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Abstract: In roses, bending of the peduncle during flower development – “bent peduncle phenomenon” (BPP) – results in the production of a series of developmental aberrancies. Detailed characterization of BPP revealed that the typical bending is intrinsically related to developmental features, i.e., the presence of an enlarged sepal appearing as a phylloid structure, floral organ conversions, fasciation of the stem and the higher incidence of BPP in axillary stems developing from BPP stems than from normal stems. The sclerenchymal tissue of BPP stems exhibited larger cells and thinner cell walls than those of normal stems, which may facilitate the bending process. BPP-like bending could be induced by external auxin application and inhibited by auxin transport inhibitors. Thus, in BPP auxin appears to be involved in differential growth, thereby inducing bending. However, there were no differences in endogenous IAA content between the upper and lower sides of bent peduncles, indicating that the asymmetric IAA distribution may be transient. This study strongly suggests that BPP is a developmental process, occurring during the meristematic stage of flower formation, possibly involving auxin distribution, which affects stem bending and fasciation. [Copyright &y& Elsevier]

Abstract: Protocols for in vitro regeneration and production of in vitro-propagated plants and a transformation system were developed for Mirabilis jalapa (Nyctaginaceae). Among the types of explants and the different media tested, consistent shoot regeneration was obtained only from nodal segments grown in a regeneration medium consisting of Murshashige and Skoog medium supplemented with 2mgl−1 6-benzyladenine, 2mgl−1 zeatin and 1mgl−1 indole acetic acid. Regeneration efficiency was dependent on the type of plant – white or pink flowers – used as the source of explants. Stable transformation was obtained following inoculation of nodal segments with Agrobacterium tumefasciens strain EHA105, which harbours the binary plasmid pAD1339 containing both nptII and gus genes under the control of the 35S promoter. Transformation was confirmed by PCR and Southern blot analysis of genomic DNA from mature regenerated plants. β-Glucuronidase (GUS) activity was observed only in tissues regenerated from in vitro-grown plants and not in tissues originating from greenhouse-grown plants. GUS expression was not uniform in regenerated leaves and showed a chimera pattern. [Copyright &y& Elsevier]

Floral transition was studied in lisianthus [Eustoma grandiflorum (Raf.) Shinn.] plants grown in a greenhouse at two planting times (winter and summer) under two photoperiod regimes: long day (LD) and short day (SD), 16 h/8 h and 8 h/16 h (light/dark), respectively. Morphological analyses of the flower meristem of the lisianthus cultivar ‘Heidi Deep Blue’ revealed three distinct stages of development: (1) sepal primordia, (2) petal and stamen primordia (almost simultaneously), and (3) carpel primordia. The appearance of sepal primordia was taken to mark the floral transition stage. Floral transition was hastened in summer-grown plants and under LD treatment, as expressed by a reduction in both the number of nodes and the time from planting. Stem length from base of plant to floral meristem, as measured at floral transition, was similar in all treatments, regardless of the number of nodes produced. At both planting dates, SD induced a higher number of flowers per inflorescence than LD. This report thus describes the direct effect of environmental factors on floral transition in lisianthus. [Copyright &y& Elsevier]

In Lilium longiflorum , vernalization is both an obligatory requirement and the major factor affecting flowering time, however, little is known about the molecular regulation of this mechanism in Lilium and other flowering bulbs. Exposure of L. longiflorum bulbs to 9 weeks at 4 °C greatly promoted stem elongation within the bulb, floral transition and flowering. Subtraction libraries of vernalized (V) and non-vernalized (NV) bulb meristems were constructed. 671 and 479 genes were sequenced, from which 72 and 82 proteins were inferred for the NV–V and the V–NV libraries, respectively. Much lower transcription levels and putative gene functions were recorded in the NV–V libraries compared the V–NV libraries. However, a large number of genes annotated to transposable elements (TEs), represented more than 20% of the sequenced cDNA were expressed in the NV–V libraries, as opposed to less than 2% in the V–NV libraries. The expression profile of several genes potentially involved in the vernalization pathway was assessed. Expression of LlSOC1 , the lily homologue of SUPPRESSOR OF OVER-EXPRESSION OF CO1 ( SOC1 ), an important flowering gene in several plant species, found in the V–NV library, was highly up-regulated during bulb meristem cold exposure. The subtraction libraries provided a fast tool for relevant gene isolation. [ABSTRACT FROM AUTHOR]

Abstract: Crude ethanol extracts from Ficus benjamina leaves strongly inhibit Herpes Simplex Virus 1 and 2 (HSV-1/2) as well as Varicella Zoster Virus (VZV) cell infection in vitro. Bioassay-guided fractionation of the crude extract demonstrated that the most efficient inhibition of HSV-1 and HSV-2 was obtained with the flavonoid fraction. The present study was aimed to further isolate, purify and identify substances with potent antiviral activity from the flavonoid fraction of F. benjamina extracts. Flavonoids were collected from the leaf ethanol extracts through repeated purification procedure and HPLC analysis. The antiviral activity of each substance was then evaluated in cell culture. Three known flavone glycosides, (1) quercetin 3-O-rutinoside, (2) kaempferol 3-O-rutinoside and (3) kaempferol 3-O-robinobioside, showing highest antiviral efficiency were selected and their structure was determined by spectroscopic analyses including NMR and mass spectrometry (MS). These three flavones were highly effective against HSV-1 reaching a selectivity index (SI) of 266, 100 and 666 for compound 1, 2 and 3, respectively, while the SI of their aglycons, quercetin and kaempferol amounted only in 7.1 and 3.2, respectively. Kaempferol 3-O-robinobioside showed similar SI to that of acyclovir (ACV), the standard anti-HSV drug. Although highly effective against HSV-1 and HSV-2, these flavone glycosides did not show any significant activity against VZV. [Copyright &y& Elsevier]

Abstract: Lisianthus (Eustoma grandiflorum) is an ornamental plant with beautiful but scentless flowers. In an attempt to induce a fragrance in their flowers, lisianthus plants were transformed with the Clarkia breweri gene coding for benzyl alcohol acetyltransferase (BEAT), catalyzing the synthesis of the volatile compound benzyl acetate under the regulation of the CaMV35S promoter. An external supply of benzyl alcohol induced five to seven times higher production of benzyl acetate in detached flowers and leaves of transgenic lisianthus plants, compared to non-transformed plants. No benzyl acetate was detected in tissues of both control and transgenic plants fed with water. When fed with additional alcoholic compounds, i.e. hexanol, benzyl alcohol, isoamyl alcohol, phenethyl alcohol, and cinnamyl alcohol, assumed to be used as substrates by BEAT, transgenic in vitro-grown lisianthus plantlets produced significantly higher levels of acetates than control plants. These results demonstrate the possibility of producing substrate-dependent acetates in transgenic lisianthus plants, which could lead to induction of new aromas. [Copyright &y& Elsevier]

• Vernalization is a major pathway regulating flowering time in L. candidum. • Cold exposure at different seasons induces either flowering enhancement or delay. • The effect of cold exposure on flowering is determined by the meristem's developmental stage. Madonna lily (Lilium candidum) is a flowering geophyte growing wild in Israel and in the neighboring region. In view of its holly character in the Christian culture, L. candidum has a great commercial potential as an ornamental crop. However, knowledge regarding its cultivation and the control of its flowering time is very limited. In this study, we aimed to define external factors affecting L. candidum flowering and characterized the developmental stages of the shoot apical meristem (SAM), under different temperature and photoperiod regimes. We found that in most cases, bulb or plant exposure to low temperature (4 °C, forcing) hastened floral transition and flowering in a quantitative manner, whereas day length had a negligible effect on these traits. These results suggest that vernalization is a major pathway regulating flowering time in L. candidum. We also characterized a novel phenomenon in which exposure of the bulb to low temperature led to a delay in bolting and flowering until the following season. We showed that the ability of a bulb to perceive cold exposure as signal for flowering hastening or as a delay was dependent on the SAM's developmental stage and was related to the season. During the summer, cold exposure applied to the SAM at the juvenile phase results in growth inhibition, while from the fall onward, when the meristem has reached its vegetative adult phase, cold exposure promotes bolting and flowering, according to the classic vernalization response. Exposure of the juvenile bulb to 12 °C promotes the transition of the SAM from juvenile to vegetative adult. In conclusion, we showed cold exposure of bulbs at the juvenile phase induced the inhibition of the bolting and flowering, while bulb cold exposure of bulbs at the vegetative adult stage promoted flowering. This study sheds light on the development and flowering physiology of L. candidum and can have applied outcomes for its cultivation as a cut flower crop. [ABSTRACT FROM AUTHOR]

In deciduous fruit trees, the effect of chilling on flowering has mostly been investigated in the “indirect flowering” group, characterized by a period of rest between flower bud formation and blooming. In the present study, we explored the effects of chilling and chilling deprivation on the flowering of Ziziphus jujuba , a temperate deciduous fruit tree belonging to the “direct flowering” group, in which flower bud differentiation, blooming and fruit development occur after dormancy release, during a single growing season. Dormancy release, vegetative growth and flowering time in Z. jujuba cv. Ben-Li were assessed following several treatments of chilling. Chilling treatments quantitatively decreased the timing of vegetative bud dormancy release, thereby accelerating flowering, but had no effect on the time from dormancy release to flowering. Trees grown at a constant temperature of 25 °C, without chilling, broke dormancy and flowered, indicating the facultative character of chilling in this species. We measured the expression of Z. jujuba LFY and AP1 homologues ( ZjLFY and ZjAP1 ). Chilling decreased ZjLFY expression in dormant vegetative buds but had no effect on ZjAP1 expression, which reached peak expression before dormancy release and at anthesis. In conclusion, chilling is not obligatory for dormancy release of Z . jujuba cv. Ben-Li vegetative buds. However, the exposure to chilling during dormancy does accelerate vegetative bud dormancy release and flowering. [ABSTRACT FROM AUTHOR]

Abstract: The effects of shading on lisianthus (Eustoma grandiflorum) floral transition, plant development, flower yield and quality, and content of starch and soluble sugars were assessed in three cultivars, over two consecutive years. Shading nets affording 67% or 88% reduction in light intensity, were fitted at planting in the greenhouse for periods ranging from 3 to 8 weeks. Meristem morphology at floral transition was characterized by apical meristem widening and the appearance of two bract primordia. Floral transition time was affected by cultivars, but in general, longer and heavier shade treatments delayed floral transition; the longest delay (6 weeks) being recorded in Mariachi White under 88% shade for 7 weeks or under a combined shade treatment of 88% for 3 weeks followed by 67% for 5 weeks. Despite interactions between cultivar and shade treatment, consistent trends were discerned: the heaviest and most prolonged shading reduced yield (up to 40%), cut stem length (up to 15%), and number of flower buds/stem (up to 26%), within cultivar. Total carbohydrates levels were very low, and it is questionable whether changes observed in carbohydrate quantity following shade treatments had any effect on plant growth or flower yield. Rather, it appears that lisianthus is very dependent on current photosynthesis, so that even a brief shading interlude could reduce branching and flower quality. It may be concluded that the intensive shading usually applied is detrimental for lisianthus. [Copyright &y& Elsevier]