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排序方式: 共有190条查询结果,搜索用时 15 毫秒
1.
2.
侵染香蕉的黄瓜花叶病毒株系的形态和生物学特征 总被引:4,自引:0,他引:4
对香蕉花叶病广东三个代表分离物的形态和生物学特征进行了较为全面的研究。在六种鉴别寄主上,斑驳类(MM)和断续条纹类(BS)分离物侵染较多的寄主种类诱导较为严重的症状,连续条纹类(CS)分离物侵染能力较弱。电镜观察表明:BS、CS和MM三个代表分离物的粒子呈球状、其粒子直径分别为22.5、24.3和27nm,纯化的病毒粒子电泳相对迁移率分别为0.72、0.56和0.51,在西葫芦上的增殖速度:不管在子叶或真叶,都是MM最快、BS次之、CS最慢。从西葫芦接种叶运转出接种叶的速度:MM和BS相似、CS明显较慢。在烟草上,三个分离物的运转速度和增殖速度以MM最快、BS次之、CS最慢;而且在烟草上随着接种后时间的延长,三个分离物除MM维持高浓度的时间较长外,BS和CS的都很短。在西葫芦和烟草上提纯产量,MM类最多、BS类次之、CS类最低。 相似文献
3.
Bang An Xingrong Hou Yunfeng Guo Shixue Zhao Hongli Luo Chaozu He Qiannan Wang 《Fungal biology》2019,123(5):423-430
Plant pathogens employ effectors as molecular weapons to manipulate host immunity and facilitate colonization. Fusarium oxysporum f. sp. cubense is the agent of wilt disease in banana plantlets and four races of the pathogen have been identified based on the cultivar specificity. A total of 9 SIX genes have been detected in the genome of Foc TR4 and 6 genes detected in Foc1. Among these SIX genes, SIX2 and SIX8 are only detected in Foc TR4, not identified in Foc1. Expression profiles analysis revealed that SIX genes of Foc TR4 are highly induced after inoculation to Cavendish banana plantlets. Virulence analysis of the SIX2 and SIX8 knock-out mutants showed that SIX8 is required for the virulence of Foc TR4 while SIX2 has no obvious functions. Over expression of SIX8-FLAG proteins in the SIX8 knock-out mutant partly restored the virulence. Western blot analysis suggested that SIX8 could be secreted into the extracellular space and a signal peptide resided the N-terminal polypeptide sequence. This study provides some clues for further research on mechanism of SIX8 in regulating virulence of Foc TR4. 相似文献
4.
Studies on a Nigerian isolate of banana streak badnavirus: I. Purification and enzyme linked immunosorbent assay 总被引:2,自引:0,他引:2
A Nigerian isolate of banana streak badnavirus (BSV) was purified and a polyclonal antiserum was produced in mice. The antiserum titre was between 1:10 000 and 1:40 000 in enzyme linked immunosorbent assay (ELISA), and showed a good specificity to BSV antigens. Comparative tests were carried out to determine the sensitivity and reliability of BSV antigen detection by double antibody sandwich (DAS)-ELISA, triple antibody sandwich (TAS)-ELISA, antigen coated plate (ACP)-ELISA, and protein-A coated antibody sandwich (PAS)-ELISA. TAS-ELISA using rabbit polyclonal antiserum to trap BSV and mouse polyclonal antiserum to detect the virus particles, was more sensitive than ACP-ELISA and PAS-ELISA and detected BSV in plant extracts from both symptomatic and some asymptomatic plants. However, immunosorbent electron microscopy detected more BSV-infected plants from asymptomatic plant samples than did TAS-ELISA. Results of this study showed that detection of BSV antigens in sap extracts by TAS-ELISA was most efficient with symptomatic tissues which occurred most frequently in the ‘cool rainy’ season. This suggests that for more reliable BSV-indexing of field samples, tissue sampling should be done during the rainy season when most BSV-infected plants express severe symptoms. 相似文献
5.
Lakshmanan Venkatachalam R. V. Sreedhar Neelwarne Bhagyalakshmi 《Plant Growth Regulation》2007,51(3):193-205
Use of high levels of growth regulators during micropropagation results in undesirable clonal variability in important commercial
crops such as banana. The present study investigated the effects of high levels of cytokinins on micropropagation in banana
(genotype AAB), and the genetic stability of plantlets was assessed using RAPD and ISSR markers. Cytokinins, such as BA and
kinetin were added to the routine shoot multiplication medium at concentrations up to 10 mg l−1. After 12 weeks of culture involving three subcultures, the maximum number of shoot buds were produced in cultures receiving
either 5 mg l−1 BA (80 shoot buds) or 4 mg l−1 kinetin (62 shoot buds). Certain morphological abnormalities observed during proliferation of shoot buds in vitro were not
observed during acclimatization ex vitro. To check the genetic stability, RAPD and ISSR profiles of micropropagated plantlets
obtained from different cytokinin-treatments were compared with control microplants maintained on MS medium as well as the
field-grown mother plant. A total of 50 RAPD and 12 ISSR primers resulted in 625 distinct and reproducible bands. Thus a total
of 17,400 bands were generated showing homogeneous RAPD and ISSR patterns. Band intensity histogram of each gel confirmed
their monomorphic nature with no genetic variation in all the plantlets analysed. Based on these results a protocol for high
rate shoot multiplication was worked out leading to uniform shoot production. 相似文献
6.
Akello J Dubois T Gold CS Coyne D Nakavuma J Paparu P 《Journal of invertebrate pathology》2007,96(1):34-42
Beauveria bassiana is considered a virulent pathogen against the banana weevil Cosmopolites sordidus. However, current field application techniques for effective control against this pest remain a limitation and an alternative method for effective field application needs to be investigated. Three screenhouse experiments were conducted to determine the ability of B. bassiana to form an endophytic relationship with tissue culture banana (Musa spp.) plants and to evaluate the plants for possible harmful effects resulting from this relationship. Three Ugandan strains of B. bassiana (G41, S204 and WA) were applied by dipping the roots and rhizome in a conidial suspension, by injecting a conidial suspension into the plant rhizome and by growing the plants in sterile soil mixed with B. bassiana-colonized rice substrate. Four weeks after inoculation, plant growth parameters were determined and plant tissue colonization assessed through re-isolation of B. bassiana. All B. bassiana strains were able to colonize banana plant roots, rhizomes and pseudostem bases. Dipping plants in a conidial suspension achieved the highest colonization with no negative effect on plant growth or survival. Beauveria bassiana strain G41 was the best colonizer (up to 68%, 79% and 41% in roots, rhizome and pseudostem base, respectively) when plants were dipped. This study demonstrated that, depending on strain and inoculation method, B. bassiana can form an endophytic relationship with tissue culture banana plants, causing no harmful effects and might provide an alternative method for biological control of C. sordidus. 相似文献
7.
Anna?Lucea Carlos M.?DuarteEmail author Susana?Agustí Hilary?Kennedy 《Biogeochemistry》2005,73(2):303-323
The dynamics of the nutrient pools and their stoichiometry as well as their control by ecosystem metabolism (benthic and planktonic)
and benthic–pelagic exchanges (sedimentation rates and sediment waterfluxes) were examined in the Mediterranean littoral (Blanes
Bay, NE Spain). Dissolved organic nitrogen comprised about half of the nitrogen present in the water column and the carbon
pool was dominated by the inorganic pool (95% of the carbon present in the water column). The dissolved and particulate organic
pools were deficient in P relative to C and N, indicating a rapid recycling of P from organic matter. The pelagic compartment
was heterotrophic, supported by significant allochthonous inputs of land material, which also contributed greatly to the sedimentary
inputs (37% of total sedimenting carbon). In contrast, the benthic compartment was autotrophic, with the excess net benthic
community production balancing the deficit in pelagic community production, leading to metabolic equilibrium at the station
studied. Sedimentary inputs of nitrogen, phosphorus and silicon exceeded the benthic release, indicating that the benthic
compartment acted as a sink for nutrients, consistent with its autotrophic nature. Carbon inputs to the benthic compartment
also exceeded requirements, due to the allochthonous subsidies to the system, so that the benthic compartment stored or exported
organic carbon.
An erratum to this article can be found at . 相似文献
8.
Banana streak virus (BSV) is a significant constraint to banana production and genetic improvement. It is necessary to develop and use BSV detection strategies that are both reliable and sensitive for the management of the virus. A loop‐mediated isothermal amplification (LAMP) assay was developed and evaluated for the detection of BSV. Four primers matching a total of six sequences of the conserved ORF III polyprotein genes were synthesized for developing a specific and sensitive LAMP for DNA extracts from field‐infected banana plants. LAMP assay could detect as low as 1 pg/μl template DNA. Test results of all field samples collected from different regions of South China showed that LAMP is more sensitive than PCR. This relatively simple and sensitive technique showed excellent potential with field‐collected samples and for routine screening of tissue culture materials in South China. 相似文献
9.
Michael W. Bairu Wendy A. Stirk Karel Doležal Johannes van Staden 《Plant Cell, Tissue and Organ Culture》2008,95(3):373-379
The effect of the cytokinins mT (meta-topolin), mTR (meta-topolin riboside), MemT (meta-methoxy topolin) and MemTR (meta-methoxy topolin riboside) on micropropagation of banana cultivars ‘Williams’ and ‘Grand Naine’ was studied and compared to
BA (6-benzylaminopurine). In vitro cultures, at the third sub-culture level, were purchased from African Biotechnologies (Pty)
Ltd., South Africa. These were then sub-cultured on MS media containing 7.5, 15 and 30 μM of all the cytokinins tested. Results
recorded after 6 weeks of growth demonstrated that there were statistically significant differences between the parameters
analyzed for the treatments. Superior multiplication rates were recorded for mT and mTR treatments. This result was consistent when compared to BA at 22.2 μM (previously published standard concentration). Contrary
to previous findings with other species, these cytokinins inhibited rooting. The effect on somaclonal variation was not significantly
different when BA, mT and mTR were tested at the seventh multiplication cycle for ‘Williams’ banana. These results support the possible use of topolins
as an alternative to BA for Cavendish banana tissue culture. The role of these cytokinins on somaclonal variation however,
requires a more stringent investigation as the results obtained in this investigation could have been influenced by carry-over
effects from the initial cultures. 相似文献
10.
Gamal A A Elbadri Paul De Ley Lieven Waeyenberge Andy Vierstraete Maurice Moens Jacques Vanfleteren 《International journal for parasitology》2002,32(2):199-205
Restriction fragment length polymorphism and direct sequencing of the internal transcribed spacer rDNA region of 19 isolates of Radopholus similis yielded significant diversity, both among isolates and within some individuals. Restriction fragment length polymorphism with HaeIII, AluI and Tru9I yielded two sets of patterns. Digestion with RsaI revealed one or two supernumerary bands in single nematodes from five isolates, and sequencing confirmed microheterogeneity in four of these. Phylogenetic analysis grouped most isolates closely together, except for the five isolates with additional bands for RsaI. Our data reveal more population structure than previously found and lend further support to the synonymy of R. similis and 'Radopholus citrophilus'. 相似文献