摘要:

AbstractThe optimum inoculation position on the maize plant, and optimum time of inoculation withStenocarpella maydisfor artificial induction of ear rot were determined in field trials. The placement of a conidial suspension on the shank at silking resulted in the highest incidence ofS. maydisear rot.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01308.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractAn antagonistic effect between the UV‐blue (shorter than 500 nm) and red (longer than 600 nm) wave regions on the induction of phototropic response in conidium germ tubes has been demonstrated in the fungusSeptoria obesa, the causal organism of brown spot disease of cultivated chrysanthemum. Phototropic response of conidium germ tubes was dependent on the ratio of the fluence rates between negative phototropism‐inducing UV‐blue wave region and positive phototropism‐inducing red wave region. Elimination of the UV wave region shorter than 390 nm by an ultraviolet absorbing vinyl film significantly reduced the negative phototropic response of conidium germ tubes and suppressed the invasion of the fungus through the stomata. Thus, a manipulation of the phototropic response of conidium germ tubes by controlling light quality resulted in the suppression of brown spot disease of cultivated chrysa

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01309.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractA tenuivirus, tentatively designated Iranian wheat stripe virus (IWSV), was transmitted by the delphacidUnkanodes tanasijeviciand induced dwarfing, striping and yellowing symptoms in wheat. It could also infect barley, oat, rice, rye, sorghum and a number of other gramineous species. The virus was purified from wheat by chloroform clarification and differential and density‐gradient centrifugation. It formed several layers in density‐gradient columns. Purified virus preparations had a UV absorption spectrum typical of nucleoproteins and contained flexuous supercoils of 8.7 nm and fine filaments of 4.3 nm width. The antiserum produced against the virus reacted with infected plant sap in agar‐gel diffusion and enzyme‐linked immunosorbent assay (ELISA). The virus could be readily detected in individual viruliferous planthoppers by ELISA. IWSV was serologically related to rice hoja blanca virus but not to maize stripe virus. The relationship of IWSV with other tenuiviruses is di

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01310.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractLeaf disks from hop stunt viroid (HSVd)‐infected cucumber plants and healthy controls were culturedin vitrounder different auxin/cytokinin regimes. Amounts of tissue growth and root formation were consistently reduced as a result of HSVd infection. Histological observations indicated that anomalies in the distribution of peripheral meristems and tracheary elements associated with cambial cells might be involved in the hypoplastic syndrome incited by HSV

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01311.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractFatal yellowing is a serious disease of still unknown origin affecting oil palms in several regions of Central and South America. In this study a search for viroids and viroid‐like RNAs in oil palms was performed using two‐dimensional gel electrophoresis and return gel electrophoresis of nucleic acid extracts. Although RNAs showing viroid‐like gel‐electrophoretic properties were detected, the presence of the known viroids was excluded by hybridization experiments using probes specific for potato spindle tuber viroid (PSTVd), coconut cadang‐cadang viroid (CCCVd), orColeus blumeiviroid 1 (CbVd1). By using double‐stranded RNA (dsRNA) specific monoclonal antibodies, which do not react with viroid RNA, we were able to show that oil palm RNAs, migrating like viroids are double‐stranded RNA species. Since the same dsRNA pattern was found in extracts from diseased as well as from healthy oil palms, the dsRNAs can neither be part of the causative agent of fatal yellowing, nor are they associated with the disease. Their possible origin is discussed. In addition to the standard electrophoretic methods, which have been used for identification of viroids and viroid‐like RNAs, we describe additional control experiments to differentiate unequivocally between circular single stranded a

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01312.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe mode of penetration and colonization of stalk, shank and leaf sheath tissues of maize byStenocarpella maydis(=Diplodia maydis) was determined by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) observations. Detached plant tissues, inoculated with a conidial suspension and examined by SEM at various intervals, showed thatS. maydisconidia germinated on all plant material types after 5 h incubation at 30 °C. After 72 h incubation, appressoria had formed at the hyphal tips. Similar observations were recorded on plants inoculated in the glasshouse except that germination was delayed by 7 days after inoculation. TEM studies showed that penetration was affected by a penetration hypha which resulted in the inter‐ and intracellular colonization of the plant tissues. Colonization was accompanied by degradation of cell walls suggesting that host colonization is facilitated by enzyme activi

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01313.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractTubers from somatic hybrids produced by protoplast fusion betweenSolanum brevidens, a diploid, non‐tuber‐bearing wild species, and a tetraploidS. tuberosumshowed resistance to decay caused by soft rotErwinia. Tubers of theS. tuberosumfusion parent and potato cultivar Russet Burbank are susceptible to bacterial soft rot. Tubers of somatic hybrids indicated higher levels of activities of polyphenol oxidase and peroxidase than tubers of the parental line ofS. tuberosumand cultivar Russet Burbank. This is true for intact tubers and also for injured or inoculated tubers.Polish commercial potato cultivars indicated a higher susceptibility to soft rot than somatic hybrids. However, there were some differences in susceptibility to soft rot between Polish commercial potato cultivars, only slight differences were observed in the activities of the polyphenol oxidase and peroxidase between Polish cultivars. A relation between soft rot resistance and the activity of each enzyme was not found for intact, injured or inoculated tissue of commercial cultivars. On the contrary, the activities of both enzymes were significantly higher in the periderm than in the medullary tissue of somatic hybrids, the parental line and the commercial cultiv

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01314.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractIn vitroand greenhouse trials were conducted to elucidate the potential use of extracts of tea and coffee wastes to control plant diseases caused by the bacterial pathogens,Pseudomonas syringaepv.pisi(race 1 and 2) andP. s. pv.phaseolicola(race 1). The antibacterial activity was measured as the diameter of the inhibition zone in agar and also by periodical viable cell counts in laboratory tests. The effect on the hypersensitive reaction and the potential for disease control after leaf infiltration and seed treatment were studied on bean plants in the greenhouse. Results showed that both the tea and coffee extracts possessed antibacterial activity against the three pathogens, but that the effects varied depending on the strain and the test method. Strong reduction of halo blight disease and improvement in plant growth was obtained in presence of the coffee extract. For the halo blight pathogen,P. s. pv.phaseolicola, there was a good correlation between the results from the viable cell count method and the greenhouse tests, but the results from thein vitrostudies did not agree with those from greenhouse as regards theP. s. pv.pisistrains. It is suggested that the component(s) in tea and coffee responsible for controlling the bean pathogen may not be the same as that for the pea pathogens.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01315.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractNine antibiotic producer strains ofErwinia herbicola(=Pantoea agglomerans), belonging to different groups, strongly inhibited growth of 21 streptomycin sensitive strains and 6 streptomycin resistant strains ofE. amylovora.The antibacterial spectra of antibiotics produced by the tested strains ofE. herbicolawere mainly limited toE. amylovoraand related tested species. The tested strains ofE. amylovorathat are resistant to streptomycin did not show cross‐resistance to the different types of antibiotics produced by the tested strains ofE. herbicola.The antibiotics produced by the different tested strains ofE. herbicoladid not exert any activity on tested fungi with the exception that strains Eh 153 and Eh 351 slightly inhibited the growth ofVerticillium dahlia

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01316.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractEleven isolates ofPseudocercosporella herpotrichoideswere obtained from field material of the GramineaeAgropyron repens, Alopecurus myosuroides, Apera spica‐venti, Hordeum vulgareandTriticum aestivum. Four of these isolates belonged to the varietyacuformisand 7 isolates to the varietyherpotrichoidesof the fungus.In a greenhouse experiment, winter wheat was inoculated with these isolates. All isolates were pathogenic on wheat. They differed in virulence, but these differences could not be related to the nature of their original hosts nor to their classification as varietyacuformisorherpotrichoide

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01317.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY