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1.
Shatrupa Ray Surendra Singh B. K. Sarma H. B. Singh 《Journal of Plant Growth Regulation》2016,35(2):401-412
The potential of endophytic bacteria to act as biofertilizers and bioprotectants has been demonstrated, and considerable progress has been made in explaining their role in plant protection. In the present study, three endophytic bacterial strains (BHU 12, BHU 16 isolated from the leaves of Abelmoschus esculentus, and BHU M7 isolated from the leaves of Andrographis paniculata) were used which displayed high sequence similarity to Alcaligenes faecalis. The biofilm formation ability of these endophytic strains in the presence of okra root exudates confirms their chemotactic ability, an initial step for successful endophytic colonization. Further, reinoculation of spontaneous rifampicin-tagged mutants into okra seedlings revealed a CFU count above 105 cells g?1 of all three endophytic strains in root samples during the first 15 days of plant growth. The CFU count increased up to 1013 by 30 days of plant growth, followed by a gradual decline to approximately 1010 cells g?1 at 45 days of plant growth. Systemic endophytic colonization was further supported by 2, 3, 5-triphenyl tetrazolium chloride staining and fluorescence imaging of ds-RED expressing conjugants of the endophytic strains. The strains were further assessed for their plausible in vivo and in vitro plant growth-promoting and antagonistic abilities. Our results demonstrated that the endophytic strains BHU 12, BHU 16, and BHU M7 augmented plant biomass by greater than 40 %. Root and shoot lengths of okra plants when primed by BHU 12, BHU 16, and BHU M7 increased up to 34 and 14.5 %, respectively. The endophytic isolates also exhibited significant in vitro antagonistic potential against the collar rot pathogen Sclerotium rolfsii. In summary, our results demonstrate excellent potential of the three endophytic bacterial strains as biofertilizers and biocontrol agents, indicating the possibility for use in sustainable agriculture. 相似文献
2.
Karolina Vrandecic Drazenka Jurkovic Luca Riccioni Jasenka Cosic Tomislav Duvnjak 《Mycopathologia》2010,170(1):51-60
Sunflower (Helianthus annuus) stem canker caused by Diaporthe helianthi is one of the most important sunflower diseases in Croatia. Until recently, sunflower was the only known host for D. helianthi. In our research carried out in the area of Eastern Croatia, isolates of Diaporthe/Phomospis were collected from Xanthium italicum, X. strumarium and Arctium lappa. Using morphological, cultural and molecular ITS rDNA data, isolates from these weeds were identified as D. helianthi. The following isolates were used in the pathogenicity test: one isolate originated from sunflower (Su5/04), three from X. italicum (Xa2, Xa3 and Xa5), two from X. strumarium (Xa9 and Xa12), one from Xanthium sp. (Xa13) and one from A. lappa (Ar3). According to the results, it was determined that isolate Xa5 (originated from X. italicum) was the most pathogenic to sunflower stems. The average length of the lesion was 11.3 cm. The lowest level of pathogenicity
was found in Xa9 (isolated from X. strumarium). The length of the lesion was 0.1 cm. 相似文献
3.
Auxin regulates diverse molecular and physiological events at the cellular and organismal levels during plant growth and development
in response to environmental stimuli. It acts either through distinct signaling pathways or in concert with other growth hormones.
Its biological functions are adjusted by modulating biosynthesis, conjugate formation, and polar transport and distribution.
Several tryptophan-dependent and -independent auxin biosynthetic pathways have been proposed. Recent studies have shown that
a few flavin monooxygenase enzymes contribute to the tryptophan-dependent auxin biosynthesis. Here, we show that activation
of a flavin monooxygenase gene YUCCA7 (YUC7), which belongs to the tryptophan-dependent auxin biosynthetic pathway, enhances drought resistance. An Arabidopsis activation-tagged mutant yuc7-1D exhibited phenotypic changes similar to those observed in auxin-overproducing mutants, such as tall, slender stems and curled,
narrow leaves. Accordingly, endogenous levels of total auxin were elevated in the mutant. The YUC7 gene was induced by drought, primarily in the roots, in an abscisic acid (ABA)-dependent manner. The yuc7-1D mutant was resistant to drought, and drought-responsive genes, such as RESPONSIVE TO DESSICATION 29A (RD29A) and COLD-REGULATED 15A (COR15A), were up-regulated in the mutant. Interestingly, whereas stomatal aperture and production of osmoprotectants were not discernibly
altered, lateral root growth was significantly promoted in the yuc7-1D mutant when grown under drought conditions. These observations support that elevation of auxin levels in the roots enhances
drought resistance possibly by promoting root growth. 相似文献
4.
5.
C. A. Martínez A. M. Giulietti J. Rodríguez Talou 《Plant Cell, Tissue and Organ Culture》2011,104(1):91-100
Hypericum perforatum L. (St. John’s wort) produces a number of phytochemicals having medicinal, anti-microbial, anti-viral and anti-oxidative
properties. Plant extracts are generally used for treatment of mild to medium cases of depression. Plant regeneration can
be achieved in this species by in vitro culture of a variety of explants. However, there are no reports of regeneration from
petal explants. In this report plant regeneration from petal explants of St. John’s wort was evaluated. Petals of various
ages were cultured on agarized Murashige and Skoog 1962 (MS) medium supplemented with auxin and cytokinin (kinetin), maintained in the dark and callus and shoot regeneration determined
after 28 days. At an auxin to cytokinin ratio of 10:1, callus and shoot formation were induced by all levels of indole-3-acetic
acid (IAA), indole-3-butyric acid (IBA) and 1-naphthaleneacetic acid (NAA), while 2,4-dichlorophenoxyacetic acid (2,4-D) induced
only callus formation. The optimum level of auxin for shoot regeneration was 1.0 and 0.1 mg/l kinetin, where the regeneration
frequency was 100 percent for all three auxins. The highest number of shoots per explant (57.4 and 53.4) was obtained with
IAA and IBA, respectively. In the absence of auxin, kinetin levels of 0.1 and 0.25 mg/l induce callus and shoot formation
at low frequency but not at lower levels. Callus and shoot formation did not occur in the absence of growth regulators. Petal-derived
shoots were successfully rooted on half-strength MS medium without a requirement for exogenous auxin and flowering plants
were established under greenhouse conditions. From these results it can be concluded that auxin type is a critical factor
for plant regeneration from petal explants of Hypericum perforatum and there is no absolute requirement for high levels of cytokinin. 相似文献
6.
7.
Salinity adversely affects plant growth and development. Halotolerant plant-growth-promoting rhizobacteria (PGPR) alleviate
salt stress and help plants to maintain better growth. In the present study, six PGPR strains were analyzed for their involvement
in salt-stress tolerance in Arachis hypogaea. Different growth parameters, electrolyte leakage, water content, biochemical properties, and ion content were analyzed in
the PGPR-inoculated plants under 100 mM NaCl. Three bacterial strains, namely, Brachybacterium
saurashtrense (JG-06), Brevibacterium
casei (JG-08), and Haererohalobacter (JG-11), showed the best growth of A. hypogaea seedlings under salt stress. Plant length, shoot length, root length, shoot dry weight, root dry weight, and total biomass
were significantly higher in inoculated plants compared to uninoculated plants. The PGPR-inoculated plants were quite healthy
and hydrated, whereas the uninoculated plant leaves were desiccated in the presence of 100 mM NaCl. The percentage water content
(PWC) in the shoots and roots was also significantly higher in inoculated plants compared to uninoculated plants. Proline
content and soluble sugars were significantly low, whereas amino acids were higher than in uninoculated plants. The MDA content
was higher in uninoculated plants than in inoculated plants at 100 mM NaCl. The inoculated plants also had a higher K+/Na+ ratio and higher Ca2+, phosphorus, and nitrogen content. The auxin concentration was higher in both shoot and root explants in the inoculated plants.
Therefore, it could be predicted that all these parameters cumulatively improve plant growth under saline conditions in the
presence of PGPR. This study shows that PGPR play an important role in inducing salinity tolerance in plants and can be used
to grow salt-sensitive crops in saline areas. 相似文献
8.
Zhehao Chen Mengting Li Ye Yuan Jiangqin Hu Yanjun Yang Jiliang Pang Lilin Wang 《Plant Cell, Tissue and Organ Culture》2017,131(1):107-118
Auxin receptors TIR1/AFBs play an essential role in a series of signaling network cascades. These F-box proteins have also been identified to participate in different stress responses via the auxin signaling pathway in Arabidopsis. Cucumber (Cucumis sativus L.) is one of the most important crops worldwide, which is also a model plant for research. In the study herein, two cucumber homologous auxin receptor F-box genes CsTIR and CsAFB were cloned and studied for the first time. The deduced amino acid sequences showed a 78% identity between CsTIR and AtTIR1 and 76% between CsAFB and AtAFB2. All these proteins share similar characteristics of an F-box domain near the N-terminus, and several Leucine-rich repeat regions in the middle. Arabidopsis plants ectopically overexpressing CsTIR or CsAFB were obtained and verified. Shorter primary roots and more lateral roots were found in these transgenic lines with auxin signaling amplified. Results showed that expression of CsTIR/AFB genes in Arabidopsis could lead to higher seeds germination rates and plant survival rates than wild-type under salt stress. The enhanced salt tolerance in transgenic plants is probably caused by maintaining root growth and controlling water loss in seedlings, and by stabilizing life-sustaining substances as well as accumulating endogenous osmoregulation substances. We proposed that CsTIR/AFB-involved auxin signal regulation might trigger auxin mediated stress adaptation response and enhance the plant salt stress resistance by osmoregulation. 相似文献
9.
Kuvalekar Aniket Pawar Pankaj Khare Ankita Gandhe Kanchanganga Harsulkar Abhay 《Plant Cell, Tissue and Organ Culture》2008,94(1):101-104
Ravenelia esculenta Naras. and Thirum. is a rust, pathogenic to Acacia eburnea Willd. The infection leads to hypertrophy changing the morphology with bizarre shapes of plant organs. Healthy and infected
tissues were subjected to extraction of IAA and indole derivatives and were estimated by spectrophotometric methods. The hypertrophy
produced was presumed to be due to increase in the indole-3-acetic acid (IAA) content in the infected tissue, however, the
amount of IAA in infected tissues decreased with the progression of disease. Concomitantly, the infected tissue showed the
presence of a novel, slow migrating, indole derivative on TLC. Cultured shoot tips of Withania somnifera were dosed with the methanolic extract of the infected hypertrophied tissue (MEHT) (0.25, 0.5, 0.75, 1.00 and 1.25 mg/l).
The stimulation in shoot growth along with profuse rooting was observed in a dose dependent manner with maximum at 1.00 and
1.25 mg/l concentration. 相似文献
10.
Ferreira LQ Avelar KE Vieira JM de Paula GR Colombo AP Domingues RM Ferreira MC 《Current microbiology》2007,54(5):348-353
The Bacteroides genus, the most prevalent anaerobic bacteria of the intestinal tract, carries a plethora of the mobile elements, such as
plasmids and conjugative and mobilizable transposons, which are probably responsible for the spreading of resistance genes.
Production of β-lactamases is the most important resistance mechanism including cephalosporin resistance to β-lactam agents
in species of the Bacteroides fragilis group. In our previous study, the cfxA gene was detected in B. distasonis species, which encodes a clinically significant broad-spectrum β-lactamase responsible for widespread resistance to cefoxitin
and other β-lactams. Such gene has been associated with the mobilizable transposon Tn4555. Therefore, the aim of this study was to detect the association between the cfxA gene and the presence of transposon Tn4555 in 53 Bacteroides strains isolated in Rio de Janeiro, Brazil, by PCR assay. The cfxA gene was detected in 11 strains and the Tn4555 in 15. The transposon sequence revealed similarities of approximately 96% with the B. vulgatus sequence which has been deposited in GenBank. Hybridization assay was performed in attempt to detect the cfxA gene in the transposon. It was possible to associate the cfxA gene in 11 of 15 strains that harbored Tn4555. Among such strains, 9 presented the cfxA gene as well as Tn4555, but in 2 strains the cfxA gene was not detected by PCR assay. Our results confirm the involvement of Tn4555 in spreading the cfxA gene in Bacteroides species. 相似文献
11.
Summary An efficient in vitro propagation system was developed for Arnebia euchroma, an important Chinese traditional medicinal plant. The present study utilized thidiazuron (TDZ) for the induction of shoot
organogenesis on cotyledon and hypocotyl explants. The maximal number of shoots was obtained on the modified Linsmaier and
Skoog (LS) medium supplemented with 1.0 mgl−1 (4.5 μM) TDZ for 12d on cotyledon explants (8.6 shoots per cotyledon explant). Other cytokinins (kinetin and 6-benzyladenine) and
auxin (α-naphthaleneacetic acid) were not efficient in inducing regeneration on cotyledon explants. Browning of the basal
portion of the subcultured shoots could be significantly reduced when they were cultured on the modified LS medium supplemented
with 100 mgl−1 (33.3 μM) polyvinylpyrrolidone. Well-developed shoots formed roots on the same medium containing 1.0 mgl−1 (4.9 μM) indole-3-butyric acid. The efficient regeneration protocol reported here provides an important means of micropropagation
of this plant. Furthermore, this protocol is essential to future genetic improvement of plants via transformation protocols. 相似文献
12.
S Ramadasappa AK Rai RS Jaat A Singh R Rai 《World journal of microbiology & biotechnology》2012,28(4):1681-1690
Tomato (Lycopersicon esculentum) is important widely grown vegetable in India and its productivity is affected by bacterial wilt disease infection caused
by Ralstonia solanacearum. To prevent this disease infection a study was conducted to isolate and screen effective plant growth promoting rhizobacteria
(PGPR) antagonistic to R. solanacearum. A total 297 antagonistic bacteria were isolated through dual culture inoculation technique, out of which forty-two antagonistic
bacteria were found positive for phlD gene by PCR amplification using two primer sets Phl2a:Phl2b and B2BF:BPR4. The genetic diversity of phlD
+ bacteria was studied by amplified 16S rDNA restriction analysis and demonstrated eleven groups at 65% similarity level. Out
of these 42 phlD
+ antagonistic isolates, twenty exhibited significantly fair plant growth promoting activities like phosphate solubilization
(0.92–5.33%), 25 produced indole acetic acid (1.63–7.78 μg ml−1) and few strains show production of antifungal metabolites (HCN and siderophore). The screening of PGPR (phlD
+) for suppression of bacterial wilt disease in glass house conditions was showed ten isolated phlD
+ bacteria were able to suppress infection of bacterial wilt disease in tomato plant (var. Arka vikas) in the presence R. solanacearum. The PGPR (phlD
+) isolates s188, s215 and s288 was observed to be effective plant growth promoter as it shows highest dry weight per plant
(3.86, 3.85 and 3.69 g plant−1 respectively). The complete absence of wilt disease symptoms in tomato crop plants was observed by these treatments compared
to negative control. Therefore inoculation of tomato plant with phlD
+ isolate s188 and other similar biocontrol agents may prove to be a positive strategy for checking wilt disease and thus improving
plant vigor. 相似文献
13.
Under the present study, an attempt was made to characterize rhizobacteria i.e. Pseudomonas and Bacillus species isolated from rhizosphere of carnation to evaluate their growth promoting effect on carnation so as to select and
develop more efficient indigenous plant growth promoting and disease suppressing bioagents of specific soil type and specific
plant type. Maximum strains of Pseudomonas and Bacillus sp. showed significant antimicrobial activities against most of the microorganisms tested. On the basis of in vitro antagonistic
activities, the best strains were selected and used in field trial to study the influence of these strains on the growth of
carnation. Results have shown marked effect on growth parameters and disease incidence has also been reduced significantly. 相似文献
14.
<Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated genetic transformation of <Emphasis Type="Italic">Perilla frutescens</Emphasis> 总被引:3,自引:0,他引:3
A reproducible plant regeneration and an Agrobacterium tumefaciens-mediated genetic transformation protocol were developed for Perilla frutescens (perilla). The largest number of adventitious shoots were induced directly without an intervening callus phase from hypocotyl explants on MS medium supplemented with 3.0 mg/l 6-benzylaminopurine (BA). The effects of preculture and extent of cocultivation were examined by assaying -glucuronidase (GUS) activity in explants infected with A. tumefaciens strain EHA105 harboring the plasmid pIG121-Hm. The highest number of GUS-positive explants were obtained from hypocotyl explants cocultured for 3 days with Agrobacterium without precultivation. Transgenic perilla plants were regenerated and selected on MS basal medium supplemented with 3.0 mg/l BA, 125 mg/l kanamycin, and 500 mg/l carbenicillin. The transformants were confirmed by PCR of the neomycin phosphotransferase II gene and genomic Southern hybridization analysis of the hygromycin phosphotransferase gene. The frequency of transformation from hypocotyls was about 1.4%, and the transformants showed normal growth and sexual compatibility by producing progenies. 相似文献
15.
Phenylpropanoids, flavonoids and plant growth regulators in rice (Oryza sativa) variety (UPR 1823) inoculated with different cyanobacterial strains namely Anabaena oryzae, Anabaena doliolum, Phormidium fragile, Calothrix geitonos, Hapalosiphon intricatus, Aulosira fertilissima,
Tolypothrix tenuis, Oscillatoria acuta and Plectonema boryanum were quantified using HPLC in pot conditions after 15 and 30 days. Qualitative analysis of the induced compounds using reverse
phase HPLC and further confirmation with LC-MS/MS showed consistent accumulation of phenolic acids (gallic, gentisic, caffeic,
chlorogenic and ferulic acids), flavonoids (rutin and quercetin) and phytohormones (indole acetic acid and indole butyric
acid) in rice leaves. Plant growth promotion (shoot, root length and biomass) was positively correlated with total protein
and chlorophyll content of leaves. Enzyme activity of peroxidase and phenylalanine ammonia lyase and total phenolic content
was fairly high in rice leaves inoculated with O. acuta and P. boryanum after 30 days. Differential systemic accumulation of phenylpropanoids in plant leaves led us to conclude that cyanobacterial
inoculation correlates positively with plant growth promotion and stress tolerance in rice. Furthermore, the study helped
in deciphering possible mechanisms underlying plant growth promotion and stress tolerance in rice following cyanobacterial
inoculation and indicated the less explored avenue of cyanobacterial colonization in stress tolerance against abiotic stress. 相似文献
16.
Tocci N Simonetti G D'Auria FD Panella S Palamara AT Valletta A Pasqua G 《Applied microbiology and biotechnology》2011,91(4):977-987
Hypericum perforatum is a well-known medicinal plant which contains a wide variety of metabolites, including xanthones, which have a wide range
of biological properties, including antifungal activity. In the present study, we evaluated the capability of roots regenerated
from calli of H. perforatum subsp. angustifolium to produce xanthones. Root biomass was positively correlated with the indole-3-butyric acid concentration, whereas a concentration
of 1 mg l−1 was the most suitable for the development of roots. High auxin concentrations also inhibited xanthone accumulation. Xanthones
were produced in large amounts, with a very stable trend throughout the culture period. When the roots were treated with chitosan,
the xanthone content dramatically increased, peaking after 7 days. Chitosan also induced a release of these metabolites into
the culture. The maximum accumulation (14.26 ± 0.62 mg g−1 dry weight [DW]) and release (2.64 ± 0.13 mg g−1 DW) of xanthones were recorded 7 days after treatment. The most represented xanthones were isolated, purified, and spectroscopically
characterized. Antifungal activity of the total root extracts was tested against a broad panel of human fungal pathogen strains
(30 Candida species, 12 Cryptococcus neoformans, and 16 dermatophytes); this activity significantly increased when using chitosan. Extracts obtained after 7 days of chitosan
treatment showed high antifungal activity (mean minimum inhibitory concentration of 83.4, 39.1, and 114 μg ml−1 against Candida spp., C. neoformans, and dermatophytes, respectively). Our results suggest that root cultures can be considered as a potential tool for large-scale
production of extracts with stable quantities of xanthones. 相似文献
17.
Clare Annabel Bowen-O’Connor John Hubstenberger Cynthia Killough Dawn Marie VanLeeuwen Rolston St. Hilaire 《In vitro cellular & developmental biology. Plant》2007,43(1):40-50
Bigtooth maple (Acer grandidentatum) is a promising ornamental tree that is not widely used in managed landscapes. Tissue culture has not been used successfully
to propagate this taxon. We cultured single- and double-node explants from greenhouse-grown, 2-y old seedlings of bigtooth
maples, which are indigenous to New Mexico, Texas, and Utah, on Murashige–Skoog (MS), Linsmaier–Skoog (LS), Driver–Kuniyuki
Walnut (DKW), and Woody Plant (WPM) tissue culture media. Media affected shoot proliferation (P = 0.0242) but the zone of explant origin (P = 0.7594) did not. After four 30-d subcultures, explants on DKW media and WPM media produced 3.6 and 3.5 shoots per explant,
respectively. Sprouting rates were highest on DKW, making DKW the best overall media for shoot proliferation. Double-node
microshoots were rooted in vitro on DKW containing indole acetic acid (IAA). Microshoots represented six genotypes from three locations within Texas and New
Mexico. Rooting percentage increased up to 15% as IAA concentration increased (P = 0.0040). There was 100% survival of rooted microshoots in vented Phytatrays containing one perlite: one peat moss (v/v). We conclude that DKW can be used to proliferate microshoots, and IAA induces rooting in microshoots of bigtooth maple. 相似文献
18.
Two oligosaccharides, a heptasaccharide (HS) and an octasaccharide (OS), isolated from Paris polyphylla var. yunnanensis, stimulated the growth and saponin accumulation of Panax ginseng hairy roots at 5–30 mg l−1. HS and OS at 30 mg l−1, fed separately to hairy root cultures at 10 days post-inoculation, increased the root biomass dry weight by more than 70%
to ∼20 g l−1 from 13 g l−1 and the total saponin content of roots by more than 1-fold to ∼3.5% from 1.6% (w/w). The results suggest that the two oligosaccharides
may have plant growth-regulatory activity in plant tissue cultures. 相似文献
19.
The phytohormone auxin regulates many aspects of plant growth and development. Auxin often acts distantly from the site of
its biosynthesis and this long-distance-transported auxin is well known to play a critical role in eliciting physiological
responses including regulating root development. Auxin can be produced in roots, yet the function of locally synthesized auxin
in root growth is unclear. The major auxin in plants, indole 3-acetic acid (IAA), is mainly synthesized through tryptophan
(Trp)-dependent pathways that require pyridoxal phosphate (an active form of vitamin B6)-dependent enzymes. We previously reported that the Arabidopsis vitamin B6 biosynthesis mutant pdx1 has stunted root growth although the underlying cause is unknown. Here we showed that the pdx1 root is deficient in auxin biosynthesis. By reciprocal grafting of pdx1 and the wild type, we demonstrated that the stunted root growth in pdx1 is caused by a locally generated signal(s) in roots. To test whether auxin might be one such signal, the auxin responsive
DR5::GUS reporter was introduced into the mutant. The DR5::GUS activity in pdx1 root tips was greatly reduced compared with that in the wild type although the auxin response was unaltered. pdx1 also suppresses the root hair growth defects in the auxin overproduction mutant yucca. These data indicate that pdx1 is impaired in Trp-dependent auxin biosynthesis, which may contribute to the short-root phenotype of pdx1. We suggest that locally synthesized auxin may play a critical role in postembryonic root growth. 相似文献