共查询到20条相似文献,搜索用时 15 毫秒
1.
K. Samuel D. Debashish B. Madhumita G. Padmaja Siva Ram Prasad V. Bhaskara Ramana Murthy P. S. Rao 《In vitro cellular & developmental biology. Plant》2009,45(4):466-473
The propagation of Givotia rottleriformis Griff. is difficult as a result of long seed dormancy associated with poor seed germination. The present study was undertaken
to develop a protocol to overcome seed dormancy by culture of zygotic embryo axes and then develop an efficient method for
micropropagation of Givotia. Best germination frequency (78.3%) was achieved from mature zygotic embryo axes isolated from acid-scarified fresh seeds
when cultured on Murashige and Skoog (MS) medium (half-strength major salts) with 28.9 μM gibberellic acid (GA3). Efficient plant conversion was achieved by transfer of 10-d-old germinated embryos to MS medium (half-strength major salts)
supplemented with 1.2 μM kinetin (KN) and 0.5 μM indole-3-butyric acid (IBA). However, acid scarification of 1-yr-old seeds
decreased the germination frequency of zygotic embryo axes in comparison to those obtained from non-acid-scarified seeds which
germinated (96.2%) and converted into plants (80.3%) on MS basal (half-strength major salts) medium. Multiple shoot bud induction
was achieved by culture of shoot tips derived from in vitro germinated seedlings on MS medium with 0.5 μM thidiazuron for 4 wk, and the shoots elongated after transfer to a secondary
medium with 1.2 μM KN. A maximum number of 7.8 shoots per explant with an average shoot length of 3.2 cm was achieved after
two subcultures on this medium. The in vitro regenerated shoots rooted (41.5%) on half-strength MS medium with 0.5 μM IBA. The in vitro generated seedlings and micropropagated plants were established in soil with a survival frequency of 70% and 60%, respectively. 相似文献
2.
Seeds of Delphinium fissum subsp. sordidum are physiologically dormant at maturity, with underdeveloped embryos; thus they have morphophysiological dormancy (MPD).
The aims of this study were to determine the requirements for embryo growth, dormancy break and germination, to characterise
the type of seed dormancy and to evaluate the effects of light, seed age, pollination mechanism, and inter-annual and inter-population
variability on germinative ability. After 3 months of incubation at 5°C (cold stratification) in darkness conditions, the
mean embryo length increased from 5.6 to 2.07 mm, with 76% of seeds germinating. Conversely, embryos of seeds incubated during
3 months at 20/7 or 28/14°C hardly grew and no germination was recorded. Since cold stratification was the only requirement
for the loss of MPD, and both dry storage in laboratory conditions and warm stratification prior to cold stratification shortened
the cold stratification period required for germination, it could be concluded that D. fissum subsp. sordidum seeds have intermediate complex MPD. Cold stratification and incubation in darkness conditions promoted higher germination
percentages than those in light. In addition, germinative ability increased with seed age up to 8 months (reaching 96% at
5°C in darkness), showed a pronounced inter-annual and inter-population variability, as well as a significant decrease in
seeds coming from pollination by geitonogamy. High temperatures (25/10 or 28/14°C) induced seeds to secondary dormancy, so
seedling emergence in the greenhouse was restricted to February–March. The requirements for dormancy break and germination
reflect an adaptation to trigger germination in late winter. This study is the first one to document a gradual increase in
germination percentage with seed age for plant species with intermediate complex MPD. 相似文献
3.
C. Chang J. M. Feng H. Q. Si B. Yin H. P. Zhang C. X. Ma 《Molecular breeding : new strategies in plant improvement》2010,25(3):517-525
Pre-harvest sprouting (PHS) can easily lead to yield losses of wheat and downgrading of grain quality in wheat-growing areas
where long periods of wet weather occur frequently during harvest. As a main component of PHS, seed dormancy is often evaluated
by germination index (GI). Previous researches have proved allelic variations of Vp-1B to have a close relationship with dormancy of white-grained wheat. In the present study, a mapping population covering 157
recombinant inbred lines was developed from a cross of two white-grained varieties, Wanxianbaimaizi and Jing411. Wanxianbaimaizi
is a strongly dormant landrace carrying a novel allele, Vp-1Bf; whereas, Jing411 is a non-dormant variety with wild allele, Vp-1Ba. Our objective was to validate the association between the novel allele and seed dormancy using the population. The results
of sequences alignment indicated an insertion of 193 bp and a deletion of 109 bp were both identified in the novel allele,
respectively, compared with wild allele in Jing411. Here, the deletion was first detected. As for lines possessing Vp-1Ba, the average GI value was 0.584, significantly higher than that of lines holding Vp-1Bf. Among three genotypes, Vp-1Bf allele was generally corresponded to the lowest average of GI value (0.195), and the highest dormancy; in addition, lines
with heterozygous genotype often showed intermediate GI value (0.356). Of 92 RILs with Vp-1Ba, over 70 lines showed higher GI value (>0.40), and only about 7 lines had lower GI value (<0.20). On the other hand, among
60 RILs with Vp-1Bf, over 50 lines showed lower GI value (<0.40), and only about 7 lines had higher GI value (>0.60). The result of composite
interval mapping revealed that a major QTL for seed dormancy was flanked by Xwmc446 and Vp1 on 3BL, which was proximal to Vp1 (7.6–8.4 cM). The locus could explain 24.6–40.7% of total phenotypic variation across three crop seasons. The above results
could confirm that the novel allele had a striking association with high seed dormancy, and may be useful for improving PHS
tolerance of white-grained wheat. 相似文献
4.
Two plant growth promoting rhizobacteria––Sinorhizobium meliloti RMP1 and Pseudomonas aeruginosa GRC2 were studied for integrated nutrient management to obtain improved yield of Brassica juncea. Low concentrations of urea and diammonium phosphate (DAP) stimulated the growth of both S. meliloti RMP1 and P. aeruginosa GRC2. 1 M of urea and 0.35 M of DAP was found lethal for RMP1, while 1.3 M and 0.37 M concentrations of urea and DAP proved to
be toxic for GRC2. Lc50 was observed as 0.49 M of urea and 0.15 M of DAP for RMP1, and 0.66 M urea and 0.18 M of DAP for GRC2. Urea and DAP adaptive variants of RMP1 and GRC2 was isolated. Adaptive bacterial variants had better growth rates at sub-lethal (Lc50) concentrations of urea and DAP as compared to non-adaptive variants. They also retained plant growth promoting attributes
similar to non adaptive variants. GRC2 and RMP1 did not affect the growth of each other and were chemotactically active for DAP, urea as well as root exudates of
B. juncea. Both the isolates colonized well in the rhizosphere of B. juncea, as their populations were recorded ≈5 log10 cfu g−1 after 120 days. Interestingly, the colonization ability was found even better when both strains were co-inoculated, as their
population was recorded in the range of ≈6 log10 cfu g−1 after 120 days. In field trials, application of RMP1 and GRC2 resulted in significant increase in biomass and yield of B. juncea as compared to control. However, yield was better with application of half dose and full dose of recommended fertilizers.
Interestingly, the biomass as well as yield improved further when both isolates were applied together along with half dose
of recommended fertilizers. 相似文献
5.
A genetic transformation system has been developed for callus cells of Crataegus
aronia using Agrobacterium
tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with
5 mg l−1 Indole-3-butyric acid (IBA) and 0.5 mg l−1 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different
types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red
colored callus was obtained on MS medium supplemented with 2 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l−1 kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli
were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l−1 hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this
is the first time to report an Agrobacterium-mediated transformation system in Crataegus
aronia. 相似文献
6.
Elizabeth Fullam Akane Kawamura Helen Wilkinson Areej Abuhammad Isaac Westwood Edith Sim 《The protein journal》2009,28(6):281-293
Arylamine N-acetyltansferase (NAT) from Mycobacterium tuberculosis (TBNAT) is a potential drug target for anti-tubercular therapy. Recombinant TBNAT is much less soluble and is produced in
lower yields than the closely related NAT from Mycobacterium marinum (MMNAT). In order to explore MMNAT as a model for TBNAT in drug discovery, we compare the two mycobacterial NAT enzymes.
Two site-directed mutants of MMNAT have been prepared and characterised: MMNAT71, Tyr → Phe and MMNAT209, Met → Thr, in which
residues within 6 Å of the active-site cysteine have been replaced with the corresponding residue from TBNAT. Two chimeric
proteins have also been produced in which the third domain of MMNAT has been replaced by the third domain of TBNAT and vice
versa. The activity profile of the chimeric proteins suggests a role for the third domain in the evolutionary divergence of
NAT between these closely related mycobacterial species. 相似文献
7.
Toshinari Godo Miho Komori Emi Nakaoki Tomohisa Yukawa Kazumitsu Miyoshi 《In vitro cellular & developmental biology. Plant》2010,46(3):323-328
The effects of culture conditions on the asymbiotic germination of mature seeds of Calanthe tricarinata Lindl., an endangered terrestrial cool-climate orchid, were examined. Specifically, conditions such as illumination, temperature,
and the addition of plant growth regulators to the medium were studied. Mature seeds were harvested from plants that had been
collected in Toyama Prefecture, Japan, and maintained at the Botanic Gardens of Toyama. Solidified “New Dogashima” medium
was used as the basal medium, and it was supplemented with 6-benzyladenopurine (BA) or α-naphthalene acetic acid (NAA). White
light at 40 μmol m−2 s−1, with a 16-h photoperiod, inhibited the germination of seeds by 53–80%, as compared to dark controls in genotypes examined.
The optimal temperature for the germination of seeds in darkness was 20°C and the germination frequency reached 60%, whereas
it was only 28% at 25°C. While both NAA and BA stimulated germination, BA was more effective than NAA. After storage for 18 mo
at 5°C, seeds incubated on medium that contained 0.2 mg l−1 BA germinated at a frequency of 36%, which was twice that of seeds grown without any plant growth regulators. The frequency
of subsequent germination decreased during storage of seeds at 5°C for approximately 2 yr, dropping from 61% to 13%. The protocorms
obtained in this study were developed to plantlets readily after transferring to fresh 1/2 MS medium without any plant growth
regulators. They were successfully acclimatized in green house after two to three subcultures in vitro. The significant role of a reproducible protocol for the germination of mature seeds is discussed in terms of the ex situ conservation of endangered orchid species. 相似文献
8.
9.
Philip J. Kauth Michael E. Kane Wagner A. Vendrame 《In vitro cellular & developmental biology. Plant》2011,47(1):148-156
Seed responses to temperature are often essential to the study of germination ecology, but the ecological role of temperature
in orchid seed germination remains uncertain. The response of orchid seeds to cold stratification have been studied, but the
exact physiological role remains unclear. No studies exist that compare the effects of either cold stratification or temperature
on germination among distant populations of the same species. In two separate experiments, the role of temperature (25, 22/11,
27/15, 29/19, 33/24°C) and chilling at 10°C on in vitro seed germination were investigated using distant populations of Calopogon tuberosus var. tuberosus. Cooler temperatures promoted germination of Michigan seeds; warmer temperatures promoted germination of South Carolina and
north central Florida seeds. South Florida seed germination was highest under both warm and cool temperatures. More advanced
seedling development generally occurred at higher temperatures with the exception of south Florida seedlings, in which the
warmest temperature suppressed development. Fluctuating diurnal temperatures were more beneficial for germination compared
to constant temperatures. Cold stratification had a positive effect on germination among all populations, but South Carolina
seeds required the longest chilling treatments to obtain maximum germination. Results from the cold stratification experiment
indicate that a physiological dormancy is present, but the degree of dormancy varies across the species range. The variable
responses among populations may indicate ecotypic differentiation. 相似文献
10.
We examined the response of seeds to heat in four geographically restricted and one widespread species of shrubby Darwinia from the fire-prone region of southeastern Australia. These shrubs are killed by fire and rely on seed germination after
a fire to maintain populations. We replicated the germination trials across several sites and several fruiting seasons for
most species. Seeds had a high level of viability and were largely dispersed in a dormant state, except in D. glaucophylla, where seed dormancy varied significantly across fruiting seasons. The indehiscent fruit of all species readily imbibes moisture
when wet and seeds are not considered to be ‘hard-seeded’. All species had increased seed germination in response to a limited
range of heating temperatures (generally 80–100°C). Higher temperatures killed increasing proportions of seeds. This pattern
was broadly consistent across species, population and seasons, although the proportion of seeds whose germination was promoted
by heat varied from high (D. diminuta, D. fascicularis, D. glaucophylla) to moderate (D. biflora, D. procera). Our work highlights the importance of heat as a mechanism for influencing germination in species that are not hard-seeded.
Consequently, soil temperatures during a fire should strongly influence post-fire germination levels in Darwinia. The roles of other cues that promote germination, i.e. smoke, seasonal temperatures and their interactions with heat, remain
to be investigated. 相似文献
11.
Konstantin V. Kiselev Anna V. Turlenko Yuri N. Zhuravlev 《Plant Cell, Tissue and Organ Culture》2009,99(2):141-149
A somatic embryogenesis protocol for plant regeneration of northern red oak (Quercus rubra) was established from immature cotyledon explants. Embryogenic callus cultures were induced on Murashige and Skoog medium
(MS) containing 3% sucrose, 0.24% Phytagel™, and various concentrations of 2,4-dichlorophenoxyacetic acid (2,4-d) after 4 weeks of culture in darkness. A higher response (66%) of embryogenic callus was induced on 0.45 μM 2,4-d. Higher numbers of globular- (31), heart- (17), torpedo- (12), and cotyledon-stage (8) embryos per explant were obtained
by culturing embryogenic callus on MS with 3% sucrose, 0.24% Phytagel™, and devoid of growth regulators after 8 weeks culture
in darkness. Continuous sub-culturing of embryogenic callus on medium containing 2,4-d yielded only compact callus. Desiccation of embryos for 3 days in darkness at 25 ± 2°C followed by cold storage at 4°C in
darkness for 8 weeks favored embryo germination and development of plantlets. Cotyledon-stage embryos subjected to desiccation
and chilling treatment cultured on MS with 3% sucrose, 0.24 Phytagel™, 0.44 μM 6-benzylaminopurine (BA), and 0.29 μM gibberellic
acid germinated at a higher frequency (61%) than with 0.44 μM BA alone and control cultures. Germinated plantlets developed
a shoot and root, were acclimatized successfully, and maintained in a growth room for plantlet development. 相似文献
12.
Marcin Zarek 《In vitro cellular & developmental biology. Plant》2007,43(6):623-630
Conditions for obtaining an efficient mass propagation procedure to overcome isolated Taxus baccata embryo dormancy were investigated. The protocol herein described was efficient for overcoming the dormancy of T. baccata isolated embryos under in vitro conditions, enabling the conservation and propagation of this species. T. baccata seeds were unable to germinate directly after collection under in vitro conditions. Very good sterility and germination was achieved by soaking seeds in distilled water at a low temperature (+4°C)
at least for 48 h instead of leaching them for 7 d under running water, followed by maintaining isolated embryos on the Murashige
and Skoog medium (MS) supplemented with 5 g l−1 activated charcoal. That treatment allowed one to shorten the time of the experiment and gave almost 100% sterility. The
best germination was observed in darkness, but to obtain worthy seedlings, it was necessary to place cultures in a 16-h photoperiod
after a 2-wk incubation. There was no significant difference in germination between seeds collected from different populations
of Southern Poland. 相似文献
13.
Juan A. Delgado José M. Serrano Francisco López Francisco J. Acosta 《Plant Ecology》2008,197(2):269-276
The germination response of different sized seeds from individuals of a Mediterranean fire-prone shrub (Cistus ladanifer) was investigated in relation to pre-germination heating. A control (no heating), a low temperature during a short exposure
time (50°C during 5 min), a high temperature during a short exposure time (100°C during 5 min) and a high temperature during
a long exposure time (100°C during 15 min) were applied to seeds from different individual plants with different mean seed
weight. These pre-germination treatments resemble natural germination scenarios for the studied species, absence of fire,
low intensity pasture fire, typical Mediterranean shrub fire, and severe fire with high fuel load. Mean seed weight only showed
a marginally significant positive correlation with the proportion of germinated seeds whatever the pre-germination treatment.
These results suggest that seed dormancy is unrelated to seed size and that under the experimental conditions used in this
study, the effect of seed size on seed germination is low. Nevertheless, larger seeds could be favoured in natural conditions,
especially under the high competition scenario which arise after wildfires. Control seeds showed a negative correlation between
seed size and germination velocity suggesting that lighter seeds could take advantage from early germination in recruitment
events in the absence of wildfires. Nevertheless, even the lower pre-germination heating treatment turns this correlation
in not significant, suggesting a strong selection pressure (unrelated to seed size) for early germination after fire events.
In our study, different sized seeds of C. ladanifer seem to perform better under different germination scenarios suggesting that seed size variation could be maintained by the
alternation of recruitments without wildfires and recruitments after wildfire events. 相似文献
14.
Wen Liu Xuesen Chen Guanjun Liu Qing Liang Tianming He Jianrong Feng 《Plant Cell, Tissue and Organ Culture》2007,88(3):289-299
Embryo rescue technique was used successfully to produce interspecific hybrids by crossing peach (P. persica) as a female parent with apricot (P. armeniaca) and plum (P. salicica). In those crosses that had ‘Yuhualu’ or ‘Zhonghuashoutao’ as female parents, hybrid embryos aborted from the 7th or 8th
week after pollination mainly due to post-pollination incompatibility. An embryo rescue protocol was established to rescue
such embryos and recover hybrid plants. Modified half-strength MS medium containing 4 mg l−1 6-BA and 0.5 mg l−1 IBA produced up to 90% germination in the embryos. Modified MS medium with 1.0 mg l−1 6-BA and 1.0 mg l−1 IBA gave the highest bud induction and multiplication whereas modified MS medium containing 0.5 mg l−1 IAA and 0.2 mg l−1 NAA gave the best rooting percentage. All the hybrids obtained using this embryo rescue technique were verified using simple
sequence repeat (SSR) markers. A series of pollen treatments were carried out to partially overcome pre-pollination incompatibility,
and it was found accidentally that pollen treatment with electrostatic field not only improved pollen germination but also
increased the multiplication coefficient of embryo-induced shoots. 相似文献
15.
Bemisia tabaci Genn. (Hemiptera: Aleyrodidae) and Frankliniella occidentalis (Thysanoptera: Thripidae) are major pests in greenhouse grown cucumber crops. Recently, Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) was shown an effective biological control agent of both pests. Hence, perhaps both pests
can be controlled simultaneously by this predator. However, with simultaneous infestation of both pests, synergistic effects,
or interference could affect biological control and perhaps require changes in release rates of the predator. Thus, the aim
of the present study was to evaluate different release rates of A. swirskii to control both pests under a worst case scenario of rapid immigration into a cucumber greenhouse. Two experiments were conducted,
one simulating the influx of whiteflies alone (whitefly experiment) and the other immigration of whiteflies and thrips together
(whitefly plus thrips experiment). Three treatments were compared in the whitefly experiment: (1) B. tabaci alone, (2) B. tabaci + 25 A. swirskii m−2 and (3) B. tabaci + 75 A. swirskii m−2. The high release rate was more effective than the low rate in controlling B. tabaci alone. The high rate was subsequently tested against B. tabaci and F. occidentalis for the whitefly and thrips experiment in which five treatments were compared: (1) B. tabaci alone, (2) F. occidentalis alone, (3) B. tabaci + 75 A. swirskii m−2, (4) F. occidentalis + 75 A. swirskii m−2 and (5) B. tabaci + F. occidentalis + 75 A. swirskii m−2. This rate of A. swirskii controlled whiteflies and thrips either alone or together. Therefore, 75 A. swirskii m−2 should be an adequate rate for controlling both pests either alone or simultaneously in cucumber greenhouses. 相似文献
16.
Locally isolated strains of a thermoalkalotolerant Streptomyces sp. and Aspergillus
fumigatus were used for the in vitro biosynthesis of silver nanoparticles from AgNO3 solutions. An autolysed cell-free culture filtrate from each strain was used, indicating that the formation mechanism depends
on intra-cellular components for both organisms, since culture broths had no significant nanoparticle formation potential.
Nanoparticle formation was indicated by a change of the solution from colourless or light brown to dark brown after 24 h or
more, and UV–visible spectroscopy and x-ray diffraction analysis confirmed the formation by both organisms. The initial formation
kinetics were faster with Aspergillus, but formation continued for a longer period with Streptomyces, resulting in higher concentrations after 48 h. Transmission electron microscope images revealed well dispersed nanoparticles
with diameters ranging from 15 to 45 nm from A. fumigatus, while those from Streptomyces sp. had a narrower size distribution of 15–25 nm. The higher productivity and preferred narrower size distribution of Streptomyces, together with its well established industrial use, may make it the preferred choice for further optimization studies. 相似文献
17.
Recent studies have identified common variants in or near GC, CYP2R1 and NADSYN1/DHCR7 to be associated with 25-hydroxyvitamin D [25(OH)D] levels in European populations. We aimed to examine whether these variants
also influence 25(OH)D levels in Chinese. Seven common variants were successfully genotyped and tested for associations with
plasma 25(OH)D levels in a population-based cohort of 3,210 Chinese Hans from Beijing and Shanghai. Six common variants at
GC (rs4588, rs7041, rs2282679 and rs1155563) and NADSYN1/DHCR7 (rs3829251 and rs1790349) loci were all significantly associated with lower plasma 25(OH)D levels (−0.036 ≤ β ≤ −0.076 per risk-allele, P ≤ 5.7 × 10−5), while CYP2R1-rs2060793 showed a trend toward association with 25(OH)D levels in the Shanghai subpopulation (P = 0.08), but not in the Beijing subpopulation (P = 0.82). Haplotype-based association analyses of the four GC variants showed that only the haplotype that contained all risk-alleles (TACC) was significantly associated with lower plasma
25(OH)D levels (β = −0.085, P = 2.3 × 10−9), while the haplotype containing the risk-alleles of rs4588 and rs2282679 (TATC) was marginally associated with lower 25(OH)D
levels (β = −0.054, P = 0.0562) when compared with GCTA haplotype carrying the four protective alleles. Most notably, conditional analyses showed
that only GC-rs4588 and GC-rs2282679 (r
2 = 0.97) remained significantly associated with 25(OH)D concentrations (P ≤ 1.9 × 10−5) after adjusting for the other two SNPs in GC. In conclusion, GC and NADSYN1/DHCR7 loci individually and collectively contribute to variation in plasma vitamin D levels in Chinese Hans. 相似文献
18.
Jerzy K. Kulski Atsuko Shigenari Takashi Shiina Kazuyoshi Hosomichi Makoto Yawata Hidetoshi Inoko 《Immunogenetics》2009,61(4):257-270
The study of the association of the Human Leukocyte Antigen (HLA) alleles and polymorphic retrotransposons such as Alu, HERV, and LTR at various loci within the Major Histocompatibility Complex allows for a better identification and stratification of disease associations and the origins of HLA haplotypes in different populations. This paper provides sequence and association data on two structurally polymorphic MER9-LTR retrotransposons that are located 54 kb apart and in close proximity to the multiallelic HLA-A gene involved in the regulation of the human immune system. Direct DNA sequencing and analysis of the PCR products identified DNA nucleotide variations between the MER9-LTR sequences at the two loci and their associations with HLA-A alleles as potential haplotype and evolutionary markers. All MER9-LTR sequences were haplotypic when associated with common HLA-A alleles. The number of SNP loci was 2.5 times greater for the solo LTR at the AK locus, which is located closer to the HLA-A gene than the solo or 3′ LTR at the HG locus. Our study shows that the nucleotide variations of the MER9-LTR DNA sequences are additional informative markers in fine mapping HLA-A genomic haplotypes for future population, evolutionary, and disease studies. 相似文献
19.
Serena Santolamazza-Carbone Montserrat Pestaña Nieto Rosa Pérez Otero Pedro Mansilla Vázquez Adolfo Cordero Rivera 《BioControl》2009,54(2):195-209
We investigated the effects of temperature, photoperiod, food and host availability, and body size on the overwintering abilities
of the egg parasitoid Anaphes nitens Girault (Hymenoptera, Mymaridae) under natural conditions. Seven groups of eighty females received one of four treatments
(n = 20): (i) honey and hosts, (ii) water and hosts, (iii) honey, or (iv) water. Seven groups of forty males received only honey
or water (n = 20). To test if short day-length is the main cue for larval dormancy, the experiment was replicated inside a climate chamber
at 20°C and under a winter photoperiod. A. nitens overwinters because of quiescence or oligopause inside the hosts and increased adult longevity. Mean pre-emergence mortality
was up to 26% indoors and 15.2% outdoors, males being more affected. Development time had a significant and positive effect
on body size. Honey-fed females without hosts had the highest longevity (53 days). Mother’s diet and size affected development
time, body size, longevity, and fecundity of the progeny. The results confirm the good adaptation of the parasitoid to the
environmental conditions of NW Spain and its ability to synchronize its life cycle with the phenology of the host.
Handling editor: Drik Babendreier. 相似文献
20.
Earlier, a pollen-specific Oryza sativa indica pollen allergen gene (OSIPA), coding for expansins/pollen allergens, was isolated from rice, and its promoter—upon expression in tobacco and Arabidopsis—was found active during the late stages of pollen development. In this investigation, to analyze the effects of different
putative regulatory motifs of OSIPA promoter, a series of 5′ deletions were fused to β-glucuronidase gene (GUS) which were stably introduced into rice and Arabidopsis. Histochemical GUS analysis of the transgenic plants revealed that a 1631 bp promoter fragment mediates maximum GUS expression
at different stages of anther/pollen development. Promoter deletions to −1272, −966, −617, and −199 bp did not change the
expression profile of the pollen specificity. However, the activity of promoter was reduced as the length of promoter decreased.
The region between −1567 and −199 bp was found adequate to confer pollen-specific expression in both rice and Arabidopsis systems. An approximate 4-fold increase in the GUS activity was observed in the pollen of rice when compared to that of Arabidopsis. As such, the OSIPA promoter seems promising for generation of stable male-sterile lines required for the production of hybrids in rice and other
crop plants. 相似文献