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1.
The aim of the research was to make a preliminary determination of the effectiveness of the induction of haploids in Capsicum frutescens L. In order to induce androgenesis red and yellow fruit forms of species were used, each bred by the researchers on their
own. The experiment was performed in October. Anther cultures were conducted according to a modified method developed by Dumas
et al. (1981) for C. annuum L. The anthers were laid on CP medium containing 0.01 mg dm−3 2.4-D and 0.01 mg dm−3 kinetin, with the addition of 0.5 g dm−3 of activated carbon and 5 mg×dm−3 of silver nitrate, solidified with 8 g dm−3 of agar. The cultures were incubated in the dark at 35 deg C for 8 days. Next they were transferred to 25 deg C under a 12-hour
photoperiod. After 14 days of induction, anthers were transferred to R1 medium supplemented with 0.1 mg dm−3 kinetin. Obtained embryos were subsequently transplanted onto V3 hormone-free medium and well growing plants were planted in greenhouses. The efficiency of androgenesis for both C. frutescens L. forms was relatively low and it did not exceed 5%. The ploidy level of the resulting plants was determined by flow-cytometric
analysis. The regenerants consisted of about equal numbers of haploids and diploids. Additionally, among plants regenerated
from anthers of yellow fruit forms, two mixoploids were observed. 相似文献
2.
Nitraria retusa and Atriplex halimus (xero-halophytes) plants were grown in the range 0–800 mM NaCl while Medicago arborea (glycophyte) in 0–300 mM NaCl. Salt stress caused a marked decrease in osmotic potential and a significant accumulation of
Na+ and Cl− in leaves of both species. Moderate salinity had a stimulating effect on growth rate, net CO2 assimilation, transpiration and stomatal conductance for the xero-halophytic species. At higher salinities, these physiological
parameters decreased significantly, and their percentages of reduction were higher in A. halimus than in N. retusa whereas, in M. arborea they decreased linearly with salinity. Nitraria retusa PSII photochemistry and carotenoid content were unaffected by salinity, but a reduction in chlorophyll content was observed
at 800 mM NaCl. Similar results were found in A. halimus, but with a decrease in the efficiency of PSII (F′v/F′m) occurred at 800 mM. Conversely, in M. arborea plants we observed a significant reduction in pigment concentrations and chlorophyll fluorescence parameters. The marked
toxic effect of Na+ and/or Cl− observed in M. arborea indicates that salt damage effect could be attributed to ions’ toxicity, and that the reduction in photosynthesis is most
probably due to damages in the photosynthetic apparatus rather than factors affecting stomatal closure. For the two halophyte
species, it appears that there is occurrence of co-limitation of photosynthesis by stomatal and non-stomatal factors. Our
results suggest that both N. retusa and A. halimus show high tolerance to both high salinity and photoinhibition while M. arborea was considered as a slightly salt tolerant species. 相似文献
3.
Luca Vitale Paul Di Tommasi Carmen Arena Angelo Fierro Amalia Virzo De Santo Vincenzo Magliulo 《Acta Physiologiae Plantarum》2007,29(4):317-326
Zea mays is cultivated in the Mediterranean regions where summer drought may lead to photoinhibition when irrigation is not available.
In this work the response of maize to water stress was evaluated by gas exchange measurements at the canopy and leaf level.
Leaf gas exchange was assessed before, during and after water stress, while canopy turbulent fluxes of mass and energy were
performed on a continuous basis. In the early growth period, a linear increment of net ecosystem photosynthetic rate (P
NE) to incoming of photosynthetic photon flux density (PPFD) was found and net leaf photosynthetic rate (P
NL) showed the tendency to saturate under high irradiance. During water stress, the relationship between P
NE and PPFD became curvilinear and both P
NE and P
NL saturated in a range between 1,000 and 1,500 μmol (photons) m−2 s−1. Leaf water potential (ψl) dropped from −1.50 to −1.88 MPa during water stress, indicating that leaf and canopy gas exchanges were limited by stomatal
conductance. With the restoration of irrigation, P
NE, P
NL and ψl showed a recovery, and P
NE and P
NL reached the highest values of whole study period. Leaf area index (LAI) reached a value of 3.0 m2 m−2. The relationship between P
NE and PPFD remained curvilinear and P
NE values were lower than those of a typical well-irrigated maize crop. The recovery in P
NE and P
NL after stress, and ψl values during stress indicate that the photosynthetic apparatus was not damaged while soil moisture stress after-effects
resulted in a sub-optimal LAI values, which in turn depressed P
NE. 相似文献
4.
Although resistance of microorganisms to Hg(II) salts has been widely investigated and resistant strains have been reported
from many eubacterial genera, there are few reports of mercuric ion resistance in extremophilic microorganisms. Moderately
thermophilic mercury resistant bacteria were selected by growth at 62 °C on Luria agar containing HgCl2. Sequence analysis of 16S rRNA genes of two isolates showed the closest matches to be with Bacillus pallidus and Ureibacillus thermosphaericus. Minimum inhibitory concentration (MIC) values for HgCl2 were 80 μg/ml and 30 μg/ml for these isolates, respectively, compared to 10 μg/ml for B. pallidus H12 DSM3670, a mercury-sensitive control. The best-characterised mercury-resistant Bacillus strain, B. cereus RC607, had an MIC of 60 μg/ml. The new isolates had negligible mercuric reductase activity but removed Hg from the medium
by the formation of a black precipitate, identified as HgS by X-ray powder diffraction analysis. No volatile H2S was detected in the headspace of cultures in the absence or presence of Hg2+, and it is suggested that a new mechanism of Hg tolerance, based on the production of non-volatile thiol species, may have
potential for decontamination of solutions containing Hg2+ without production of toxic volatile H2S. 相似文献
5.
An N-acetylglucosaminidase produced by Streptomyces cerradoensis was partially purified giving, by SDS-PAGE analysis, two main protein bands with Mr of 58.9 and 56.4 kDa. The Km and Vmax values for the enzyme using p-nitrophenyl-β-N-acetylglucosaminide as substrate were of 0.13 mM and 1.95 U mg−1 protein, respectively. The enzyme was optimally activity at pH 5.5 and at 50 °C when assayed over 10 min. Enzyme activity
was strongly inhibited by Cu2+ and Hg2+ at 10 mM, and was specific to substrates containing acetamide groups such as p-nitrophenyl-β-N-acetylglucosaminide and p-nitrophenyl-β-D-N,N′-diacetylchitobiose. 相似文献
6.
Chang-Ming Zhao Gen-Xuan Wang Xiao-Ping Wei Jian-Ming Deng Dong-Liang Cheng 《Trees - Structure and Function》2007,21(1):55-63
Physiological and photosynthetic responses were investigated at three different depths of groundwater (DGW: 1.4, 2.4, and
3.4 m) in Elaeagnus angustifolia L., a locally adapted tree to the arid region in northwest China. Predawn leaf water potential and chlorophyll content declined
gradually with the increasing DGW, whereas there was little effect on predawn variable-to-maximum chlorophyll fluorescence
ratio F
v/F
m and leaf carotenoid compositions (xanthophyll cycle pool, neoxanthin, lutein, and β-carotene). Net photosynthetic rate (P
n), quantum yield of PSII electron transport (ΦPSII), stomatal conductance (Gs), and intercellular CO2 concentration (Ci) declined obviously; however, P
n decreased more than ΦPSII at deeper DGW. The photoinhibition of PSII at all three DGW occurred at midday in summer and increased as DGW increased.
The ΔpH-dependent thermal dissipation and the level of de-epoxidation of the xanthophyll cycle at all three DGW reached their
maxima at midday with the increase of light intensity. However, the fraction of functional PSII and light intensity at deeper
DGW (2.4, 3.4 m) showed a negative correlation. This correlation suggested that most of violaxanthin was converted into zeaxanthin
at midday, and the reversible inactivation of partial PSII reaction centers took place at deeper DGW. These results together
suggest that both the xanthophyll cycle-dependent thermal dissipation and the reversible inactivation of partial PSII might
have played important roles in avoiding the excess light-induced energy damage in leaves of this tree species at deeper DGW. 相似文献
7.
J. Rodríguez-Calcerrada J. A. Pardos L. Gil I. Aranda 《Trees - Structure and Function》2007,21(1):45-54
Photosynthetic acclimation of two co-occurring deciduous oaks (Quercus petraea and Quercus pyrenaica) to a natural light gradient was studied during one growing season. In the spring of 2003, 90 seedlings per species were
planted along a transect resulting from a dense Pinus sylvestris stand, an adjacent thinned area and a 10-m-wide firebreak (16.5–60.9% Global Site Factor (GSF)). In two dates of the following
summer, we measured leaf gas exchange, carboxylation efficiency (CE), chlorophyll and nitrogen content, light–response curves
of chlorophyll a fluorescence parameters, and leaf mass per area (LMA). Summer was mild, as evidenced by leaf predawn water potential (Ψpd), which reduced the interactive effect of water stress on the response of seedlings to light. Q. pyrenaica had higher LMA, CE, stomatal conductance (g
s max) and photosynthesis per unit area than Q. petraea at all growth irradiances. , LMA, g
s max and electron transport rate (ETR) all increased with light availability (GSF) in a similar fashion in both species. Light
had also a clear effect on the organization of Photosystem II (PS II), as deduced by chlorophyll a fluorescence curves. Chlorophyll concentration (Chlm) decreased with increasing light availability in Q. pyrenaica but it did not in Q. petraea. Seedlings of Q. petraea acclimated to higher irradiances showed a greater non-photochemical quenching (NPQ) than those of Q. pyrenaica. This suggests a higher susceptibility to high light in Q. petraea, which would be consistent with a better adaptation to shade, inferred from the lower LMA or the lower rate of photosynthesis. 相似文献
8.
Propagation by softwood canes and cuttings is preferred as a practical system for vegetative reproduction of many ornamental
plant species, despite the advances in tissue culture techniques. Dracaena purplecompacta L. is a species that has a high demand for exports. Conversely, coconut water (CW) is a rich supplement that naturally contains
plant growth regulators such as indole acetic acid (IAA). The objective of this work was to evaluate the potential of CW extracts
containing natural IAA, on adventitious root development in vegetative propagation of ornamental plant canes of D. purplecompacta L. Five different concentrations (28, 57, 143, 286, 571 μM of natural IAA) of CW extracts were tested. Another set of treatment
was carried out with the same concentrations of authentic IAA hormone for comparison purpose. The 143-μM IAA CW extract recorded
the best root induction and development. It was found that the root expression was faster (5 weeks) with the use of the novel
method. In the conventional method, the canes are propagated by quick dip application of commercial product containing artificial
hormone IAA and placing them on coir fiber dust beds. It takes up to 6 weeks for the canes to develop adventitious roots to
the desired level. Steeping canes in 143-μM IAA CW extract improved rooting in D. purplecompacta L., and it was comparable to the application of 143-μM authentic IAA. The study indicates that adventitious root development,
shoot development, and leaf emergence of D. purplecompacta L. is promoted by IAA CW extracts. 相似文献
9.
Zahir Ahmad Zahir Usman Ghani Muhammad Naveed Sajid Mahmood Nadeem Hafiz Naeem Asghar 《Archives of microbiology》2009,191(5):415-424
Ethylene synthesis is accelerated in response to various environmental stresses like salinity. Ten rhizobacterial strains
isolated from wheat rhizosphere taken from different salt affected areas were screened for growth promotion of wheat under
axenic conditions at 1, 5, 10 and 15 dS m−1. Three strains, i.e., Pseudomonas putida (N21), Pseudomonas aeruginosa (N39) and Serratia proteamaculans (M35) showing promising performance under axenic conditions were selected for a pot trial at 1.63 (original), 5, 10 and 15 dS m−1. Results showed that inoculation was effective even in the presence of higher salinity levels. P. putida was the most efficient strain compared to the other strains and significantly increased the plant height, root length, grain
yield, 100-grain weight and straw yield up to 52, 60, 76, 19 and 67%, respectively, over uninoculated control at 15 dS m−1. Similarly, chlorophyll content and K+/Na+ of leaves also increased by P. putida over control. It is highly likely that under salinity stress, 1-aminocyclopropane-1-carboxylic acid-deaminase activity of
these microbial strains might have caused reduction in the synthesis of stress (salt)-induced inhibitory levels of ethylene.
The results suggested that these strains could be employed for salinity tolerance in wheat; however, P. putida may have better prospects in stress alleviation/reduction. 相似文献
10.
The dwarf pomegranate (Punica granatum L. var. nana) is a dwarf ornamental plant that has the potential to be the model plant of perennial fruit trees because it bears fruits
within 1 year of seedling. We established an Agrobacterium-mediated transformation system for the dwarf pomegranate. Adventitious shoots regenerated from leaf segments were inoculated
with A. tumefaciens strain EHA105 harboring the binary vector pBin19-sgfp, which contains neomycin phosphotransferase (npt II) and green fluorescent protein (gfp) gene as a selectable and visual marker, respectively. After co-cultivation, the inoculated adventitious shoots were cut
into small pieces to induce regeneration, and then selected on MS medium supplemented with 0.5 μM α-naphthaleneacetic acid
(NAA), 5 μM N6-benzyladenine (BA), 0.3% gellan gum, 50 mg/l kanamycin, and 10 mg/l meropenem. Putative transformed shoots were regenerated
after 6–8 months of selection. PCR and PCR-Southern blot analysis revealed the integration of the transgene into the plant
genome. Transformants bloomed and bore fruits within 3 months of being potted, and the inheritance of the transgene was confirmed
in T1 generations. The advantage of the transformation of dwarf pomegranate was shown to be the high transformation rate. The establishment
of this transformation system is invaluable for investigating fruit-tree-specific phenomena. 相似文献
11.
The objectives of this research were first to isolate plastid gene sequences from cabbage (Brassica oleracea L. var. capitata L.), and to establish the chloroplast transformation technology of Brassica. A universal transformation vector (pASCC201) for Brassica chloroplast was constructed with trnV–rrn16S (left) and trnI–trnA–rrn23S (right) of the IRA region as a recombination site for the transformed gene. In transforming plasmid pASCC201, a chimeric aadA gene was cloned between the rrn16S and rrn23S plastid gene borders. Expression of aadA confers resistance to spectinomycin and streptomycin antibiotics. The uidA gene was also inserted into the pASCC201 and transferred into the leaf cells of cabbage via particle gun mediated transformation.
Regenerated plantlets were selected by 200 mg/l spectinomycin and streptomycin. After antibiotic selection, the regeneration
percentage of the two cabbage cultivars was about 2.7–3.3%. The results of PCR testing and Southern blot analysis confirmed
that the uidA and aadA genes were present in the chloroplast genome via homologously recombined. Northern blot hybridizations, immunoblotting and
GUS histochemical assays indicated that the uidA gene were stable integrated into the chloroplast genome. Foreign protein was accumulated at 3.2–5.2% of the total soluble
protein in transgenic mature leaves. These results suggest that the expression of a variety of foreign genes in the chloroplast
genome will be a powerful tool for use in future studies. 相似文献
12.
M. V. B. Figueiredo H. A. Burity C. R. Martínez C. P. Chanway 《World journal of microbiology & biotechnology》2007,23(2):187-193
A greenhouse experiment was carried out aiming to evaluate the response to drought stress of cowpea nodule enzymatic activities
during different plant developmental stages leading to biological N2 fixation. Stress was applied by controlling soil’s water-potential through a porous cup. Cowpea plants cv IPA 205 were grown
in pots with yellow latosol soil under three different matric potential (ψm) treatments. Even with high evaporative demand and limited soil water availability, cowpea could not induce an extremely
low leaf water potential (ψw). Sap ureides concentration in cowpea declined during the drought stress period. There was a decline in enzyme activity in
the metabolic pathways concerned with N2 fixation: NADH-dependent glutamate synthase (EC 1.4.1.14), glutamine synthetase (EC 6.3.1.2) and phosphoenolpyruvate carboxylase
(EC 4.1.1.31). In contrast, an increase in glutamate dehydrogenase (EC 1.4.1.4) was observed as the ψm declined. Metabolism associated with N2 assimilation was impaired every time that the ψw was reduced below −0.73 MPa as had happened in the stressed treatments. The stress applied by the porous cup was gradual
and the plant recovered its turgor, avoiding permanent deleterious alterations in the cellular metabolism, even from a limited
cowpea-growth ψm. 相似文献
13.
14.
Chitwadee Phithakrotchanakoon Ratama Daduang Arinthip Thamchaipenet Thidarat Wangkam Toemsak Srikhirin Lily Eurwilaichitr Verawat Champreda 《Applied microbiology and biotechnology》2009,82(1):131-140
A polyhydroxyalkanote depolymerase gene from Thermobifida sp. isolate BCC23166 was cloned and expressed as a C-terminal His6-tagged fusion in Pichia pastoris. Primary structure analysis revealed that the enzyme PhaZ-Th is a member of a proposed new subgroup of SCL-PHA depolymerase
containing a proline–serine repeat linker. PhaZ-Th was expressed as two glycosylated forms with apparent molecular weights
of 61 and 70 kDa, respectively. The enzyme showed esterase activity toward p-nitrophenyl alkanotes with V
max and K
m of 3.63 ± 0.16 μmol min−1 mg−1 and 0.79 ± 0.12 mM, respectively, on p-nitrophenyl butyrate with optimal activity at 50–55°C and pH 7–8. Surface plasmon resonance (SPR) analysis demonstrated that
PhaZ-Th catalyzed the degradation of poly-[(R)-3-hydroxybutyrate] (PHB) films, which was accelerated in (R)-3-hydroxyvalerate copolymers with a maximum degradation rate of 882 ng cm−2 h−1 for poly[(R)-3-hydroxybutyrate-co-3-hydroxyvalerate] (12 mol% V). Surface deterioration, especially on the amorphous regions of PHB films
was observed after exposure to PhaZ-Th by atomic force microscopy. The use of P. pastoris as an alternative recombinant system for bioplastic degrading enzymes in secreted form and a sensitive SPR analytical technique
will be of utility for further study of bioplastic degradation. 相似文献
15.
Symptoms of fairy rings caused by Lepista sordida have been reported on Zoysiagrass (Zoysia spp.) turf maintained at fairway height (2 cm), but not on bentgrass (Agrostis spp.) maintained at putting green height (0.5 cm). The mycelia of this fungus inhabit primarily the upper 0–2 cm layer of
the soil extending into the thatch. To compare conditions for the mycelial growth in Z. matrella turf to those in A. palustris turf, we examined the effects of nutrients, temperature, water potential, and pH in the field as well as in the laboratory.
Greater growth of the mycelia was observed in medium that included hot water extracts from soil of the 0–1 cm zone in Z. matrella turf compared to that from A. palustris. The upper soil layer in Z. matrella turf contained more organic matter from clippings than that in A. palustris. The temperature and water potential of the 0–2 cm soil zone in Z. matrella turf were also more favorable for the mycelial growth. The soil pH values of this zone in Z. matrella turf were less favorable compared to A. palustris but within the range for accelerating mycelial growth.
Part of this study was presented orally at the 46th meeting of the Mycological Society of Japan in 2002 相似文献
16.
Ni Chen Yan Liu Xin Liu Juan Chai Zhong Hu Guangqin Guo Heng Liu 《Plant Molecular Biology Reporter》2009,27(3):321-333
17.
Sumita Kumari Prabhjeet Singh Sneh L. Singla-Pareek Ashwani Pareek 《Molecular biotechnology》2009,42(2):195-204
18.
Abstract Gas exchange and growth of beech seedlings planted in the understory of a recently thinned pinewood were recorded for 2 years. Relative irradiance was assessed by hemispherical photographs taken just after the thinning. Predawn water potential (pd), daily gas exchange and chlorophyll fluorescence were measured several times during the two growing seasons. Maximum values of photosynthesis (A
max) and stomatal conductance to water vapour (g
wvmax) were established from daily data. Maximum quantum efficiency of PS II was recorded at dawn by taking the variable to maximum chlorophyll fluorescence ratio on dark adapted leaves (F
v/F
m). In the middle of each summer, leaf nitrogen content and leaf mass per area were evaluated, and height growth and basal area increment were recorded at the end of the season. The thinning treatment removed half the trees and generated around 10% more available relative irradiance (GLF). This was followed by an increase in net photosynthesis at saturating PPFD (A
sat) and in maximum stomatal conductance to water vapour (g
wvmax). Moreover, specific leaf mass (SLM) and mass based nitrogen content (Nm) showed higher values for seedlings in the thinned stand. In both years, a positive relationship was established between the area based nitrogen content (Na) and maximum net photosynthesis (A
max). In 1998, a year with a dry summer, seedlings suffered a significant drop in daily A
max irrespective of the thinning regime. This was a response to an increase in stomatal limitation to net photosynthesis, g
wvmax reaching the lowest value on dates with the highest drought. A lack of decrease of Fv/Fm confirmed the absence of significant non-stomatal limitation to A as a consequence of photoinhibition after opening the pinewood. A higher maximum quantum efficiency of open PS II centres (Fv/Fm) was registered in seedlings in the thinned stand. The significance of the differences between the treatments was stronger in the second year after thinning. In 1999, a year with frequent summer storms, water availability increased for seedlings growing under the thinned pinewood. Overall, the reduced pine overstory had a positive effect on physiological responses of beech seedlings, which was translated into improved seedling growth. 相似文献
19.
Xiuping Zou Demou Li Xiaoying Luo Keming Luo Yan Pei 《In vitro cellular & developmental biology. Plant》2008,44(3):169-177
Highly efficient Agrobacterium-mediated transformation of trifoliate orange (Poncirus trifoliata (L.) Raf.) was achieved via indirect shoot organogenesis. Stable transformants were obtained from epicotyl segments infected
with Agrobacterium strain EHA 105 harboring the binary vector pBI121, which contained the neomycin phosphotransferase gene (NPTII) as a selectable
marker and the β-glucuronidase (GUS) gene as a reporter. The effects of regeneration and selection conditions on the transformation
efficiency of P. trifoliata (L.) Raf. have been investigated. A 7-d cocultivation on a medium with 8.86 μM 6-benzylaminopurine (BA)+1.43 μM indole-3-acetic
acid (IAA) was used to improve callus formation from epicotyl segments after transformation. A two-step selection strategy
was developed to select kanamycin-resistant calluses and to improve rooting of transgenic shoots. Transgenic shoots were multiplied
on shoot induction medium with 1.11 μM BA + 5.71 μM IAA. Using the optimized transformation procedure, transformation efficiency
and rooting frequency reached 417% and 96%, respectively. Furthermore, the number of regenerated escape shoots was dramatically
reduced. Stable integration of the transgenes into the genome of transgenic citrus plants was confirmed by GUS histochemical
assay, PCR, and Southern blot analysis. 相似文献
20.
Qingxin Zhao Sheng Yuan Yuling Zhang Hong Zhu Chuanchao Dai Fang Yang Fengmin Han 《World journal of microbiology & biotechnology》2007,23(8):1057-1064
Pectate lyase A (PelA) of Aspergillus nidulans was successfully expressed in Escherichia coli and effectively purified using a Ni2+-nitrilotriacetate-agarose column. Enzyme activity of the recombinant PelA could reach 360 U ml−1 medium. The expressed PelA exhibited its optimum level of activity over the range of pH 7.5–10 at 50°C. Mn2+, Ca2+, Fe2+, Mg2+ and Fe3+ ions stimulated the pectate lyase activity, but Cu2+ and Zn2+ inhibited it. The recombinant PelA had a V
max of 77 μmol min−1 mg−1 and an apparent K
m of 0.50 mg ml−1 for polygalacturonic acid. Low-esterified pectin was the optimum substrate for the PelA, whereas higher-esterified pectin
was hardly cleaved by it. PelA efficiently macerated mung bean hypocotyls and potato tuber tissues into single cells. 相似文献