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1.
Min B. Rayamajhi Thai K. Van Paul D. Pratt Ted D. Center Phillip W. Tipping 《Plant Ecology》2007,192(1):119-132
Melaleuca quinquenervia (melaleuca) is a native of Australia but has become an invasive plant in Florida, USA. We conducted a long-term demographic
study of melaleuca in three sections (central, transitional, and peripheral) of monoculture stands located in Florida, and
quantified absolute density, diameter at breast height and basal area of trees by section at three sites. Additionally, we
monitored the impacts of natural enemy (insects and fungi) on melaleuca populations which became apparent after 2001. Both
absolute density and basal area, from before (1997–2001) and after noticeable natural-enemy impact (2002–2005), were compared.
Prior to the natural-enemy impact, absolute density of melaleuca trees declined primarily due to self-thinning and associated
losses of small trees, but diameter at breast height increased, as did the basal area. Later during the period when natural
enemies prevailed, absolute density declined at a significantly greater rate across all sections but was highest at the periphery.
The decrease in mean absolute density and basal area/ha of melaleuca during the natural-enemy impacted period coincided with
the increased incidence of the populations of plant-feeding insects and fungi. The mean diameter at breast height continued
to increase in all sections of the stands throughout the study period. An increasing trend in basal area prior to natural-enemy
impact was reversed after increase in natural-enemy abundance and noticeable impact in all three sections of the stands. These
findings lend support to a growing body of literature that implicates natural enemies as increasingly important density-independent
regulators of M. quinquenervia populations.
The U.S. Government's right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged 相似文献
2.
Jorge A. Zavala Clare L. Casteel Paul D. Nabity May R. Berenbaum Evan H. DeLucia 《Oecologia》2009,161(1):35-41
Elevated levels of CO2, equivalent to those projected to occur under global climate change scenarios, increase the susceptibility of soybean foliage
to herbivores by down-regulating the expression of genes related to the defense hormones jasmonic acid and ethylene; these
in turn decrease the gene expression and activity of cysteine proteinase inhibitors (CystPIs), the principal antiherbivore
defenses in foliage. To examine the effects of elevated CO2 on the preference of Japanese beetle (JB; Popillia japonica) for leaves of different ages within the plant, soybeans were grown at the SoyFACE facility at the University of Illinois
at Urbana-Champaign. When given a choice, JB consistently inflicted greater levels of damage on older leaves than on younger
leaves, and there was a trend for a greater preference for young leaves grown under elevated CO2 compared to those grown under ambient CO2. More heavily damaged older leaves and those grown under elevated CO2 had reduced CystPI activity, and JB that consumed leaves with lower CystPI activity had correspondingly greater gut proteinase
activity. Younger leaves with higher CystPI activity and photosynthetic rates may contribute disproportionately to plant fitness
and are more protected against herbivore attack than older foliage. Cysteine proteinase inhibitors are potent defenses against
JB, and the effectiveness of this defense is modulated by growth under elevated CO2 as well as leaf position. 相似文献
3.
Kevin J. Delaney 《Plant Ecology》2008,199(2):187-200
Insect herbivory has variable effects on plant physiology; so greater understanding is needed about how injury alters photosynthesis
on individual injured and uninjured leaves. Gas exchange and light-adapted leaf chlorophyll fluorescence measurements were
collected from uninjured and mechanical partial leaf defoliation in two experiments with Nerium oleander (Apocynaceae) leaves, and one experiment with Danaus plexippus herbivory on Asclepias curassavica (Asclepiadaceae) leaves. Gas exchange impairment (lower photosynthetic rate (P
n
), stomatal conductance (g
s)) indicates water stress in a leaf, suggests stomatal limitations causing injury P
n
impairment. The same pattern of gas exchange impairment also occurred on uninjured leaves opposite from injured leaves in
both N. oleander experiments. This is an interesting result because photosynthetic impairment is rarely reported on injured leaves near injured
leaves. No photosynthetic changes occurred in uninjured A. curassavica leaves opposite from D. plexippus-fed leaves. Partially defoliated leaves that had P
n
and g
s reductions lacked any significant changes in intercellular leaf [CO2], C
i. These results neither support, nor are sufficient to reject, stomatal limitations to photosynthesis. Manually imposed midrib
vein severance in N. oleander experiment #1 significantly increased leaf C
i, indicating mesophyll limitations to photosynthesis. Maximal light-adapted leaf photochemical efficiency () and also non-photochemical quenching (q
N) were reduced by mechanical or insect herbivory to both study species, suggesting leaf trouble handling excess light energy
not used for photochemistry. Midrib injury on N. oleander leaves and D. plexippus herbivory on A. curassavica leaves also reduced effective quantum yield (ΦPSII) and photochemical quenching (q
P); so reduced plastoquinone pools could lead to additional PSII reaction center closure. 相似文献
4.
The mechanisms that allow introduced plants to become invasive are poorly understood. Here, we present a test of the evolution
of increased competitive ability hypothesis, which holds that because specialized natural enemies may be absent from the introduced
range, exotic plants may evolve to invest less in anti-herbivore defenses and thereby gain a competitive advantage over native
plants. We grew Solidago gigantea plants derived from both the native range (North America) and the invasive range (Europe) in a common garden in the native
range for 2 years. Half the plants were treated with insecticide to protect them from insect herbivores and the other half
were exposed to insects that colonized the garden from nearby fields. Insect herbivore biomass was significantly higher on
European plants than US plants in the first year but not the second. European plants were more heavily attacked by pathogens
in both years of the study. When exposed to insect herbivores, US plants produced more seed than European plants, but when
plants were protected from herbivores, seed production was equivalent between US plants and European plants. The presence
of insect herbivores suppressed seed production of European plants much more than that of US plants, even though the level
of herbivory experienced by European and US plants was similar in the second year, suggesting that the ability to tolerate
herbivory was diminished in European plants. These results partially support the EICA hypothesis: plants from the introduced
range were more susceptible to some natural enemies and benefited more from insect removal than plants from the native range.
The prediction that European plants would perform better than US plants in the absence of insect herbivores was not supported.
Electronic Supplementary Material Supplementary material is available for this article at 相似文献
5.
Septobasidium parviflorae sp. nov. on Pinus parviflora is described and illustrated. This species is characterized by its whitish-gray, gray to dark gray-colored fungus body with
an indeterminate margin, hyphal strands, and cylindrical basidia with long sterigmata. This is the first report of Septobasidium occurring on a member of the genus Pinus in Japan. 相似文献
6.
R. Ramirez-Malagon I. Aguilar-Ramirez A. Borodanenko L. Perez-Moreno J. L. Barrera-Guerra H. G. Nuñez-Palenius N. Ochoa-Alejo 《In vitro cellular & developmental biology. Plant》2007,43(6):660-665
Mammillaria species are the most numerous within Cactaceae family, and some of them are threatened with extinction as a result of human
activities. In this work, results of in vitro propagation are presented for ten Mammillaria species, testing 20 combinations of indole-3-acetic acid (IAA) and kinetin. Best results on shoot formation were obtained
using kinetin at two levels: 27.9 and 46.5 μM. All IAA levels tested were able to induce de novo shoot formation in M. bocasana, M. densispina, M. hahniana, M. hutchisoniana, M. orcutii, M. pectinifera, M. perbella, M. picta, M. rhodantha, and M. zephyranthoides. Depending on the IAA level tested, four responding groups were observed concerning their highest shoot-formation number.
For all species, the highest average of shoot formation was achieved with 5.7:46.5 or 11.4:46.5 μM IAA/kinetin, yielding 4.8
and 4.7 shoots per explant, respectively, in 60 d. Rooting of regenerated shoots was achieved by leaving the explants in their
shoot-induction medium or transferring them to half-strength MS medium. Hardening of regenerated plants was successfully achieved
by planting them in peat moss substrate after a desiccation treatment at room temperature for 3 d. 相似文献
7.
L. Y. Solís-Ramos T. González-Estrada S. Nahuath-Dzib L. C. Zapata-Rodriguez E. Castaño 《Plant Cell, Tissue and Organ Culture》2009,96(3):279-287
Capsicum chinense is a recalcitrant species for in vitro morphogenesis, and up to date there is no efficient system for genetic transformation
and regeneration of this species via somatic embryogenesis. Here, we carried out an in vitro transformation of C. chinense via Agrobacterium tumefaciens co-cultivation with a system that expresses the heterologous gene WUSCHEL from Arabidopsis thaliana. WUSCHEL has been shown to promote the transition from vegetative to embryogenic state when overexpressed. We tested if the expression
of WUSCHEL in C. chinense would promote an embryogenic response in this species. After 15 days of induction, the segments of transformed stems begun
to form globular structures, suggesting that heterologus WUSCHEL was active and involved in the process of morphogenesis. 相似文献
8.
Sheng-Hui Xue Xin-Juan Luo Zhen-Hua Wu Hui-Li Zhang Xin-Yu Wang 《Plant Cell, Tissue and Organ Culture》2008,92(3):251-260
To explore the possibility of an effectively long-term preservation of the germplasm of the HR lines of medicinal plant Astragalus membranaceus, Gentiana macrophylla Pall., and Eruca sativa Mill., both cold storage and cryopreservation approaches were attempted and compared. After 5-month cold storage on half
strength Murashige and Skoog (1962) (1/2 MS) agar medium (AM), up to 82.9, 75.7, and 100% of the A. membranaceus, G. macrophylla and E. sativa hairy roots (HRs) recovered growth, respectively. The survival rates of A. membranaceus and G. macrophylla HRs significantly decreased, whereas that of E. sativa HR was unchanged with the addition of increased levels of exogenous abscisic acid (ABA) during cold storage. Using the encapsulation–vitrification
(EV) method for cryopreservation, the G. macrophylla HRs died, whereas up to 6 and 73% of the A. membranaceus and E. sativa HRs survived, respectively. The HR lines evaluated with both methods showed no significant differences in morphology and
growth rate compared with controls that were not subjected to preservation methods. These results suggest that cold storage
is a more suitable alternative for the HR lines of the three studied plant species and that specificity of plant species have
profound effects on the effectiveness of preservation. 相似文献
9.
Gaye Öngen Gaye Güngör Bahar Kanberoglu 《World journal of microbiology & biotechnology》2007,23(4):519-524
Aspergillus section Nigri strains Aspergillus aculeatus Ege-K 258, A.
foeditus var. pallidus Ege-K156, A. niger Ege-K 4 and A. tubingensis Ege-K 265 were used to treat olive mill wastewater (OMW) in an investigation aimed at exploring their dephenolisation and
decolourisation ability and, consequently, the economic feasibility of using any or all of these strains in a pre-treatment
step in the processing of OMW. Of these strains A. tubingensis Ege-K 265 resulted in an 80% decolourisation of twofold-diluted OMW and a 30% decolourisation of undiluted OMW; in addition,
it was able to remove approximately 30% of all phenolic compounds in both twofold-diluted and undiluted OMW. We conclude that
A. tubingensis Ege-K 265 could be effectively used in the pre-treatment step of a combined aerobic-anaerobic process to solve the environmental
problems caused by OMW in Mediterranean countries. 相似文献
10.
11.
Summary A new species of Eriocaulon, E. epedunculatum (Eriocaulaceae) is described and illustrated from the Western Ghats, India. 相似文献
12.
13.
Summary
Strobilanthes pothigaiensis, a new species of Strobilanthes (Acanthaceae) allied to S. foliosus T. Anderson from southern Western Ghats, India, is described and illustrated. 相似文献
14.
S. E. Dawson 《Kew Bulletin》2008,63(3):517-517
Summary The name Pavetta modesta (Hiern) S. E. Dawson is a later homonym of P. modesta Bremek. Pavetta crystalensis is proposed as a new name. 相似文献
15.
Khomaini Hasan Wangsa Tirta Ismaya Idar Kardi Yandi Andiyana Susanti Kusumawidjaya Safri Ishmayana Toto Subroto Soetijoso Soemitro 《Biologia》2008,63(6):1044-1050
α-Amylase from Saccharomycopsis fibuligera R-64 was successfully purified by butyl Toyopearl hydrophobic interaction chromatography, followed by Sephadex G-25 size
exclusion and DEAE Toyopearl anion exchange chromatography. The enzyme has a molecular mass of 54 kDa, as judged by SDS PAGE
analysis. Upon tryptic digestion, two major fragments with relative molecular masses of 39 kDa and 10 kDa, which resemble
the A/B and C-terminal domains in the homologous Taka-amylase, were obtained and were successfully separated with the Sephadex
G-50 size exclusion column. The 39-kDa fragment demonstrated a similar amylolytic activity to that of the undigested enzyme.
However, it was found that the K
m value of the 39-kDa fragment was about two-times higher than that of the undigested enzyme. Moreover, thermostability studies
showed a lower half-life time for the 39-kDa fragment. These findings suggest that the 39-kDa fragment is the catalytic domain,
while the 10-kDa fragment is the C-terminal one, which plays a role in thermostability and starch binding. Although the undigested
enzyme is able to act on raw starches at room temperature, with maize starches as the best substrate, neither the undigested
enzyme nor the fragments adsorb the tested raw starches. These results propose Saccharomycopsis fibuligera α-amylase as a raw starch-digesting but not adsorbing amylase, with a similar domain organization to that of Taka-amylase A. 相似文献
16.
Dae-Sung Lee Min-Seung Kang Hye-Jin Hwang Sung-Hwan Eom Ji-Young Yang Myung-Suk Lee Won-Jae Lee You-Jin Jeon Jae-Sue Choi Young-Mog Kim 《Biotechnology and Bioprocess Engineering》2008,13(6):758-764
We have been attempting for some time to discover a compound evidencing antibacterial activity against methicillin-resistant
Staphylococcus aureus (MRSA). The dieckol isolated from Ecklonia stolonifera has been shown to exhibit antibacterial activity against methicillin-susceptible S. aureus (MSSA) and MRSA. The minimum inhibitory concentrations (MICs) of dieckol were determined in a range of 32 to 64 μg/mL against
standard MSSA and MRSA strains. Furthermore, dieckol clearly reversed the high-level ampicillin and penicillin resistance
of MRSA. The MICs of ampicillin against two standard strains of MRSA were dramatically reduced from 512 to 0.5 μg/mL in combination
with 1/4 MIC of dieckol (16 μg/mL). The fractional inhibitory concentration (FIC) indices of ampicillin and penicillin were
measured from 0.066 to 0.266 in combination with 8 or 16 μg/mL of dieckol against all tested MRSA strains, thereby suggesting
that dieckol-ampicillin or dieckol-penicillin combinations exert a synergistic effect against MRSA. The results of this study
indicate that dieckol, administered in combination with β-lactams, may prove effective in the treatment of MRSA infections.
Our finding may also contribute to the development of an alternative phytotherapeutic anti-MRSA agent. 相似文献
17.
Mario C. N. Saparrat Geraldine E. Fermoselle Sebastián A. Stenglein Mónica B. Aulicino Pedro A. Balatti 《Mycopathologia》2009,168(1):41-47
Pseudocercospora griseola is the causal agent of angular leaf spot of common bean (ALS). It has undergone parallel coevolution with its host and two
major groups have been defined, “Andean” (P. griseola f. griseola) and “Mesoamerican” (P. griseola f. mesoamericana). The aim of this study was to analyze the nature and the level of the dark pigment synthesized by the representatives of
each group. After 21 days of incubation on potato dextrose agar medium, P. griseola f. griseola isolate S3b developed colonies with diameters of 17.5 ± 1.3 mm and concentric rings of pigmentation. Isolate T4 of P. griseola f. mesoamericana presented smaller colonies (9.9 ± 0.3 mm) with a uniform dark-gray color. Both isolates, S3b and T4, produced the same pigment,
a 1,8-dihydroxynaphthalene-melanin, although different in quantity and structural features as suggested by the IR spectrum.
The P. griseola f. griseola isolate S3b had a higher growth rate and melanin content as well as smaller sensitivity to melanin synthesis inhibitors compared
to the isolate T4 of P. griseola f. mesoamericana. These results suggest a possible link between melanin and growth in P. griseola. 相似文献
18.
S. Kumar Sunil Kumar S. P. Negi J. K. Kanwar 《In vitro cellular & developmental biology. Plant》2008,44(6):474-479
Callus cultures derived from leaf segments of chrysanthemum cultivar ‘Snow Ball’ which was susceptible to Septoria obesa were successfully used for in vitro selection for resistance to this pathogenic fungus. Resistant cell lines were selected by culturing callus on growth medium
containing various concentrations of S. obesa filtrate. Resistant calluses obtained after two cycles (30 d each cycle) of selection were used for plant regeneration. About
30% of the plants regenerated from the resistant calluses and 70–80% of the plants raised from cuttings had acquired considerable
resistance against the pathogen in the field. No phenotypic variation was observed in the selected regenerates. 相似文献
19.
Tarun Kumar Verinder Wahla Piyush Pandey R. C. Dubey D. K. Maheshwari 《World journal of microbiology & biotechnology》2009,25(2):277-285
Biological control of the cyst forming nematode Heterodera cajani was studied on sesame using plant growth promoting rhizobacteria (PGPR) Pseudomonas aeruginosa LPT3 and LPT5. Based on plant growth promoting attributes, two fluorescent pseudomonads, LPT3 and LPT5 were evaluated for
their efficacy against cyst forming nematode Heterodera cajani that parasitize Sesamum indicum. Pseudomonas aeruginosa LPT5 produced IAA, HCN, chitinase, glucanase and siderophore, and also solubilized inorganic phosphate in vitro. Moreover,
LPT5 resulted in mortality of second stage juveniles of H. cajani, which was 13% higher as compared to P. aeruginosa LPT3. Interestingly, when both strains were inoculated together for the management of H. cajani on Sesamum indicum the population of H. cajani was reduced significantly, in field trial. Approximately 60% reduction in cyst and juveniles population was recorded with
LPT5 coated seeds, while LPT3 resulted in 49% reduction in cyst and juvenile population as compared to control. Plants grown
with seeds bacterized with LPT5 and reduced doses of urea, diammonium phosphate (DAP), muriate of potash (K) and gypsum gave
maximum increase in yield, in comparison to that of plants raised under the influence of recommended or full doses of the
chemical fertilizers. Pseudomonas aeruginosa LPT5 also showed excellent root colonization. 相似文献
20.
The architecture of the musculature of the eutardigrade species Milnesium tardigradum Doyère, 1840, Hypsibius sp. and Ramazzottius oberhaeuseri (Doyère in Ann Sci Nat Zool Sér 2(14):269–369, 1840) is investigated by phalloidin staining and confocal laser scanning microscopy. There are methodological problems in staining
eutardigrades due to physiological alterations under stress (anhydrobiosis) and due to penetration problems of the cuticle.
It is helpful to fix specimens in the state of asphyxy, where animals are stretched following an oxygen shortage in their
environment. The musculatures of all three species correspond in their general architecture, but differ in detail, such as
in the number of muscles. All muscles are isolated muscle strands. There are on each body side two dorsal and one ventral
muscle strands, in addition to a system of dorsoventral, lateral and lateroventral muscles. Seven median ventral attachment
points give rise to dorsoventral, ventrolateral and appendage muscles. The appendages receive several muscles originating
dorsally and ventrally. The number of muscles and the arrangement differ in each appendage. The fourth appendage shows the
greatest differences with a far smaller number of muscles compared to other species. The musculature shows comparably few
strict segmental patterns, for example, the musculature of each appendage differs from the other ones. By comparison with
literature data on the same species and data of Macrobiotus hufelandi it can be shown that eutardigrades have a roughly comparable muscular architecture, but that there are several differences
in detail.
Dedicated to Professor Westheide on the occasion of his 70th birthday. 相似文献