摘要:

Of the 44 currently accepted species ofPhytophthora, 18 have been reported in the Mediterranean area. The status of each is briefly reviewed. On citrus,P. citrophthoraandP. nicotianaevar.parasiticaare mainly responsible for foot rot and gummosis, and in additionP. hibernalis, P. syringae, P. cifricolaandP. cactorumfor brown rot of fruits. The incidence of these species is closely linked to their temperature requirements. The use of sour orange as a resistant rootstock has long provided satisfactory control of foot rot and gummosis, while chemical treatments are effective against brown rot. However, there are indications that, with changingcultural practices, the resistance of sour orange is less well expressed, and the species is incidentally also susceptible to citrus tristeza closterovirus. Alternative rootstocks are therefore being sought.

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01173.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Of the approximately 50 recognizedPhytophthoraspp., more than half have not been reported to cause root rot or crown rot. Some well‐known phytophthora root and crown rots have still not been diagnosed in many regions or countries in the world. It seems likely that this arises mainly from use of inappropriate isolation media and diagnostic procedures. Thus, various root disorders of tree and horticultural crops have been attributed to other pathogens or to abiotic causes, and found to be due toPhytophthoraspp. only when proper isolation techniques involving baiting and selective media were used. These special techniques, however, are still not widely used by many diagnosticians and pathologists today. It seems that most pathologists lack training and specific knowledge onPhytophtohoradiseases and tools for their study. They are often unaware of the importance of these fungi in causing below‐ground infections, or of the unique nature of their biology, soil ecology and pathology in relation to root and crown rot development. It is hoped that wider use of special isolation techniques in routine diagnoses in the future will result in an increase in the frequency of reports of occurrence of phytophthora root and crown rots of woody perennials around the wo

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01174.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Huit espèces differentes dePhytophthorasont capables de parasiter les agrumes en donnant des attaques sur racines, sur tronc et branches charpentières (gommose) et sur fruits (pourriture brune), y compris après récolte. Les trois espèces les plus importantes sontP. citrophthora, P. nicotianaevar.parasiticaetP. palmivora, avec une prédominance qui varie selon les régions climatiques. La taxonomie classique repose sur la morphologie des spores sexuées et asexuées, parfois sur celle du thalle, et aussi sur des critères physiologiques: homoou hétérothallisme, températures cardinales de croissance. Sur ces bases, l'appartenance spécifique des isolats peut le plus souvent être déterminée, mais certaines ambiguïtés demeurent. La validité des taxons ne peut être éprouvée que par l'étude de populations d'isolats et en ayant recours à des critères supplémentaires, de nature biochimique. L'analyse des protéines solubles totales ou d'isoenzymes, d'origine mycélienne ou extra‐cellulaire, séparées par éectrophorèse ou isofocalisation, a maintenant bien prouvé son intérêt. De nouvelles méthodes, s'adressant non plus à l'expression des gènes mais à leur organisation, sont en train de voir le jour. L'enjeu n'est pas seulement taxonomique; il concerne aussi la st

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01175.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

To identify 11Phytophthoraisolates obtained from lemon, peach and apple trees, and from strawberry plants, in the Mediterranean region of Turkey, protein, acetylesterase, peroxidase and catalose band patterns of these isolates and the same bands of 10 identified isolates ofPhytophthora citrophthora, P. cinnamamiandP. cactarumwere compared. These 11 regional isolates were identified on the basis of the similarity of their protein and enzyme band patterns to those of identifiedPhytophthoraisolates. It was concluded that protein band patterns could be used for identification ofPhytophthoraspecies. With enzyme band patterns, however, it may be possible to identify at species level but it is more practical to use this method only for identification of subspecies.

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01176.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Total proteins (both native and denatured) and three isoenzyme systems (esterases, malate dehydrogenases, superoxide dismutases) were analysed for eightPhytophthoraspecies and for eight strains ofP. nicotianae.The results obtained showed low intraspecific variability (62‐100% of similarity index) forP. nicotianaeand allowed the characterization ofP. capsici, cinnamomi, cryptogea, megakarya, megasperma, nicotianae, palmivoraandcitrophthoraby the polyacrylamide gel electrophoretic profiles of native proteins and isoenzymes. The interspecific variability between these eight species is high (27‐49% of similarity index). The results obtained support the use of these macromolecular criteria as an aid to the identification ofPhytophthora

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01177.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Morphological and cultural characters currently used for the classification of species ofPhytophthoraare inadequate to distinguishP. cryptogea, P. drechsleriandP. erythroseptica.In this study isolates of the above‐mentioned species, including type and/or authentic cultures ofP. cryptogeaandP. drechsleriwere compared. Morphological and cultural characters, together with electrophoretic patterns of both total mycelial proteins and isozymes (arylesterase and malate dehydrogenase), allowed the distinction ofP. erythrosepticafrom the others. Authentic cultures ofP. cryptogeaandP. drechslerishowed distinctly different electrophoretic patterns of arylesterase and malate dehydrogenase isozymes and of total mycelial proteins. Some Italian isolates previously identified asP. cryptogeaorP. drechslerishowed features of both species, therefore it was impossible to discriminate the two species solely on the basis of the electrophoretic patterns of mycelial protein

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01178.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

La mise en oeuvre simultanée des deux systèmes enzymatiques phosphoglucoisomerase (PGI) de malate déshydrogénase (MDH) semble pennettre une bonne reconnaissance interspécifique dePhytophthora palmivora (sensu stricto), P. megakaryaet deux espèces proches respectivement deP. capsiciet deP. citrophthora, parasites du fruit du cacaoyer. De plus, le nombre de bandes constantes et variables des MDH avecP. megakaryalaisse supposer l'existence chez cette espèce d'au moins quatre populations. AvecP. palmivora, I'hétérozygotie des PGI et la ségrégation obtenue dans la descendance soultvent I'hypothèse d'un‘hybride naturellement sélectionnéà partir d'entités infraspécifiques ayant des relations privilégiées les unes avec les autres. En ce qui concerne le polymorphisme des longueurs de fragments de restriction (RFLP) de I'ADN nucléaire, les profils obtenus avec BAM H1 sont pour I'instant les plus distinctifs. Les mêmes analyses ont été faites sur d'autres espèces dePhytophthora, commeP. nicotianaevar.parasitica, P. cactorum, P. cinnamomi, P. citricola, P. fragariae, P. infestans, P.

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01179.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Mechanisms generating variation inPhytophthoraare assessed. Patterns of inheritance are typically those of a diploid organism. The increasing availability of single gene markers is allowing the breeding system in heterothallic species to be defined. The genetics of virulence and fungicide resistance is summarized; somatic recombination and variation in chromosome number is discussed. Rapid advances in basic genetics, population genetics and evolution are expected through the application of the new techniques for manipulating DNAin vitro.The complexity of the problem is not underestimated.

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01180.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Une prospection a été entreprise dans les plus importantes régions citricoles portugaises afin d'obtenir une information préliminaire sur la population dePhytophthoraspp. parasites des agrumes au Portugal. Au cows de cette prospection cinq espèces ont été isolées et identifiées:P. citricola, P. citrophthora, P. hibernalis, P. nicotianaevar.parasiticaetP. syringae.Leur caracterisation a été effectuée d'après les aspects bio‐morphologiques et éco‐géographiques les plus importants. La population dePhytophthoraspp. inféodées aux agrumes s'est répartie entre une espece majoritaire‐P.citrophthora(60,9%)—et quatre minoritaires: P.citricola(15,2%),P. hibernalis(15,2%),P. n. parasitica(4,3%) etP. syringae(4,3%).P. citrophthoraa été repérée dans tout le territoire continental portugais;P. citricolaetP. hibernalisont été isolées dans les régions du centre et du nord; par contre,P. n. parasitican'existe que dans la région de Sintra (environs de Lisbonne) etP. syringaeque dans la région de Coimbra, montrant une petite dispersion géographique. HormisP. hibernalis, toutes ces espèces ont été sign

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01181.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Effects of irrigation on the dynamics of soil populations ofPhytophthora citrophthorahave been studied in three citrus orchards in East Sicily (Italy). Significant increases of inoculum levels were detected 24 h after irrigation. In one orchard throughout summer, population ofP. citrophthorabeneath the tree canopy was more than 15 propagules g‐1soil, a value which is considered a threshold level for root rot infection

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01182.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY