Inflorescence Stalks Research Articles

The Mechanism of Boron Mobility in Wheat and Canola Phloem

Low-molecular-weight borate complexes were isolated from canola (Brassica napus) and wheat (Triticum aestivum) phloem exudates, as well as the cytoplasm of the fresh-water alga Chara corallina, and identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Phloem exudate was collected from field-grown canola inflorescence stalks by shallow incision, while wheat phloem exudate was collected by aphid stylectomy. Chara cytoplasm was collected by careful manual separation of the cell wall, vacuole, and cytosolic compartments. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry showed the presence of isotopic borate complexes, at mass-to-charge ratio of 690.22/691.22 in the canola and wheat phloem and at 300.11/301.11 in canola phloem and Chara cytoplasm. Using reference compounds, the borate complexes with mass-to-charge ratio 690.22/691.22 was identified as a bis-sucrose (Suc) borate complex in which the 4,6-hydroxyl pairs from the two alpha-glucopyranoside moieties formed an [L(2)B](-1) complex. Further investigation using liquid chromatography electrospray ionization triple quadrupole mass spectrometry analysis confirmed the presence of the bis-Suc borate complex in wheat phloem with a concentration up to 220 microm. The 300.11/301.11 complex was putatively identified as a bis-N-acetyl-serine borate complex but its concentration was below the detection limits of the liquid chromatography electrospray ionization triple quadrupole mass spectrometer so could not be quantified. The presence of borate complexes in the phloem provides a mechanistic explanation for the observed phloem boron mobility in canola and wheat and other species that transport Suc as their primary photoassimilate.

Effects of Herbivory and Inflorescence Size on Insect Visitation to Eryngium yuccifolium (Apiaceae) a Prairie Plant

Herbivory and inflorescence size can influence floral visitors. Damaged inflorescences have been shown to have fewer floral visitors due to changes in floral appearance/chemistry, whereas larger inflorescences attract more pollinators because of greater pollen/nectar reward. This study examined whether floral herbivory by a moth, Coleotechnites eryngiella Bottimer (Gelechiidae), and inflorescence size have any effect on the attractiveness of Eryngium yuccifolium Michaux (Apiaceae) to floral visitors. In particular, the study seeks to determine how combined effects of inflorescence size and herbivory affect overall and main composition of floral visitors groups. Twelve plants, six with one inflorescence stalk (three with and three without herbivory) and six with three inflorescence stalks (three with and three without herbivory) were observed for floral visitors in 2004 and 2007 at four remnant tallgrass prairies located in east-central Illinois, USA. Damaged inflorescences had lower flower visitation than undamaged inflorescences. Larger floral displays attracted more floral visitors. Differences between the numbers of flies, bees and beetles visiting the flowers were not independent of herbivory and inflorescence size. This study provides additional evidence that herbivory and inflorescence size can influence insect visitation. In addition, this study provides further support to recent publications regarding the more sophisticated nature of the pollinator guild associated with members of Apiaceae. Finally, it also provides the foundation for future studies to determine how differences in the composition of floral visitors are associated with the male and female inflorescence phases of E. yuccifolium and their relation to male and female fitness.

Nitrate reductase activity (NRA) in Asphodelus aestivus Brot. (Liliaceae): distribution among organs, seasonal variation and differences among populations

Nitrate reductase activity (NRA) in different compartments (leaves, inflorescence stalks, flowers and tuberous roots) of Asphodelus aestivus Brot. (Liliaceae) and actual mineral nitrogen (NO 3 −-N and NH 4 +-N) in soil surrounding the roots were investigated over one year. Although the highest NRA was found in the leaves, the other plant compartments, such as flowers and tuberous roots, also have nitrate assimilation capacity. High nitrate assimilation capacity under suitable conditions is considered to be a good strategy for development and dominance of this species in Mediterranean environments. There was a seasonal variation in nitrate assimilation in leaves and actual NO 3 −-N content of soils. Depending on actual nitrate content of soils, nitrate assimilation increased in winter.

Induction of tetraploids from petiole explants through colchicine treatments in Echinacea purpurea L.

Petiole explants were obtained from in vitro grown diploid (2x = 22) Echinacea purpurea plantlets. Shoots were regenerated by culturing the explants on MS basal medium containing 0.3 mg/L benzyladenine (BA), 0.01 mg/L naphthaleneacetic acid (NAA) and four concentrations (30, 60, 120, and 240 mg/L) of colchicine for 30 days, or 120 mg/L of colchicine for various durations (7, 14, 21, and 28 days). The regenerated shoots were induced to root on MS basal medium with 0.01 mg/L NAA, and then the root-tips of the regenerated shoots were sampled for count of chromosome number. It was found that a treatment duration of >7 days was necessary for induction of tetraploid (4x = 44) shoots, and treatment with 120 mg/L colchicine for 28 days was the most efficient for induction of tetraploids, yielding 23.5% of tetraploids among all the regenerated shoots. Chimeras were observed in almost all the treatments. However, the ratio of tetraploid to diploid cells in a chimeric plant was usually low. In comparison with diploid plants, tetraploid plants in vitro had larger stomata and thicker roots with more root branches, and had prominently shorter inflorescence stalk when mature.

Discovery of Gynoecium Color Polymorphism in an Aquatic Plant

Flower color polymorphism exhibited by natural populations provides an opportunity for understanding the evolutionary mechanisms contributing to the diversity of floral morphology. However, little is known about the color polymorphism of female organs in flowering plants. Here we report gynoecium color polymorphism in Butomus umbellatus (Butomaceae), an emergent, aquatic monocot. Populations from Mishan, northeastern China comprised two morphs; gynoecia are either pink, as observed in other areas, or white. We measured floral traits and female fecundity in the two gynoecium color morphs in the field. There was no significant difference in plant height, pedicel length, and flower size including petal, sepal and gynoecium between the two morphs, but plants with pink gynoecia had wider inflorescence stalks, larger inner whorl anthers and produced more pollen and ovules than those with white gynoecia. Correspondingly, we found that seed production was significantly higher in the pink than in the white morph. This new finding suggested selection against white gynoecia in part because of low fecundity, consistent with the rarity of the white gynoecium morph in this species.

EFFECT OF PROPAGATION METHODS, SPRAY WITH PACLOBUTRAZOL AND MICRONUTRIENT ON GROWTH OF

This study was carried on Dahlia hybrida cv. Edinburgh, to compare two propagation methods, application of paclobutrazol PBZ at 0, 10 and 20 mg/liter and micronutrients at concentrations 0.00, 0.25 and 0.50 g/liter on vegetative growth. The results can be summarized as follows: Plants propagated by cuttings gave best results for flowering time and inflorescence stalk while plants propagated by tuberous roots gave best results of inflorescence number and inflorescence diameter. Plants sprayed with 10, 20 mg/liter PBZ gave best results of flowering time in the second season and inflorescence diameter in first season. Spraying plants with micronutrient at concentration 0.50 g/liter gave best results of inflorescence number and diameter. In general, plants propagated by cuttings treated with any concentrations of PBZ and micronutrients gave best results of flowering time, but the largest number of inflorescences/plant 12.88 obtained when plants propagates by tuberous roots were treated with 20 mg PBZ/liter and 0.50 g/liter micronutrients in first season, but the largest number 6.77 inflorescences/plant obtained in the second season when plants werenot treated with PBZ.

Amylolitic microbes of nira and laru from Timor Island, East Nusa Tenggara

Thirty nine isolates of microorganisms were isolated from the nira (palm sap from inflorescence stalk of Corypha utan Lamk. or Borassus flabellifer L., laru (fermented palm sap) and their ability to produce amylase has been done. The result of screening showed that eight isolates were positive in the starch iodine test, but their amylolitic activities relatively lower. The amylolitic activities show that laru is not potential source of microbial amylases. In liquid media containing 2% soluble starch, three isolates of fungi (LG4, LMS1, and MI-1) produceamylase and reached a maximum activity at 3 days fermentation, with levels 56.31x102 , 46.78x102 and 41.49x102 U/mL (one unit activity is define as micromoles of glucose produce per mL per minute). Two yeast isolates which isolated from laru or kayu laru were showed their ability to ferment the gula aer and produce ethanol, CO2 and some organic acids, it were identified as Pichia anomala. The other bacterial isolates were identified as Bacillus licheniformis BL43, Chromobacterium sp., Lactobacillus sp., Micrococcus roseus (Staphylococcus roseus), and Bacillus coagulans, its show the lower amylase activities.© 2008 Jurusan Biologi FMIPA UNS Surakarta.Key words: palm sap (nira), fermented palm sap (laru), amylase, fermentation, East Nusa Tenggara

Effects of brassinosteroid, auxin, and cytokinin on ethylene production in Arabidopsis thaliana plants

Inflorescence stalks produced the highest amount of ethylene in response to IAA as compared with other plant parts tested. Leaf age had an effect on IAA-induced ethylene with the youngest leaves showing the greatest stimulation. The highest amount of IAA-induced ethylene was produced in the root or inflorescence tip with regions below this producing less. Inflorescence stalks treated with IAA, 2,4-D, or NAA over a range of concentrations exhibited an increase in ethylene production starting at 1 μM with increasingly greater responses up to 100 μM, followed by a plateau at 500 μM and a significant decline at 1000 μM. Both 2,4-D and NAA elicited a greater response than IAA at all concentrations tested in inflorescence stalks. Inflorescence leaves treated with IAA, 2,4-D, or NAA exhibited the same trend as inflorescence stalks. However, they produced significantly less ethylene. Inflorescence stalks and leaves treated with 100 μM IAA exhibited a dramatic increase in ethylene production 2 h following treatment initiation. Inflorescence stalks showed a further increase 4 h following treatment initiation and no further increase at 6 h. However, there was a slight decline between 6 h and 24 h. Inflorescence leaves exhibited similar rates of IAA-induced ethylene between 2 h and 24 h. Light and high temperature caused a decrease in IAA-induced ethylene in both inflorescence stalks and leaves. Three auxin-insensitive mutants were evaluated for their inflorescence's responsiveness to IAA. aux2 did not produce ethylene in response to 100 μM IAA, while axr1-3 and axr1-12 showed reduced levels of IAA-induced ethylene as compared with Columbia wild type. Inflorescences treated with brassinolide alone had no effect on ethylene production. However, when brassinolide was used in combination with IAA there was a dramatic increase in ethylene production above the induction promoted by IAA alone.

MICROPROPAGATION OF EGYPTIAN DATE PALM C.V SELMY THROUGH FLORAL BUDS CULTURE.

The totally closed date palm (Phoenix dactylifera L) female spathe was surface sterilized by sprayed with ethyl alcohol 70 % prior to aseptic conditions transfer, then flamed. To minimize fast oxidative browning, inflorescence stalks were shortened down to 3 cm then immersed in sterilized antioxidant solution containing citric and ascorbic acids 150 mg/L each for 2 hours, prior to culture. Modified MS medium supplemented with NOA (5 mg/L) + NAA (5 mg/L) + 2iP (1 mg/L) + BA (1 mg/L) was superior in explant survival %, callus formation %, creamy callus colour % and subsequently embryogenic callus formation % after 4 months of incubation. The modified medium (3/4 salts strength) supplemented with IBA (0.3 mg/L) and 2iP (0.5 mg/L) was recorded higher percentage values of embryos formation and the highest significant percentage values of number of embryos as well as embryos fresh weight (g) after 6 weeks of incubation. Embryos cultured on the previous medium in addition to putrescine (100 mg/L) obtained significant values of multiplication rate and growth value as well as total soluble protein and PAL activity after 3 weeks of incubation. Individual shootlets cultured on basal MS medium (3/4 salts strength) supplemented with putrescine (100 mg/L) and IBA (0.5 mg/L) achieved the highest significant values of root formation %, number of roots and root length (cm) as well as PAL activity after 2 months of incubation. On the other hand, using of soil culture containing compost and perlite (1:1, v/v) significantly recorded the highest survival percentage, number of leaves/plantlet and leaf length (cm) for plantlets after three months of acclimatization.

Endophytic colonization of Vitis vinifera L. by Burkholderia phytofirmans strain PsJN: from the rhizosphere to inflorescence tissues

The colonization pattern of Vitis vinifera L. by Burkholderia phytofirmans strain PsJN was determined using grapevine fruiting cuttings with emphasis on putative inflorescence colonization under nonsterile conditions. Two-week-old rooted plants harbouring flower bud initials, grown in nonsterile soil, were inoculated with PsJN:gfp2x. Plant colonization was subsequently monitored at various times after inoculation with plate counts and epifluorescence and/or confocal microscopy. Strain PsJN was chronologically detected on the root surfaces, in the endorhiza, inside grape inflorescence stalks, not inside preflower buds and flowers but rather as an endophyte inside young berries. Data demonstrated low endophytic populations of strain PsJN in inflorescence organs, i.e. grape stalks and immature berries with inconsistency among plants for bacterial colonization of inflorescences. Nevertheless, endophytic colonization of inflorescences by strain PsJN was substantial for some plants. Microscopic analysis revealed PsJN as a thriving endophyte in inflorescence organs after the colonization process. Strain PsJN was visualized colonizing the root surface, entering the endorhiza and spreading to grape inflorescence stalks, pedicels and then to immature berries through xylem vessels. In parallel to these observations, a natural microbial communities was also detected on and inside plants, demonstrating the colonization of grapevine by strain PsJN in the presence of other microorganisms.

DENSITY-DEPENDENT SELF-FERTILIZATION AND MALE VERSUS HERMAPHRODITE SIRING SUCCESS IN AN ANDRODIOECIOUS PLANT

Models of mating-system evolution emphasize the importance of frequency-dependent interactions among mating partners. It is also known that outcross siring success and the selfing rate in self-compatible hermaphrodites can be density dependent. Here, we use array experiments to show that the mating system (i.e., the outcrossing rate) and the siring success of morphs with divergent sex allocation strategies are both density dependent and frequency dependent in androdioecious populations of the wind-pollinated, annual plant Mercurialis annua. In particular, the outcrossing rate is a decreasing function of the mean interplant distance, regulated by a negative exponential pollen fall-off curve. Our results indicate that pollen dispersed from a male inflorescence are over 60% more likely to sire outcrossed progeny than equivalent pollen dispersed from hermaphrodites, likely due to the fact that males, but not hermaphrodites, disperse their pollen from erect inflorescence stalks. Because of this difference, and because males of M. annua produce much more pollen than hermaphrodites, the presence of males in the experimental arrays reduced both the selfing rate and the outcross siring success of hermaphrodites. We use our results to infer a density threshold below which males are unable to persist with hermaphrodites but above which they can invade hermaphroditic populations. We discuss our findings in the context of a metapopulation model, in which males can only persist in well-established populations but are excluded from small, sparse populations, for example, in the early stages of colonization.

Somaclonal variation and stability of GUS gene expression in transgenic agapanthus (Agapanthus praecox ssp. orientalis) plants at the flowering stage

Agapanthus (Agapanthus praecox ssp. orientalis), a liliaceous perennial, is cultivated as an ornamental plant because of its beautiful, blue-violet to white flowers. We have previously produced transgenic plants containing the s-glucuronidase (GUS) reporter gene under the control of cauliflower mosaic virus (CaMV) 35S promoter in an experimental strain of Agapanthus via Agrobacterium-mediated genetic transformation. These transgenic plants have been cultivated for 5 yr after transplantation to pots. In the present study, we carried out morphological characterization, and examination of the ploidy level, pollen fertility and stability of GUS gene expression in 12 transgenic plants derived from five independent lines at the flowering stage. Flow cytometry (FCM) analysis indicated that transgenic plants of four lines kept the diploid level, but those of the remaining one line were tetraploid. For all of the 12 transgenic plants, some morphological variations were observed both in vegetative and floral organs such as decreased number of leaves per inflorescence, smaller leaves, shorter inflorescence stalks, decreased number of florets per inflorescence and smaller florets. Pollen fertility of all the transgenic plants was below 5% as determined by acetocarmine staining. All the 12 transgenic plants showed stable expression of the GUS gene in leaves, roots, tepals, pistils, and stamens, as indicated by histochemical GUS assay, fluorometric GUS assay, and/or real-time reverse transcription-polymerase chain reaction (RT-PCR) analysis. No apparent GUS gene silencing was observed in transgenic agapanthus plants even after 5 yr of cultivation.

Heavy-metal-induced ethylene production in Arabidopsis thaliana

Different plant parts varied in copper sulfate (CuSO(4)) and cadmium sulfate (CdSO(4))-induced ethylene production, inflorescences showed the greatest induction, while all other plant parts tested produced significantly less. Leaf age had a dramatic effect on CuSO(4) and CdSO(4)-induced ethylene production with the youngest leaves showing the greatest stimulation and as the age of the leaf increased there was a reduction in their ability to produce ethylene. However, there was no significant difference in CuSO(4), CdSO(4) and wound-induced ethylene production when whole rosettes were taken from plants that were 7, 14 or 21-day-old. The highest amount of CuSO(4) and CdSO(4)-induced ethylene production was produced in the root tip with regions below this producing less. CuSO(4) and CdSO(4)-induced ethylene production was also greatest from the tip of the inflorescence to 2cm below the tip and from this point down there was a reduction in ethylene production. When inflorescence stalks or leaves were treated with CuSO(4) or CdSO(4) over a range of concentrations from 0 to 800microM, there was an increase in ethylene production starting at 50microM with increasingly greater responses up to 400microM. There was no further increase at the 800microM CuSO(4) concentration; however, there was a slight decline with 800microM CdSO(4). Inflorescence stalks or leaves treated with either 400microM CuSO(4) or CdSO(4) exhibited a dramatic increase in ethylene production 2h following treatment initiation and remained high over a 24-h period with a decline in ethylene production after this time in inflorescence stalks but not the leaves. It was found that light caused a dramatic decrease in CuSO(4), CdSO(4) and wound-induced ethylene production in both inflorescence stalks and leaves. When inflorescence stalks or leaves were treated at 43 degrees C, there was a dramatic effect on CuSO(4), CdSO(4) and wound-induced ethylene production in each.

High frequency early in vitro flowering of Dendrobium Madame Thong-In (Orchidaceae)

We have successfully developed a method to induce early in vitro flowering of the self-pollinated seedlings of a tropical orchid hybrid, Dendrobium Madame Thong-In. Transition of vegetative shoot apical meristem to inflorescence meristem was observed when young protocorms were cultured in modified KC liquid medium. In contrast, protocorms cultured on Gelrite-solidified medium only produced axillary shoots and roots. CW was required to trigger the transitional shoot apical meristem and BA enhanced inflorescence stalk initiation and flower bud formation. However, normal flower development was deformed in liquid medium but developed fully upon transferring to two-layered (liquid over Gelrite-solidified) medium. Under optimal condition, in vitro flowering was observed about 5 months after seed sowing. Segregation of flower colours was observed in these seedlings and seedpods formed upon artificial pollination of the in vitro flowers.

The effects of herbivory and resource variability on the production of a second inflorescence by the desert lily, Pancratium sickenbergeri

We investigated the effects of herbivory by the dorcas gazelle, Gazella dorcas, on the production of a second inflorescence in a desert lily, Pancratium sickenbergeri (Amaryllidaceae), after the first inflorescence was eaten. In three populations exposed to different levels of herbivory, we conducted an inflorescence-clipping experiment in the flowering seasons of 1997, 1998 and 1999. The experiment was performed on inflorescences at both the emerging stage and the anthesis stage. Plants in each control group were undamaged. Clipped plants had a greater probability of producing a second inflorescence stalk than unclipped plants. In all the populations, the probability of producing a second inflorescence was greater when the first inflorescence was cut in the emerging stage than when it was cut in anthesis, indicating that there was a cost of compensation. In the population with the highest level of herbivory, the production of a second inflorescence stalk was related to resource availability in all 3 years. Plants produced as many flowers or fruits on the second stalk as on the first, indicating that potential reproductive output is double that usually achieved. Although we found no evidence for a trade-off between investment in first and second inflorescence stalks, the lower probability of producing a second inflorescence if heavy investment had been made in the first inflorescence indicates that compensation is costly. These results contradict the mutualism hypothesis that herbivory is beneficial to plants and provide support for the trade-off hypothesis that benefits of herbivory are proximal and are attained at an evolutionary cost.

Presence of banana xanthomonas wilt (Xanthomonas campestris pv. musacearum) in the Democratic Republic of Congo (DRC)

In May 2004, following reports from local farmers of a devastating new banana disease, the first three authors visited Masisi District, 72 km northwest from Goma in North Kivu Province, Democratic Republic of Congo (DRC) (altitude 1700 m above sea level) and diagnosed banana bacterial wilt caused by Xanthomonas campestris pv. musacearum (Xcm). Symptoms were similar to those seen in Uganda (Tushemereirwe et al., 2003) and included: progressive yellowing, wilting and blackening of leaves; yellow or brown vascular streaks throughout the plant; pockets of pale yellow bacterial ooze in airspaces within leaf bases; premature ripening and internal discoloration of fruits; and shrivelling of male inflorescence buds. Inflorescence symptoms probably result from transmission of bacteria by insects, and were uncommon. This may explain the limited spread in DRC since 2001, only c. 10 km from the original focus at Bashali Mokoto village, compared with 400 km in Uganda over the same period (see www.banana.go.ug). As in Uganda, ABB banana genotypes (especially 'Pisang Awak') appear to be the first to be infected, and matooke clones (Musa AAA-EA group) the last. Affected stools do not always die; new suckers emerge and these initially appear healthy but usually become infected from the mother plant, rarely surviving to flowering stage. The epicentre of the outbreak in Masisi was devastated, with total loss of yield and an alarming impact on food security. Using methods described by Tushemereirwe et al. (2004), yellow pigmented bacteria were isolated as almost pure cultures from samples of diseased inflorescence stalks sent to the Global Plant Clinic at CABI Bioscience, UK. Biochemical and molecular characteristics of two isolates were indistinguishable from Xcm from Uganda. Both caused rapid wilting within 7-10 days of inoculation into young banana plants from which the same organism was reisolated. It may be feasible to eradicate this outbreak by destroying affected plants and cleaning up affected fields, combined with removing male flower buds in surrounding healthy plants to prevent insect transmission. However, the first author has recently observed a new disease focus c. 20 km from the first, so continued vigilance and control action will be needed. The origin of these outbreaks is unknown. Until 2001, Xcm was known only from Ethiopia, where it causes disease in enset (Ensete ventricosum) and cultivated banana (Yirgou and Bradbury, 1968, 1974). It is possible that the disease has spread from wild or semicultivated enset plants, which can be found throughout the Masisi region. (Author's abstract).

Isoflavonoids are present in Arabidopsis thaliana despite the absence of any homologue to known isoflavonoid synthases

Extracts from Arabidopsis thaliana leaves and inflorescence stalks and from Lepidium sativa (Brassicaceae) seedlings were analysed by HPLC-MS-SIM and by five isoflavonoid-specific ELISA methods after the HPLC fractionation of samples, in order to determine presence of isoflavonoids. Individual ELISAs were specific for daidzein, genistein, biochanin A and for their derivatives substituted either at the 4′- or at the 7- positions. Both analytical approaches revealed homologous spectra of isoflavonoids in both plant species. As the ononin specific immunoassay was not available this compound was only detected by HPLC-MS. Formononetin and prunetin represented the main aglycones followed by biochanin A, daidzein and genistein; sissotrin was the most abundant isoflavonoid glycoside followed by ononin, daidzin and genistin. The content of individual compounds ranged from a few micrograms up to 2.2 mg kg –1 (dry weight). Expression profiles of A. thaliana genes homologous to enzymes involved in isoflavonoid synthesis and metabolism were extracted from publicly available transcriptomic datasets for various tissues. Genes likely to be involved in important steps of the isoflavonoid metabolism in A. thaliana were identified. However, in accord with the previously published data, no homologue to isoflavone synthases known from the Fabaceae plants was found. These aryl migrating enzymes belong to the CYP93C family that is absent in A. thaliana. We conclude that another gene must be responsible for biosynthesis of the isoflavone skeleton in Brassicaceae.

Characterization and comparative analysis of Arabidopsis phosphatidylinositol phosphate 5-kinase 10 reveals differences in Arabidopsis and human phosphatidylinositol phosphate kinases

Arabidopsis phosphatidylinositol phosphate (PtdInsP) kinase 10 ( AtPIPK10; At4g01190) is shown to be a functional enzyme of the subfamily A, type I AtPtdInsP kinases. It is biochemically distinct from AtPIPK1 (At1g21980), the only other previously characterized AtPtdInsP kinase which is of the B subfamily. AtPIPK10 has the same K m, but a 10-fold lower V max than AtPIPK1 and it is insensitive to phosphatidic acid. AtPIPK10 transcript is most abundant in inflorescence stalks and flowers, whereas AtPIPK1 transcript is present in all tissues. Comparative analysis of recombinant AtPIPK10 and AtPIPK1 with recombinant HsPIPKIα reveals that the Arabidopsis enzymes have roughly 200- and 20-fold lower V max/ K m, respectively. These data reveal one explanation for the longstanding mystery of the relatively low phosphatidylinositol-(4,5)-bisphosphate:phosphatidylinositol-4-phosphate ratio in terrestrial plants.

Rapid response to habitat restoration by the perennial Primula veris as revealed by demographic monitoring

The demography of Primula veris, a typical species of the species-rich Mesobromion grasslands, was investigated at two contrasting habitats in Eastern Belgium. Both a forested site and a clear-cut parcel were part of formerly larger calcareous grassland areas. By monitoring the demographic response of the target species, this study attempts to clarify the differences in fecundity, growth and survival between a restored and degraded calcareous grassland site. A study of plant traits showed a decrease in number of flowers, inflorescence stalks and plant size under a closing tree canopy. We surveyed individuals in permanent plots between 1999 and 2001. At the forested site, a first sign of decline included lower proportions of flowering individuals and afterwards an increase in mortality was found. Alternatively, removing canopy resulted in an immediate flowering response and both increased growth and seedling recruitment the year after. At both sites, survival rates strongly depended on the initial state, location and year. Projection matrix analysis revealed large differences in modelled population growth rates between sites and years. Under closing canopy the species showed only slow population decline, but the decrease was larger in the last survey year when higher mortality affected the number of reproductive individuals. Transitions between stages with the highest impact on population growth rate were identified by elasticity analysis. If calcareous grassland is forested, survival of reproductive adults is predicted to be very important for conservation of P. veris populations. However, seedling recruitment needs to be raised to guarantee long-term persistence of the populations. On the other hand, clear-felling of a site for restoration of species-rich calcareous grasslands may result in a rapid recovery of certain species.

Herbivory in epiphytic bromeliads, orchids and ferns in a Mexican montane forest

Herbivory is important in tropical woody plants, but the few data available suggest that rates of herbivory are mostly low in epiphytes. We quantified herbivory at the community level in five bromeliad, three orchid and five fern species of a Mexican humid montane forest. Leaf area loss was <1.5% in bromeliads and orchids, but much higher (7–20%) in ferns. Damage was positively correlated with leaf nitrogen content but not with leaf life span. In contrast to low leaf damage, many bromeliads were infested by curculionid larvae feeding on the meristematic tissue at the ramet base, and we estimate that this accounts for 18 and 31% of ramet and shoot death of large individuals of Tillandsia punctulata and T. deppeana, respectively. Herbivory in flowers, capsules or inflorescence stalks reduced fecundity by c. 14–18% in three of the five bromeliads and by 90% in the orchid Lycaste aromatica, but had little effect on the other species. These data show that even if the leaf area consumed is indeed low in epiphytic orchids and bromeliads, the less conspicuous damage done to reproductive organs and meristematic tissue can have a strong effect on fecundity and survival.