摘要:

The polyacrylamide gel electrophoresis (PAGE) test of Morris&Smith (1977) was evaluated for detection of potato spindle tuber viroid (PSTV) in breeding material. Number, density and mobility of nucleic acid bands in the electropherograms were influenced by genotype and growing temperature. So direct testing of genotypes was not reliable. After an intermediate viroid multiplication in tomato host plants at about 30oC and high irradiance, PSTV was reliably detectable with PAGE in inocula of potato samples of diverse origin. A 4‐week incubation period proved to be suitable for inocula with low and high concentrations of a mild strain of PSTV (m‐PSTV) as well as a severe strain of PSTV (s‐PSTV). If incidence of PSTV is expected to be low, testing can be speeded up by bulking samples. With the combined tomato‐intermediate/ PAGE assay, one m‐PSTV or one s‐PSTV infected leaf disk in 200 healthy ones was consistently detectable. Occasionally gels with a nucleic acid band of about the same relative mobility as the viroid band were found. Evidence that these bands were not caused by viroid is presented. A procedure to resolve such questionable test results is described. Infectivity of s‐PSTV was higher than that of m‐PSTV. Concentration of viroids in the inoculum influenced appearance of mild or severe symptoms and the rate of sym

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1982.tb01806.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Connu en Europe depuis plus ďun siécle,Heterodera avenaeest le plus commun des nématodes à kystes des céréales. C'est une espéce trés polymorphe, présentant de multiples races ou pathotypes caractérisés par leur cycle biologique et leur gamme ďhôtes, qui apparaît endémique en Europe et dans le bassin Méditerranéen et que ľon a retrouvée en Australie, en Inde et de façon plus localisée en Amérique du Nord. Dans les zones géographiques reconnues contaminées, de 20 à 60 % des champs inventoriés apparaissent habituellement infestés. Les dommages, trés variables selon les régions, peuvent étre considérables, de ľordre de 50 % de la récolte dans les cas graves et certainement de quelques pour cent àľéchelle de pays entiers. Le blé et ľorge sont les cultures les plus touchées et le maïs, atteint de maniére trés variable selon les régions, peut se révéler, soit un bon hóte, soit un mauvais hôte pour le ravageur. Les dommages peuvent aussi être aggravés par des affections cryptogamiques. Les généticiens s'efforcent de rechercher et de créer des cultivars résistants ou tolérants dans de nombreux pays mais ceux‐ci ne sont généralement valables que pour certains des nombreux pathotypes existants. Ce probléme, sous‐estimé tant que ľon a cultivé des cultivars à rendement moyen ou faible, apparaît au contraire trés grave en présence de cultivars nouveaux beaucoup plus performants, mais aussi beaucoup plus vulnérables. ďautres espéces ďHeteroderaont été isolées depuis une dizaine ďannées;certaines, telles qu'H. mani,ne présentent pas ďintérêt économique, mais ďautres, commeH. hordecalisen Europe du Nord ouH. latiponsdans le bassin Méditerranéen ne doivent pas être négligées car elles peuvent se substituer àH. avenaeen présence de céréales

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1982.tb01807.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Cyst nematodes are sedentary parasites with limited host ranges and co‐evolution with circumscribed host groups is believed to result in species complexes. A scheme for this process is given. TheHeterodera avenaegroup is such a complex parasitising cereals and grasses. Although the group includes ten nominal species, onlyH. mani, H. avenaeandH. avenaepathotype 3 present taxonomic problems of immediate relevance in agriculture. Application of a multivariate technique, principal co‐ordinate analysis, to second‐stage juvenile characters indicates thatH.avercae pathotype 3 is as distinct fromH. avenaeasH. arenaria,an accepted species in theH. avenaegroup. In contrast there are difficulties with juvenile and cyst morphology in distinguishingH. manifromH. a

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1982.tb01808.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

A survey of cereal and grass cyst nematodes in the Federal Republic of Germany revealed thatHeterodera avenaeis the most widely distributed heteroderid species and common mainly in areas with light sandy soils and intensive cereal cultivation. The so‐called ≪race 3 ≫ was recovered several times, and other populations differing morphologically from ≪ typical ≫H. avenaewere found.H. hordecalis, H. bifenestra, H. mani, H. iriandPunctodera punctatawere also recovered in many parts of the country. In arable soils these species constituted only 7 % of all records of cereal and grass cyst nematodes, whereas they prevailed in grassland, forests and other habitats, where they amounted to almost 80 % of the records. 93 % of allH. avenaerecords came from agricultural soils, but only 21 % of the records of the five other species.H. hordecalisandH. bifenestraare obviously of no economic importan

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1982.tb01809.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

In south‐eastern Australia, where large areas of cereal crops are grown in a Mediterranean climate, yield loss caused byHeterodera avenaeis generally more severe than in Northern Europe. This appears to be due to differences in seasonal cropping patterns and the stages of crop growth when roots are exposed to larvae. Field observations and laboratory experiments show that, in Australia, crops ≪ sown early ≫, in late autumn, are less damaged than those ≪ sown late ≫. This is explained by the times of emergence and population density of larvae, by the nematode‐fungus interaction and by the environmental conditions affecting plant growth, rather than by differences in the nematode or in hos

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1982.tb01810.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The cereal cyst nematode(Heteroderaavenae) was discovered in New Zealand in 1975 on wheat and oats. It was not at that time causing appreciable economic losses in yield, presumably because usual management practice incorporated a good crop rotation with lucerne. However, now that the growing of cereals has become more profitable, farmers are tending to grow consecutive cereal crops and more damage fromH. avenaeis being experienced. On one farm, up to 9%of an oat crop was lost due to this nematode. The biotype has not yet been determined.

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1982.tb01811.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Second‐stage juveniles of heteroderid species often present more reliable diagnostic characters than cysts. For identification of European cereal and grass cyst nematodes, size and position of the phasmids, swelling of the cuticle behind the lip region, expression of the lateral fields, shape and size of the stylet knobs and measurements of, for example, the tail and the hyaline tail portion are useful. A key presented, based on larval characters, allows identification of seven European cereal and grass cyst nematode species and their distinction from other European heteroderids not reproducing on Gramineae. Species identification is often difficult in theHeterodera avenae/H. manicomplex and evidence exists that additional species are present within this grou

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1982.tb01812.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Heterodera avenaeandHeterodera latiponsare widespread on cereals in Bulgaria and mixed populations are encountered.H. avenaepopulations reach their highest point on barley after ten years cereal monoculture. The two‐field crop rotation maize/cereals keeps the population at a low level.H. avenaehas been found on most cultivars of wheat and barley cultivated in Bulgaria. The author had detected two previously unreported hosts:Agrostis capillarisandCynosurus cristatus.The most appropriate conditions for infection on cereals occur in April. Nematode development starts in April and finishes in the first half of June.Nematophthora gynophilaparasitizes about 20% of the cysts, whileCatenaria auxiliaryand Lagenidiaceous fungi do so to a lesser exten

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1982.tb01813.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Several types ofHeteroderaspp. belonging to the≪ avenae ≫group have been found in Spain on cereal crops and wild Gramineae. The morphological differences between them relate to the colour of the cysts, presence or absence and consistency of the subcrystalline layer, presence or absence and shape of the ≪ underbridge ≫ in the vulvar cone, length of the 2nd‐stage larvae and shape of their stylet knobs. The value of these characters in the diagnosis of these species is discussed together with the identity of

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1982.tb01814.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

On a étudié par l'électrophorèse la variabilityé de certains enzymes avec l'idée de trouver des caractéres plus commodes pour la distinction des pathotypes. Les premiers resultats font apparaître qu'Heterodera avenae, contrairement à ce qui a été observé chez le genre voisinMeloidogyne, est très polymorphe pour les quatre premiers enzymes déjà analyses, soit: deux estérases, la malate déhydrogénase (MDH) et les phosphatases acides. Les differences d'une population à l'autre semblent pour l'instant plutôt se situer au niveau du nombre d'allèles presents et de leurs fréquences respectives dans chacune d'elles. Différents phénomènes biologiques ont été parallèlement mis en évidence comme l'≪ inbreeding ≫à faible densité de population ou la fécondation effectiv

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1982.tb01815.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY