共查询到20条相似文献，搜索用时 15 毫秒
1.
Summary Twenty three accessions of nine Portuguese cabbage and kale land races from different geographic origins were tested at the seedling stage for resistance to several important brassica diseases. Resistance to downy mildew (Peronospora parasitica), expressed as necrosis of the cotyledon mesophyll, was found in all the accessions. Type A resistance to cabbage yellows (Fusarium oxysporum f. sp. conglutinans race 1) was present in most of the landraces. Resistance to clubroot (Plasmodiophora brassicae race 6) was found in one accession of the Portuguese tree kale. High resistance to blackleg (Leptosphaeria maculans) and white rust (Albuco candida) was not detected, although several accessions showed 20 to 30% of plants with intermediate expression of resistance. All Portuguese cole accessions were susceptible to blackrot (Xanthomonas campestris pv. campestris). 相似文献
2.
Summary Fifty-six landraces of Portuguese coles (Brassica oleracea l.), representing fourteen morphotypes, were screened for resistance to Leptosphaeria maculans at the cotyledon stage. Three isolates of the pathogen belonging to three pathogenicity groups were used in the screening. The mean disease interaction phenotype of the B. oleracea landraces with the L. maculans isolates confirmed their differences in pathogenicity. When compared to pathogenicity grouping using a B. napus differential set, a different classification was observed on B. oleracea for the three L. maculans isolates, suggesting possible differences in the genetic interaction between the two plant species and the pathogen. Most of the Portuguese cole landraces were found to be susceptible to all three isolates of L. maculans, although a few have shown intermediate interaction phenotype. Some accessions, on the other hand, elicit a differential reaction with the three isolates tested, and can be further selected to be used in host differential sets or in breeding for resistance to black leg.Fifty-four landraces of Portuguese coles, representing eleven morphotypes, were also screened in the field for resistance to Xanthomonas campestris pv. campestris. A good level of resistance to the bacterium was found in several of the morphotypes.Accessions of the Penca type, particularly, were identified as highly resistant. Landraces belonging to the same Portuguese cole group presented a similar range of mean interaction phenotype with the bacterium. Some Portuguese landraces of B. oleracea are potential sources for use in breeding programs for black rot resistance. 相似文献
3.
Summary A morphological study was carried out to determine the relationships among Portuguese cole landraces using 58 accessions belonging to: (i) Portuguese Tronchuda cabbage (Brassica oleracea var. tronchuda Bailey syn. var. costata De Candolle, Couve Tronchuda); (ii) Portuguese Galega kale (B. oleracea var. acephala De Candolle, Couve Galega); and (iii) other economically less important coles such as Algarve cabbages (B. oleracea var. capitata L., Couve do Algarve or B. oleracea var. sabauda L., Couve Repolho-lombarda do Algarve). The cole accessions were collected from the growers, studied under field conditions during two consecutive years, and characterized using 46 morphological characters from seedling stage to ripe silique. Morphological data were analysed by numerical taxonomy techniques using UPGMA (Unweighted Pair Group Method Using Arithmetic Averages) and by principal component analysis (PCA). Phenograms based on correlation and distance coefficients showed the existence of 8 main groups (A-H). Five of these groups correspond to Tronchuda cabbage landraces: (A) Couves de Trás-os-Montes; (B) Couves do Minho; (C) Couves from Central Portugal; (D) Couve Portuguesa; (E) Couves from Southern inland Portugal. The three other groups correspond to: (F) cabbages; (G) miscellaneous coles; and (H) Galega kales. Landrace groups are primarily associated with morphological differences among accessions and secondly with accession geographical origin. The interannual character variation did not affect the clustering patterns of the accessions and therefore the stability of landrace classification. PCA was congruent with the landrace groups defined by the phenograms and gave supplementary information on the usefulness of the characters for the definition of the various groups. 相似文献
4.
Summary Morphological characters, nuclear RFLPs, and isozyme analysis were used to study the similarity between 32 Portuguese Tronchuda cabbage and Galega kale landraces, and some cabbage cultivars traditionally grown in Portugal. Forty-six morphological characters observed in two consecutive years, RFLP data from 55 nuclear probes, detecting 291 polymorphic nuclear DNA restriction fragments, and allelic frequencies in 21 putative loci, generated by nine isozymes, were analyzed by the unweighted pair group method, using arithmetic averages (UPGMA), in order to present the results in the form of a phenogram. The three methods resulted in different clustering patterns of the 32 cole accessions. Morphological characters gave consistent clustering according to the traditional landrace definition and denomination, producing clear separation between Tronchuda cabbages and Galega kales. RFLPs were unable to separate Tronchuda cabbages from Galega kales and defined five landrace groups corresponding to their geographic origins rather than to their morphological similarities. Isozymes showed poor accession discrimination and an intermediate clustering pattern with some accessions being clustered according to their geographic origins and others according to their morphological similarities. Portuguese Tronchuda cabbages and Galega kales constitute a distinct and relatively homogenous group within Brassica oleracea, sharing the same genetic background. It is concluded that Portuguese coles have evolved independently from a common ancestor to the present cultivated forms. Portugal should be considered as an important region of domestication of specialized leafy coles. 相似文献
5.
Downy mildew, incited by Peronospora parasitica (Pers.: Fr.) Fr., is a destructive disease of broccoli (Brassica oleraceaL., Italica Group). Resistant cultivars represent a desirable control method to provide a practical, environmentally benign,
and long-term means of limiting damage from this disease. Doubled-haploid (DH) lines developed by us exhibit a high level
of downy mildew resistance at the cotyledon stage. To determine the mode of inheritance for this resistance, a resistant DH
line was crossed to a susceptible DH line to make an F1, from which F2 and backcross (BC) populations were developed. All populations were evaluated for response to artificial inoculation with
P. parasitica at the cotyledon stage. All F1 plants (including reciprocals) were as resistant as the resistant parent, indicating no maternal effect for this trait. F2 populations segregated approximately 3resistant to 1 susceptible, BC populations using the resistant parent as the recurrent
parent contained all resistant plants, and the BC to the susceptible parent segregated 1 resistant to 1 susceptible. These
results indicate that resistance is controlled by a single dominant gene. This gene should be easily incorporated into F1 hybrids and used commercially to prevent downy mildew at the cotyledon stage.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
6.
Summary Melon germplasm was screened for cucumber green mottle mosaic virus (CGMMV), powdery mildew (Sphaerotheca fuliginea), downy mildew (Pseudoperonospora cubensis) and Fusarium wilt (Fusarium oxysporum f. sp. melonis) resistance under artificial conditions except downy mildew for which screening was done under natural epiphytotic conditions. High level resistance to all the four diseases was not recorded in any of the collections tested. Nevertheless, ertheless, resistance to three diseases was located in three germplasm. Wild Cucumis species C. figarei exhibited absolute resistance to CGMMV and Fusarium wilt and high level resistance to downy mildew. Phoot or snapmelon (Cucumis melo var. momordica) — a non-dessert from of Indian origin—was highly resistant to downy mildew and resistant to CGMMV and medium resistant to Fusarium wilt. Iroquois was resistant to powdery mildew and medium resistant to downy mildew and CGMMV. 相似文献
7.
Expression of resistance to downy mildew at cotyledon and adult plant stages in Brassica oleracea L.
This research compared the expression of resistance to downy mildew at cotyledon and adult plant stages in seven Brassica oleracea genotypes against two P. parasitica isolates of different virulence. Seven day old seedlings were dual inoculated under controlled environment by depositing
two 10 μl droplets of a spore suspension of a different isolate on each cotyledon and the interaction phenotype (IP) evaluated
7 days later using a 0–5 scale of increasing susceptibility. The seedlings were transplanted to 16 cm pots and grown in the
greenhouse for 110 days (15 to 28 leaves). Adult plants were tested using a single leaf inoculation method that allowed the
same plant to be simultaneously inoculated with the two P. parasitica isolates. Leaves were scored 10 days after inoculation using a 0–5 scale of increasing susceptibility. The inoculation of
the same plant with the two isolates produced different combinations of cotyledon (CT) and adult-plant (AP) interaction-phenotype
according to the genotype. CrGC 3.1 was susceptible at CT and AP stages, ‘Algarvia’ resistant at CT and AP stages, and broccoli
‘A’ susceptible at CT and resistant at AP stage against the two isolates. ‘Murciana’ and broccoli ‘B’ were differential at
CT and AP stages. Savoy and Shetland cabbages were differential at CT stage and resistant to both isolates as adult plants.
Cotyledon resistance could not be used to predict adult-plant resistance since the two types of resistance were very poorly
correlated. Resistance can be race specific either at cotyledon or at adult-plant stage.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
Discovery,characterization and exploitation of Mlo powdery mildew resistance in barley 总被引：14，自引：0，他引：14
I. Helms Jørgensen 《Euphytica》1992,63(1-2):141-152
Summary Mlo resistance to barley powdery mildew is a relatively new kind of resistance. It was originally described in a powdery mildew resistant barley mutant in 1942 and has been mutagen-induced repeatedly since then. About 1970 it was also recognized in barley landraces collected in Ethiopia in the 1930s. It is unique in that 1) Mlo resistance does not conform to the gene-for-gene system; 2)mlo genes originating from different mutational events map as non-complementing recessive alleles in one locus; 3) all alleles confer the same phenotype, though with small quantitative differences; 4) it is effective against all isolates of the pathogen; and 5) the resistance is caused by rapid formation of large cell wall appositions at the encounter sites preventing penetration by the fungus. Powdery mildew isolates with elevated Mlo aggressiveness have been produced on barley in the laboratory, but have not been found in nature. Mlo resistance is considered very durable. The exploitation of Mlo resistance has been hampered by pleiotropic effects of themlo genes, vix. necrotic leaf spotting and reduced grain yield, but they have been overcome by recent breeding work. During the 1980s Mlo-resistant spring barley varieties have become cultivated extensively in several European countries, in 1990 on about 700,000 ha. 相似文献
9.
Downy mildews cause considerable damage to maize (Zea mays L.) worldwide, particularly in the tropical Asia. We have evaluated a set of 42 tropical/sub-tropical maize inbred lines
developed in different countries in Asia (India, Thailand and Philippines), and Mexico, for analysing the genetic variability
for resistance to sorghum downy mildew [Peronosclerospora sorghi; SDM] and Rajasthan downy mildew [P. heteropogoni; RDM]. Experiments were carried out in replicated trials under artificial infection in field conditions against SDM and RDM
at Mandya in Karnataka, India, and Udaipur in Rajasthan, India, respectively, during 1999 and 2000. The study resulted in
identification of five inbred lines offering consistent and strong resistance to both SDM and RDM, while several inbred lines
revealed resistance only to RDM. It was also revealed that the SDM-resistant inbreds are invariably resistant to RDM, while
the RDM-resistant inbreds might show differential responses to the SDM. The maize inbred lines identified in this study with
broad-spectrum resistance to downy mildews could be potentially useful for basic and applied research work on downy mildews
in tropical Asia.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
Pearl millet (Pennisetum glaucum (L.) R. Br.) cultivars for marginal, arid environments need to combine the adaptation to stress conditions of indigenous landraces with an improved yield potential and disease resistance, to allow them to both perform well in farmers fields and to meet the requirements for cultivar release. This paper evaluates landrace-based topcross hybrids (adapted landraces crossed on high-yielding male-sterile lines), as a quick and efficient way of achieving this objective. Topcross hybrids showed a consistent increase in biomass production across all test environments, including the harsh arid zone environments. Depending upon the plant type of the male-sterile used to make the hybrid, this was expressed as increased grain yield only, or increased grain and fodder yields. The downy mildew (Sclerospora graminicola) reaction of the topcross hybrids was determined by the reaction of the male-sterile line used, with the resistant male-sterile producing resistant topcross hybrids and vice-versa. Topcrossing adapted landraces on high-yielding male-sterile lines thus provides an opportunity to improve disease resistance and grain and/or fodder yields, with no apparent loss of adaptation to the marginal environments in which the landraces have evolved.ICRISAT Journal Article no. 1575 相似文献
11.
Summary RFLPs were used to study the genetic relationships of 31 Portuguese coles (Brassica oleracea L.) representing the different ecotypes or landraces grown in Portugal. Other cole crops such as Jersey kale, Chinese kales, common cabbages, broccolis and cauliflower, two nine-chromosome wild species, and one accession of turnip also were included to determine the evolutionary relationships of Portuguese coles to other related coles. Principal coordinates and cluster analyses were conducted using a package of computer programs and RFLP data from 55 nuclear DNA probes, detecting 291 polymorphic restriction fragments. The results showed that the 48 accessions clustered into five groups: (a) a dispersed group with turnip and the wild brassicas; (b) Chinese kales; (c) broccolis and cauliflower; (d) a disperse group including Algarve and Jersey kales, thousand head kale, cabbages, and savoy cabbage; (e) a large and compact group containing all Portuguese tronchuda cabbages and kales. This unique and closely related group containing Portuguese tronchuda cabbages and kales could be further divided into five subgroups corresponding to the major areas of cultivation. The phenetic groupings of Portuguese tronchuda cabbages and kales based on RFLP data corresponded more with their geographic origins (collecting sites) than with their morphological similarities. A mechanism involving geographic isolation and frequent intercrossing within local areas is proposed to explain genetic relationships among Portuguese tronchuda cabbages and kales. 相似文献
12.
Jerzy H. Czembor 《Euphytica》2002,125(3):397-409
Seventy-five barley landraces from Morocco were tested for resistance to powdery mildew and a number of different resistance
genes were detected. Thirty-five isolates of Blumeria graminis f. sp. hordei and the Pallas isoline differential set were used. Isolates used in the experiment had virulences corresponding to all major
resistance genes used in Europe. Forty-four of the tested landraces showed resistant reactions. From each of these landraces,
one to five resistant plants were selected and 92 single plant lines were created. Six lines selected from 3landraces were
assumed to carry the mlo gene but they were discarded after microscopic investigation. Seventeen lines were tested in the seedling stage with 17isolates
and another 69 lines were tested with 23 differential isolates. These lines showed 71 reaction spectra to isolates of powdery
mildew. Eight lines (9%), 255-3-3, 282-3-4, 286-1-1, 294-2-3,294-2-4, 295-1-2, 308-1-2 and 327-2-1, selected from 7 landraces
showed resistance to all isolates. Seventy-eight lines (90%) showed a resistant infection type 2with more than 50% of the
isolates used. In most of the selected lines (86%) unknown genes, alone or in combination with known specific resistance genes,
were detected. Four different resistance alleles (Mlat, Mla6, Mla14 and Mla1) were postulated to be present in the tested lines. The most common was Mlat, which was postulated in 35 (41%) lines. The use of newly identified sources of powdery mildew resistance in barley breeding
is discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
13.
A total of 240 kale, 38 cabbage and 126 winter cauliflower French landraces from the B. oleracea genepool of INRA were assessed for resistance to clubroot caused by Plasmodiophora brassicaeWoron. Two French isolates of the pathogen (K and SJ) were used in the experiments under controlled conditions. The reaction
of the 126 cauliflower accessions to naturally occurring clubroot was also evaluated in field trials. Kales exhibited considerable
variation for expression of disease resistance and high levels of resistance were found in several accessions. In this group,
single resistant plants were observed in most of the morphological types and from quite different geographical origins. Cabbage
accessions were moderately to highly susceptible to both isolates. All cauliflower populations proved to be highly susceptible
to K isolate and moderately susceptible to SJ isolate. In field trials, cauliflowers were also severely infected. Two lines
selected from a resistant kale population were highly resistant against a large range of pathotypes of the pathogen. These
lines presented a sufficient level of resistance to be directly useful in the breeding program in order to develop cauliflower
and broccoli hybrids resistant to clubroot.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
Summary A geographically representative selection of germplasm of Beta vulgaris, section Beta has been assessed for characteristics important in sugarbeet breeding, including downy mildew resistance, resistance to aphid colonisation and infection by the beet virus yellow complex. The occurrence of maintainer lines for cytoplasmic male-steriles was also investigated. Desirable qualities were found in some accessions, including nothern European wild vulgaris ssp. maritima and some old multigerm cultivars of fodder beets. 相似文献
15.
Pea bacterial blight (Pseudomonas syringae pv. pisi) has long been known to be present in pea growing areas of Spain and to cause serious crop losses, although there is no published
record of its occurrence. A collection of 16 isolates from a winter pea trial in Valladolid in 1991 which were shown in this
study to be P.s. pv. pisi races 4 and 6 would appear to be the first published record of the disease in Spain. This occurrence of races 4 and 6 is
the same as reported for winter-sown peas in the South of France. Ten Pisum sativum landraces from different geographical areas of Spain and considered to be representative of the traditional pea crop, were
tested for resistance to seven races of P.s. pv. pisi. Seedlings of each landrace were stem inoculated with the type strain of each race in a glasshouse. Resistance exhibited
by the different landraces mainly conformed to those previously described in pea cultivars indicating various combinations
of the main resistance genes: R3, R2+4, R3+4 and R2+3+4. R3 was the most frequent R gene, being present in all landraces.
R4 was present in four and R2 in three of the landraces tested. Variation for resistance within landraces was limited except
for landrace accessions ZP-0102, ZP-0109 and ZP-0137 which also showed variation for morphological traits. The resistance
responses of landrace ZP-0109 were difficult to interpret, but suggested a genetic mixture with some evidence of less well
documented R genes, R5 and/or R6, and possibly some unknown resistance to race 6.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
The objective of this study was to determine the mode of inheritance of field resistance to downy mildew (Peronospora parasitica (Pers. ex Fr.) Fr.) in broccoli (Brassica oleracea var.italica) at the adult plant stage. The F1, F2 and F3 progeny of resistant and susceptible plants of broccoli were tested in the field under natural infection, in central Portugal,
from August to December in two successive years. The plants were evaluated for resistance to downy mildew at maturity using
a five-class scale of increasing susceptibility to the disease, which took into account the number of infected leaves and
the size of the sporulating lesions. The F1 was completely resistant, the F2 segregated a clear 3 resistant: 1susceptible and the F3 confirmed the F2 segregation, which suggests a dominant character controlled by a single locus. This resistance has good potencial for direct
use in commercial broccoli breeding or for transfer to other Brassica vegetables.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
17.
A Fusarium sp. root pathogen of lupin is the causal agent of the most important disease that affects the cultivation of white lupin
(Lupinus albus L.) in Egypt. The aim of our research was to investigate whether host resistance to Fusariumroot disease was available in Egyptian landraces ofLupinus albus. Five Fusarium isolates collected from white lupin samples in Egypt were tested with an Egyptian landrace and a French cultivar. The most
aggressive isolate was used to screen an additional 15 Egyptian landraces, two cultivars released in Egypt after selection
among landraces, one Polish cultivar, and two French cultivars. The assessment of host response to Fusarium was performed in a field, and under controlled conditions in a greenhouse pot experiment. Most landraces and the two Egyptian
cultivars showed better resistance with good accordance between field and pot experiment. This experiment showed that Egyptian
genetic resources of white lupin possess partial resistance to Fusarium root rot. Egyptian germplasm may be an alternative genetic source for incorporating partial resistance to Fusarium root rot into the breeding pools.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
Summary Inheritance of downy mildew (Peronospora parasitica) resistance in three resistant x susceptible crosses, one susceptible x susceptible and one resistant x resistant cross were studied in Indian cauliflower (Group III) over the two years (1990 and 1991). No significant difference was observed between the years for various estimates and hence pooled data are presented. Downy mildew resistance in crosses cc×HR 5-4 and 3-5-1-1×244 (R×S) is governed by single dominant gene PPA3 but in cross cc×244 (R×S), recessive epistasis was observed. The resistance level was not improved in both the cc×3-5-1-1 (R×R) and 244×267-6-9 (S×S) crosses. Exploitation of downy mildew resistance from cc and 3-5-1-1 in F1 hybrid is explained in detail. 相似文献
19.
The relationship between resistance in seedlings, young and adult plants is studied for the pathosystem Brassica oleracea–Hyaloperonospora parasitica. Genotypes identified in the laboratory as resistant or susceptible or exhibiting a differential reaction to a selection
of H. parasitica isolates were tested in 1997–1999 in seedbeds and fields under natural infestation. Isolates tested in the laboratory were
grouped in five pathotypes, of which four were presented by isolates from Brittany, France. Genotypes susceptible to all pathotypes
in the laboratory were also susceptible in the seedbed and field tests, while genotypes expressing a differential response
to pathotypes were either resistant or susceptible. Accessions Everest, DEGC, ESPG and RS1105 exhibiting resistance to all
pathotypes except I, were resistant in all environments and remained resistant in 2000–2002. Pathotype I was not prevailing
in the field and results support the hypothesis that accessions resistant under laboratory conditions will be resistant under
field conditions, provided the same pathotypes are present under the laboratory and field conditions. 相似文献
20.
O. E. Scholten A. W. van Heusden L. I. Khrustaleva K. Burger-Meijer R. A. Mank R. G. C. Antonise J. L. Harrewijn W. Van haecke E. H. Oost R. J. Peters C. Kik 《Euphytica》2007,156(3):345-353
Downy mildew resistance originating from Allium roylei Stearn provides a complete resistance to onions and is based on one, dominant gene. Since A. roylei can successfully be hybridized with onion (A. cepa L.), a breeding scheme aimed at the introgression of this gene was initiated ca. 20 years ago. Several setbacks in this programme were encountered, firstly the identified molecular marker linked to the downy mildew resistance locus became increasingly difficult to use and finally lost its discriminating power and secondly the final step, making homozygous introgression lines (ILs), turned out to be more difficult then was hoped. GISH analysis showed that the chromosomal region harbouring the resistance locus was the only remaining piece of A. roylei in the nuclear background of onion and it also confirmed that this region was located on the distal end of chromosome 3. It was hypothesized that some factor present in the remaining A. roylei region was lethal when homozygously present in an onion genetic background. The identification of an individual with a smaller and more distally located introgression fragment and homozygous ILs in its progeny validated this hypothesis. With the help of these nearly isogenic lines four AFLP® markers closely linked to the resistance gene were identified, which can be used for marker-aided selection. The introduction of downy mildew resistance caused by Peronospora destructor into onion is a significant step forward in the development of environmentally-friendly onion cultivars. 相似文献