Volatile composition, emission pattern, and localization of floral scent emission in Mirabilis jalapa (Nyctaginaceae)

We elucidated scent components, daily emission patterns, and the localization of floral scent release of Mirabilis jalapa. Volatiles emitted by the whole plant as well as by detached flowers were investigated using dynamic headspace analysis and gas chromatography/ mass spectrometry. Among several constituents including (Z)-3-hexenyl acetate, β-myrcene, (Z)-ocimene, and benzyl benzoate, the monoterpene (E)-β-ocimene was the major fragrance component. Fragrance release occurred in a time-dependent manner. The emission of volatiles, including (E)-β-ocimene, showed an evening-specific maximum (1700-2000 pm). The emission of (Z)-3-hexenyl acetate reached its maximum 3 h later. Histological (neutral red staining) and morphological studies (electron and light microscopy) of the flower surface and tissues of M. jalapa revealed differences in surface structures and tissue characteristics. The flower could be divided into four main sections, including the tube, the transition zone between tube and limb, a star-shaped center of the limb, and petaloid lobes of the limb. These petaloid lobes are the site of (E)-β-ocimene release. Stomata and trichomes found on the abaxial flower surface were not directly involved in fragrance release. Clear indications of osmophores involved in scent release could not be found. Thus, the results indicate that floral volatiles probably are released by diffuse emission in M. jalapa.     

紫茉莉4,5-多巴双加氧酶基因的克隆和表达

通过同源克隆的方法分离了紫茉莉的4,5-多巴双加氧酶(4,5-Dopa-dioxygenase)基因的cDNA片段,并对该基因能在紫茉莉花发育的5个时期的表达作分析。结果表明,该基因的cDNA片段长度801bp,与甜菜和太阳花的同源性分别为67%和63%。该基因均可在转录水平表达,但在紫茉莉不同发育时期的表达量有一定差异,随着发育时期的推进其表达量逐渐增强。     

光照强度对紫茉莉生长和镉积累的影响

采用土培实验研究了25mg／kg镉处理下全光照（HL）、50％全光照（ML）和10％全光照（LL）三种生长光强对紫茉莉生长、光合作用和镉积累相关指标的影响,结果表明,紫茉莉对镉具有较高的耐性,ML对紫茉莉的生长最为有利。镉胁迫下紫茉莉净光合速率和最大光化学效率降低,暗呼吸速率增高,生物量减小。特别在高光强条件下。ML植株镉积累量最大,对镉污染土壤的植物修复效果较好。     

Ribosome-inactivating and adenine polynucleotide glycosylase activities in Mirabilis jalapa L. tissues

Several tissues of Mirabilis jalapa L. (Nyctaginaceae) were assayed for inhibition of translation by a rabbit reticulocyte lysate (as a signal of ribosome-inactivating activity) and for adenine DNA glycosylase activity, activities that are both due to the presence of a class of enzymes called ribosome-inactivating proteins (RIPs), currently classified as rRNA N-glycosylases (EC ). These activities were highest in seed; intermediate in flower bud, immature seed, sepal + gynoecium, leaf, and root; and very low in all other tissues. By cation-exchange chromatography, four protein peaks with inhibitory activity on cell-free translation were identified in extracts from seeds, and two proteins were isolated from peaks 1 and 4, all of which have the properties of single-chain type 1 RIP. One is Mirabilis antiviral protein (MAP), so far purified only from roots. The second is a new protein that we propose to call MAP-4. The distribution of MAP and MAP-4 in several tissues was determined with a novel experimental approach based on liquid chromatography/mass spectrometry. The direct enzymatic activity of MAP on several substrates is described here for the first time. MAP depurinated not only rRNA in intact ribosomes, thus inhibiting protein synthesis, but also other polynucleotides such as poly(A), DNA, and tobacco mosaic virus RNA. Autologous DNA was depurinated more extensively than other polynucleotides. Therefore, the enzymatic activity of this protein may be better described as adenine polynucleotide glycosylase activity rather than rRNA N-glycosylase activity. Finally, MAP does not cross-react immunologically with other commonly utilized RIPs.     

The role of gibberellins in embryo axis development

The role of gibberellins (GAs) during early embryo development was examined using microspore-derived embryos (MDEs) of Brassica napus. At the globular stage of development, 10 d after initial culture (DAC) when endogenous GA(1) levels are increasing rapidly, a triazole, uniconazole, was used at 1, 33 and 100 microM to inhibit GA biosynthesis. Within this dose range there was no apparent effect of the inhibitor on embryo growth through to the early torpedo stage. However, by 25 DAC uniconazole-treated MDEs showed significantly reduced (50%) axis elongation. Addition of GA(1) at 33 microM on 14 DAC to embryos pretreated with 1 microM uniconazole on 10 DAC prevented this reduction in axis length, giving axis elongation equivalent to untreated MDEs. Application of GA(1) alone, however, did not significantly increase axis elongation. The reduced axis growth seen with uniconazole treatment was due to reduced cell elongation, but not cell number, and the co-applied GA(1) thus prevented the uniconazole-induced reduction in cell length. The elongating axis of MDEs may thus be a useful tool for examining the role of GAs in cell elongation.     

The role of gibberellins and cytokinins in the growth correlative effect of cotyledons in flax and pea

It is wellknown that following the amputation, or darkening of one cotyledon in decapitated flax seedlings, the opposite remaining, or illuminated, cotyledon exerts a stimulatory effect on the growth of its axillary bud. For the induction of this stimulating effect a 21–72 h continuous darkening of the cotyledon is sufficient. Endogenous gibberellins take part in the stimulation effect of the illuminated cotyledon, since their level in the illuminated cotyledon increases as early as 12–48 h following the darkening of the opposite cotyledon. The apical part of the cotyledon has a higher growth stimulatory effect on the growth of the cotyledonary axillary bud than the basal half. This again is associated with endogenous gibberellins the level of which is higher in the apical half of the cotyledon than in the basal one. Upon removal of the root and hypocotyl base in decapitated flax seedlings deprived of one cotyledon, the remaining cotyledon loses its stimulatory influence, so that the bud of the amputated cotyledon grows more vigorously (Dostál 1955). In this growth correlative phenomenon the root may be substituted by cytokinin BA applied in the form of a 0.1–1.0 per cent paste onto the remaining cotyledon, for again in this case the bud of the preserved cotyledon grows more vigorously. Following the decapitation of the axillary of the amputated cotyledon in decapitated pea seedlings with an intact root and deprived of one cotyledon, the axillary of the remaining cotyledon grows more intensively than the serial of the removed one. If the plants operated on in the same way are deprived of the root, the serial of the removed cotyledon gains a correlative growth predominance. If the plants deprived of root are cultivated at the same time in a solution of BA (10–20 mg 1⁻¹), the correlative predominance is acquired by the axillary of the remaining cotyledon. In growth correlations between cotyledons and their axillary buds in pea seedlings the root may thus be substituted by exogenous cytokinin, as well.     

Number of floral organs in Circaeaster agrestis (Circaeasteraceae) and possible homeosis among floral organs

98.9% of 5092 flowers from 1041 individuals of Circaeaster agrestis have five floral organs, the formula is P₃A₁G₁ (73.13%), P₂A₂G₁ (25.59%), and P₂A₁G₂ (0.22%). Only 0.4% of the flowers have six floral organs and the formula is P₃A₁G₂ (20 flowers) or P₃A₂G₁ (one flower). All these flowers have one vascular bundle in the pedicel and were considered to be normal ones. There are 33 flowers (0.65%) with six or more floral organs and two vascular bundles in the pedicel and we found traces of fusion of different degree of two flowers into one. These flowers were considered as abnormal. Therefore the normal number of floral organs of C. agrestis is five and occasionally six, and the floral formulas are P₃A₁G₁ or P₂A₂G₁, sometimes P₂A₁G₂, and occasionally P₃A₁G₂ or P₃A₂G₁. A tepal in P₃A₁G₁ may be replaced by a stamen in P₂A₂G₁ or by a carpel in P₂A₁G₂ or in reverse. A carpel in P₃A₁G₂ may be replaced by a stamen in P₃A₂G₁ or in reverse. We hypothesize that there are two possibilities for the number of the floral organs to be five (six), the result of reduction from P₃A₂G₂, or there exists homeosis among floral organs.     

Ectopic expression of AINTEGUMENTA in Arabidopsis plants results in increased growth of floral organs.

AINTEGUMENTA (ANT) was previously shown to be involved in floral organ initiation and growth in Arabidopsis. ant flowers have fewer and smaller floral organs and possess ovules that lack integuments and a functional embryo sac. The present work shows that young floral meristems of ant plants are smaller than those in wild type. Failure to initiate the full number of organ primordia in ant flowers may result from insufficient numbers of meristematic cells. The decreased size of ant floral organs appears to be a consequence of decreased cell division within organ primordia. Ectopic expression of ANT under the control of the constitutive 35S promoter results in the development of larger floral organs. The number and shape of these organs is not altered and the size of vegetative organs is normal. Microscopic and molecular analyses indicate that the increased size of 35S::ANT sepals is the result of increased cell division, whereas the increased sizes of 35S::ANT petals, stamens, and carpels are primarily attributable to increased cell expansion. In addition, 35S::ANT ovules often exhibit increased growth of the nucellus and the funiculus. These results suggest that ANT stimulates cell growth in floral organs.     

Arabidopsis thaliana FIMBRIATA PETIOLES gene, controlling cell division and growth in floral organs

A new mutant, fimbriata petioles (fip), of Arabidopsis thaliana was obtained by chemical mutagenesis. The mutant is characterized by unusual anomalies of floral organs. Clusters of very large cells formed in the distal region of sepals and petals, which created fringed edges of these organs. An analysis of the morphology of the floral organs and leaves of the fip as 1 double mutant revealed a complementary interaction of the ASYMMETRIC LEAVES1 (AS1) and FIMBRIATA PETIOLES (FIP) genes. It was assumed that the FIP gene, together with the AS1 gene, controls cell proliferation, preventing their premature entry into endocycle.     

A kinematic analysis of gynoecial growth in Lilium longiflorum: surface growth patterns in all floral organs are triphasic

Sequential marking experiments combined with histological and morphological examination indicate that growth of the gynoecium in Lilium longiflorum Thunb. (Easter lily) is triphasic. Phase I (gynoecia less than 10 mm in length) is characterized by spatial and temporal variation in local relative growth rate and mitotic index throughout the entire gynoecium. In Phase II (10-100 mm), a steady growth peak is restricted to the proximal 5 to 15 mm of the style, while the ovary shows uniform growth. In Phase III (100-135 mm), the ovary ceases growth and the maximal growth zone of the gynoecium migrates from the proximal to the distal end of the style. Comparison of surface growth patterns and differentiation events in the gynoecium to those previously described in the tepal and another demonstrates the triphasic nature of growth in the whole lily flower.     

Distribution of endogenous gibberellins in vegetative and reproductive organs of Brassica

Recognizing the physiological diversity of different plant organs, studies were conducted to investigate the distribution of endogenous gibberellins (GAs) in Brassica (canola or oilseed rape). GA₁ and its biosynthetic precursors, GA₂₀ and GA₁₉, were extracted, chromatographically purified, and quantified by gas-chromatography-selected ion monitoring (GC-SIM), using [²H₂]GAs as internal standards. In young (vegetative) B. napus cv. Westar plants, GA concentrations were lowest in the roots, increased acropetally along the shoot axis, and were highest in the shoot tips. GA concentrations were high but variable in leaves. GA₁ concentrations also increased acropetally along the plant axis in reproductive plants. During early silique filling, GA₁ concentrations were highest in siliques and progressively lower in flowers, inflorescence stalks (peduncles plus pedicels), stem, leaves, and roots. Concentrations of GA₁₉ and GA₂₀ showed similar patterns of distribution except in leaves, in which concentrations were higher, but variable. Immature siliques were qualitatively rich in endogenous GAs and GA₁, GA₃, GA₄, GA₈, GA₉, GA₁₇, GA₁₉, GA₂₀, GA₂₄, GA₂₉, GA₃₄, GA₅₁, and GA₅₃ were identified by GC-SIM. In whole siliques, GA₁₉, GA₂₀, GA₁, and GA₈ concentrations declined during maturation due to declining levels in the maturing seeds; their concentrations in the silique coats remained relatively constant and low. These studies demonstrate that GAs are differentially distributed in _Brassica with a general pattern of acropetally increasing concentration in shoots and high concentration in actively growing and developing organs.     

The effects of pollen load size and donor diversity on pollen performance, selective abortion, and progeny vigor in Mirabilis jalapa

The influence of pollen competitive environment on pollen performance (pollen germination, stigmatic penetration, and pollen tube growth rate), the maturation or abortion of initiated fruit, seed size, and seedling vigor was explored by manipulating the size and diversity of stigmatic pollen loads on Mirabilis jalapa. All aspects of pollen performance significantly increased with the number of pollen grains on a stigma or pollen tubes in a style, but was not influenced by the diversity of pollen donors. Plants tended to mature single-ovulate fruits that came from flowers where pollen load size and diversity were greatest and aborted those where these were lowest. No plants from seeds resulting from pollinations with a single pollen grain survived, but other fitness measures were mostly determined by maternal plant. The data suggest that pollen performance is influenced by pollen competitive environment, and both the genetic diversity of the pollen load and number of competing pollen tubes are important determinants of seed/fruit abortion.     

Changes in endogenous gibberellins in plant organs producing and utilizing photosynthates

The distribution of endogenous gibberellin-like substances in individual organs ofZea mays L., cv. CE 250, plants was investigated during the transition from the vegetative to the generative phase of development. The gradient of the content of gibberellin-like substances and photosynthetic activity in leaf segments was followed in different parts of the Jeaves, as well as the changes in the content of gibberellin-like substances in leaf segments during an exposure in the light and in the dark. The gradient of the content of endogenous gibberellin-liko substances in the leaves, in the stem and in the spike is interpreted in terms of possible relationship of these compounds to the regulation of sink — source.