flowered phenotype of Syringa vulgaris was conducted using the epi-illumination light microscopy. In the wild phenotype, floral differentiation starts with calyx inception and the formation of four sepals in orthogonal positions (two median and two lateral). The corolla emerges as a continuous ring-like structure leading to the appearance of four petal lobes alternating with the sepals. Androecium was formed by initiation of two stamen primordia in transverse plane and finally the bicarpellate gynoecium emerges in median position. In the case of the double-flowered lilac, there are supernumerary petals in an additional whorl. In double-flowered phenotype, a ring meristem is formed acropetally after the first petal whorl initiates. Stamens and carpels initiated similarly in double-flowered as well as in wild-type plants. However, position of stamens deviates from the typical transverse situation. It seems that the appearing of an extra petal whorl did not exhibit any adverse effect on the initiation of other whorls, in terms of organ identity. Therefore, it would be suggested that the double-flowered phenotype of Syringa represents a case of neoheterotopy, with formation of an extra petal whorl, rather than a case of homoheterotopy with transformation of an ancestral androecium whorl into petals.     

Rose (Rosa hybrida L.) EST-derived microsatellite markers and their transferability to strawberry (Fragaria spp.)

The ‘Genome database for Rosaceae (GDR)’ provides a large collection of expressed sequence tags (ESTs) harboring simple sequence repeats (SSRs) from several Rosaceae genera, including Rosa (rose). Primer pairs flanking SSR were designed for 312 unique Rosa ESTs based on GDR database. Eight rose (Rosa hybrida L.) genotypes were tested for PCR amplification, and 287 (92%) of the primer pairs generated allele-specific PCR bands that were readily scored. From 183 (63.7%) primer pairs that evidenced polymorphic alleles among the eight rose cultivars, 20 pairs evidencing EST sequence homology to known gene functions and high levels of polymorphism were selected and utilized for DNA fingerprinting and genetic diversity assessments of 47 rose hybrids. A total of 202 polymorphic bands were scored and generated unique fingerprints for each rose hybrid. The Nei–Li genetic similarity coefficients among 1081 pair-wise comparisons of 47 cultivars exhibited a broad range of genetic variations from 0.30 (‘Grand King’ and ‘Carnival’) to 0.99 (‘First Red’ and ‘Red Champ’). UPGMA cluster analysis divided 47 hybrids into five major groups and two sub-groups. The cross-species transferability of 273 EST-SSR primer pairs was evaluated using four genotypes of the strawberry, a genus member of the Rosaceae family. PCRs on the DNA samples of strawberry were successful for 165 primer pairs; among these, 123 pairs amplified 243 polymorphic bands. As surrogates of the marker transfer, the phenetic relationship among the four strawberry genotypes was evaluated. Genetic similarity coefficients varied from 0.78 (‘Maehyang’ and ‘Janghyee’) to 0.64 (‘Janghyee’ and ‘Pragana’). The results of cluster analysis showed that the three octaploid strawberry cultivars were quite similar, whereas the diploid ‘Pragana’ was related distantly at the genomic DNA level. The EST-SSR markers developed in the present study can be efficiently utilized for genetic diversity studies in Rosaceae.     

Artificial decrease of leaf area affects inflorescence quality but not floral size in Antirrhinum majus

We have studied the effect of artificial modification of leaf area on inflorescence and floral quality in Antirrhinum majus. We used two treatments where we clipped all the leaves except the first three pairs of true leaves, or we cut every leaf visible by the time the plant had six leaf pairs. Decreased leaf area caused a decrease in stem elongation that could be traced back to a decrease in internode elongation. Leaves left on the plant increased their size beyond control. Inflorescence quality was strongly affected since total floral number showed a strong decrease with reduced leaf area. In contrast, floral size hardly changed. Breeding programs in Antirrhinum should take into account growth conditions affecting leaf area when searching for changes in inflorescence quality while floral size can be screened independently of this factor.     

Identification of S-alleles in pear (Pyrus communis L.) cv. ‘Rocha’ and other European cultivars

In this work we report the cloning and identification of S-RNase alleles responsible for gametophytic self-incompatibility (GSI) of ‘Rocha’ pear and of 13 other European pear cultivars that might be used as its pollinators. Partial sequences of S-RNase alleles were amplified by PCR with specific primers hybridising in conserved regions of previously identified S-RNase alleles of Pyrus communis, cloned and sequenced and the S-genotype of eight pear cultivars was fully determined. Three cultivars (‘General Léclerc’ (SqSl), ‘Tosca’ (SbSl) and ‘Alexandrine Douillard’ (SbSk)) shared no S-alleles with ‘Rocha’ (SaSe) and shall be totally compatible with this cultivar. None of the cultivars analysed showed an identical amplification pattern to the one observed in ‘Rocha’, so the other cultivars shall be at least semi-compatible. One new allele was identified in P. communis cv. ‘Beurré d’Avril’ (designated as St). The determination of both S-RNase alleles of cvs ‘Rocha’, ‘Beurré Precoce Morettini’ (SeSk) and ‘Tosca’ and the identification of one S-RNase allele in cvs ‘Carapinheira’ (Sb), ‘Amêndoa’ (Se), ‘Pérola’ (Sk) and ‘Beurré d’Avril’ (St) are important contributions for the effort recently developed worldwide to establish groups of sexual compatibility among European pears.     

Current status of commercial Calibrachoa cultivars as assessed by morphology and other traits

To study the morphological diversity of the popular ornamental crop Calibrachoa, traded since the 1990s, floral and vegetative characters of 91 commercial cultivars were compared to those of natural species. Floral colours were classified according to the ISCC-NBS system and the CIE LAB system. The numerical data obtained by measuring 19 floral and vegetative characters was tested with principal component (PC) analysis. Floral colour classes of commercial cultivars were divided into 37 groups according the ISCC-NBS system, whereas those of natural species were divided into 9 groups. These tendencies were readily observable in the scatter diagrams of the a* vs. b* values and the C* vs. L* values. As the result of PC analysis, six PCs were obtained. For PC4, which negatively correlated with the degree of nocturnal corolla limb closure, the majority of natural species showed negative scores whereas the majority of cultivars had positive PC4 scores. In terms of PC2 (flower size), PC3 (growth form), PC5 (floral shape) and PC6 (leaf shape), natural species were dispersed in a range wider than the cultivars. These results suggest that Calibrachoa cultivars possess more highly variable floral colour than natural species, and breeding programmes to diversify the floral colour seem to have progressed rapidly. The tendency of natural species to close the corolla limb toward evening has been removed almost completely from the cultivars. The floral size, growth form, floral shape and leaf shape of the cultivars were rather uniform compared to those of natural species.     

Syrian pear (Pyrus syriaca) as a pollinator for European pear (Pyrus communis) cultivars

In Israel four European pear cultivars are grown: ‘Spadona’ is the main cultivar and ‘Coscia’, ‘Gentile’ and ‘Spadochina’ are its pollinators. However, molecular S-genotyping revealed that ‘Spadona’ is semi-compatible with its three pollinators. This explains, at least in part, the relatively low pear yield in Israel. The Syrian pear (Pyrus syriaca) grows wild in Israel and blooms intensively, overlapping the blooming of the cultivated European pears. Cross-fertilization between Syrian pear and ‘Spadona’ was shown to be efficient suggesting that Syrian pear might be a potent pollinator for ‘Spadona’. Twenty-six Syrian pear seedlings, from different sites in north-east Israel were S-genotyped identifying 11 that are fully compatible with the four European pear varieties cultivated in Israel. By this screening, 24 different S-RNases were cloned; ten of them are new, whereas the other fourteen had been identified previously. In addition, seedlings of two wild pear species were also S-genotyped. Two seedlings from Pyrus betulifolia and one from Pyrus korshinskii were found to be genetically compatible with the four European pear cultivars. From these seedlings four S-RNases were cloned, two are new, one had been cloned previously and one was identical to an S-RNase allele cloned from Syrian pear in this work.     

Piriformospora indica promotes adventitious root formation in cuttings

Adventitious root formation in excised plant shoots is a crucial process in the vegetative propagation of many plant species, and insufficient rooting causes substantial losses in the propagation industry. Based on the various physiological effects on whole plants described for the basidiomycete Piriformospora indica, it was hypothesized that inoculation of the substrate with this endophyte should promote the generation and growth of adventitious roots in cuttings. Inoculation experiments were conducted to study the effects of P. indica on adventitious rooting in three plant species. Inoculation with P. indica dramatically enhanced the number and length of the adventitious roots in pelargonium and poinsettia. Root colonization parameters suggest that the interaction between the endophyte and cuttings had already occurred before physical contact. In contrast, petunia showed no rooting response to P. indica inoculation. Very fast root formation in this plant indicates that a minimum time period for the fungus–plant interaction is required for establishment of a promoting effect. P. indica-based biotechnology is proposed as a new tool for improving plant propagation systems of plant species or cultivars with low to moderate capacity of adventitious root formation.     

Application of treated wastewater for cultivation of roses (Rosa hybrida) in soil-less culture

No information is available today concerning the effect of irrigation with secondary treated sewage water on growth, production or quality of roses or other cut flowers. In the present study we investigated the effect of irrigation with treated sewage water on roses cultivated in two soil-less medium, perlite, an inert mineral medium and Choir (coconut fibers), an organic medium of high ion absorption capacity. During 12 months of exposure to the treated water, the visible appearance of the plants, their growth, the quantity and size of the flowering stems and their postharvest performance were not affected by the irrigation treatments. Contents of macroelements in the leaf tissues were unaffected by the irrigation with the secondary treated sewage water. At the same time, Cl contents increased 47% in perlite and 73% in Choir grown plants reaching levels characteristic of exposure to moderate salinity. Mn, Cu and B contents increased as well under cultivation in both perlite and Choir under irrigation with treated sewage water. On the other hand, contents of Fe, Zn, Mo and Al, were similar in all treatments. In all treatments contents of all the examined micro and macroelements were within the range accepted for proper plant function.     

Anthocyanins from flowers of Hippeastrum cultivars

The anthocyanins, cyanidin 3-O-(6″-O-α-rhamnopyranosyl-β-glucopyranoside) (1) and pelargonidin 3-O-(6″-O-α-rhamnopyranosyl-β-glucopyranoside) (2), were isolated from the ornamental flowers of a Ugandan Hippeastrum cultivar by a combination of chromatographic techniques, and their structures were elucidated mainly by the use of homo- and heteronuclear nuclear magnetic resonance spectroscopy and electrospray mass spectrometry. The same anthocyanins were found in six different Hippeastrum cultivars purchased in Norway. However, the absolute amount of the anthocyanins (0.08–1.79 mg/g, fresh weight) and the relative proportions of the individual anthocyanins varied from cultivar to cultivar (13.2–96.5% of 1). The colours of the fresh petals of the three cultivars ‘Red Lion’, ‘Royal Velvet’ and ‘Liberty’ were described by the CIELab coordinates L^* (lightness), C^* (chroma) and h_ab (hue angles). All the cultivars showed hue angles corresponding to scarlet nuances (h_ab = 22–35°), with the highest value in ‘Red Lion’. The most reddish petals (in ‘Royal Velvet’) contained the highest relative proportion of 1. Thus, the in vivo colours of these cultivars seem to be correlated with the relative proportions of individual anthocyanin in the petals.     

Photosynthesis of field-grown Arracacha (Arracacia xanthorriza Bancroft) cultivars in relation to root-yield

There has been limited research on measuring potential differences in leaf gas exchange of Arracacha (Peruvian parsnip, Arracacia xanthorriza Bancroft) cultivars, as affected by different environments, as well as its relation to storage root-yield. The present paper reports field measurements of leaf CO₂ assimilation rates (A) for five contrasting cultivars grown at two different high-altitude locations. Using a design of plots chosen at random with three repetitions, commercial root production was determined in the two locations at different altitude (1580 and 1930 m). Daily leaf gas exchange was repeatedly monitored with a portable open-mode infrared gas analyzer at different times in both locations during the growth cycle. Root-yield, leaf area and dry weight were measured. Significant differences in leaf photosynthetic rate and in specific leaf area (SLA) were observed among cultivars. Cultivars with high SLA, had high CO₂ assimilation. Mean (A_n) and total (A_tot) of CO₂ assimilation and SLA were significantly correlated with storage root-yield across cultivars and locations. The three cultivars with the greatest commercial root production also had the highest maximum values for A and the highest specific leaf area, indicating that these two parameters can be used to select for highly productive cultivars of A. xanthorriza.     

Identification of S-genotypes and novel S-RNase alleles in Japanese apricot cultivars native to China

Information on S-genotypes is essential for designing orchards of Japanese apricot (Prunus mume Sieb. et Zucc.) and for hybridization. However, this information is lacking for most cultivars grown in China. Thus, in this work, the S-genotypes of 24 Japanese apricot cultivars native to China were identified by sequencing the PCR products obtained from allele-specific polymerase chain reaction (AS-PCR). Seventeen S-RNase alleles were amplified, ten of them for the first time. The new S-RNase alleles were submitted to GenBank and denoted them as S¹⁷, S¹⁸, S¹⁹, S²⁰, S²¹, S²², S²³, S²⁴, S²⁵ and S²⁶. Furthermore, the S-genotypes of four Japanese apricot cultivars were confirmed by field-testing cross-pollination.     

Relationship between the oil and sugar content in olive oil fruits from Moraiolo and Leccino cultivars during ripening

In our previous work (Cherubini et al., 2009), sugar concentration was proposed as an accurate, reproducible index for technological ripening of olive oil fruits. During 2009 crop season, sugar and oil content of olive oil fruits from Moraiolo and Leccino cultivars were measured during ripening. The sugar content of olive oil fruits was determined both by titration and by using a portable refractometer.     

Identification and distribution of S haplotypes in Brassica vegetables from China

The amplification efficiency and identification diversity with gene-specific primers derived from S locus glycoprotein gene (SLG) and S locus receptor kinase gene (SRK) were compared, and the geographical distribution for S haplotypes was investigated by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) in 72 genotypes of 5 Brassica vegetables from China. The amplification efficiency and identification diversity with class I SRK primers were generally higher than that with class I SLG in most crops tested. Class I alleles were found in total 66 genotypes and they were classified into 16, 10, 7 and 10 groups for Chinese cabbage, purple flowering stalk, cauliflower and cabbage respectively. The number of amplification accessions and identification diversity using the primers of class II SLG and SRK were quite similar. Class II alleles were detected in 55 genotypes and further grouped into one type in mustard and three in other crops. The nucleotide sequences showed high similarity between identical S haplotypes determined by reciprocal pollination and PCR-RFLP tests. It demonstrated that the PCR-RFLP analysis was feasible for identification of S alleles, and SRK should be considered as a better marker for the identification of S haplotypes than SLG. The types of S haplotypes are highly diverse in Brassica vegetables from China. Nevertheless, they were geographically limited in some Brassica vegetables, so the exchange of germplasm resources should be enhanced for breeding.     

Genetic diversity of Rehmannia glutinosa cultivars based on sequence-related amplified polymorphism markers

SRAP analytic system was used to assess genetic diversity of Rehmnnia glutinosa. Twenty-three Rehmnnia glutinosa cultivars were screened with 288 primer combinations, of which 13 produced stable and reproducible amplification patterns in three repetitive experiments. Among a total of 338 amplified fragments, 306 (90.5%) were polymorphic, with an average of 23.5 fragments for each primer combination. The percentage of polymorphic bands for each primer combination varied from 58.3 to 100%. The cultivars had a similarity ranging from 0.335 to 0.713 with a mean of 0.518. Shannon's diversity index and expected heterozygosity were 0.3217 and 0.2008, respectively. Based on the cluster, which were conducted on the similarity matrix of SRAP marker data, the cultivars were divided into four groups at the 20 rescaled distance cluster combine. The results demonstrated that SRAP is a stable marker technique for the assessment of genetic diversity of Rehmannia glutinosa cultivars, and that the level of genetic diversity among them from different production areas was relatively high.     

Chemical compositions and insecticidal effects of essential oils isolated from Achillea gypsicola, Satureja hortensis, Origanum acutidens and Hypericum scabrum against broadbean weevil (Bruchus dentipes)

The essential oils of aerial parts of Achillea gypsicola Hub.-Mor., Hypericum scabrum L., Satureja hortensis L., and Origanum acutidens (Hand.-Mazz.) Letswaart were analyzed in this study by GC and GC–MS and their oils were tested for toxicity against broadbean weevil (Bruchus dentipes). A. gypsicola oil contained camphor (40.17%), 1,8-cineole (22.01%), piperitone (11.29%), borneol (9.50%) and α-terpineol (1.56%) as major components. A total of 74 components were identified by GC–MS in H. scabrum oil, including α-pinene (9.26%), terpinen-4-ol (5.12%), camphor (5.94%), δ-cadinene (4.52%), pulegone (4.45%), γ-muurolene (4.12%), pinocarvone (3.97%) and β-caryophyllene (3.42%) as predominant components. The essential oils of O. acutidens and S. hortensis were characterized by high contents of carvacrol (86.99% and 55.74%), γ-terpinene (0.71% and 20.94%), p-cymene (1.95% and 12.30%), α-terpinene (0.13% and 2.04%) and β-caryophyllene (1.30% and 1.08%). All of the essential oils were toxic to adults of B. dentipes and insect mortality increased with increasing concentration of each oil. The oils (20 μl dose) brought about 100% mortality in 36 h. Although desirable insecticidal activities against the pest were achieved with the oils from all four plant species, S. hortensis and O. acutidens oils were more effective, particularly after 6 h of treatment. The current results concluded that the essential oils, in particular O. acutidens and S. hortensis oils, may be used as potential botanical insecticides against B. dentipes.     

African spider flower (Cleome gynandra L./Gynandropsis gynandra (L.) Briq.) as a red spider mite (Tetranychus urticae Koch) repellent in cut-flower rose (Rosa hybrida L.) cultivation

Companion planting of Cleome gynandra, of Kenyan origin, in beds of cut-flower roses reduces significantly red spider mite (Tetranychus urticae Koch) infestation without any detrimental effect on productivity or flower quality. The level of reduction is dependent upon the density of the C. gynandra plants with 15 plants in a 1.8 m² bed (8.3 plants m²) being the most effective, planted either around the bed perimeter or within the rows of roses. The relatively high density of C. gynandra plants required may limit the direct application of this technology in export-focused, greenhouse rose production yet may be of significant value as a supplement to other mite-control strategies. The potential benefits of such companion planting for growers of field roses and those involved in some domestic markets are also evident. Research into the nature and extraction of the active, volatile mite-repellant components of C. gynandra is indicated.