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1.
Summary The interspecific (C. arabica × tetraploid C. canephora) F1 hybrid showed a low but highly variable fertility. An almost complete restoration to normal fertility was observed in individual trees of BC1 and BC2 generations with C. arabica as recurrent parent. From a comparison of various tests of fertility, it was found that pollen viability is a satisfactory measure of fertility. 相似文献
2.
Summary Seeds from open-pollinated flowers collected from hybrids of several Coffea species were analysed for caffeine content. The caffeine content was not always intermediary to that of the parents; higher and lower values were found. Diploid F1 hybrids between accessions of C. eugenioides and C. salvatrix showed the lowest seed caffeine content. Seeds of the tetraploid hybrids C. arabica × C. salvatrix or C. arabica × C. eugenioides hybrids presented low caffeine content. The possibility of breeding coffee to reduce the caffeine content in the seeds by interspecific hybridization of C. arabica with other Coffea species is discussed. 相似文献
3.
Breeding for host resistance to coffee berry disease (CBD) in arabica coffee (Coffea arabica) was initiated some 35–40 years ago in Kenya, Ethiopia and Tanzania in response to severe CBD epidemics. The release of CBD
resistant cultivars to the coffee growers has been in progress since 1985. The resistance of cultivars like Ruiru 11 (Kenya)
and Ababuna (and other cvs in Ethiopia) appears to be of a durable nature, since confirmed cases of a breakdown of host resistance
under field conditions have not been reported over the past 20 years. Host resistance to the hemibiotrophic fungus Colletotrichum kahawae is of a quantitative nature, but nevertheless can be practically complete in some genotypes of arabica coffee. There is still
no consensus on the genetics of CBD resistance, some claiming convincing evidence for oligogenes (1–3 major genes) and others
for polygenes determining CBD resistance. Results from genetic studies with germplasm from the centre of genetic diversity
for C. arabica in Ethiopia are presented here. These together with the recent identification of molecular markers associated with and the
mapping of one major gene, provides additional evidence for oligogenic inheritance of CBD resistance. The development of cultivars
combining yield and quality with durable host resistance to CBD has contributed greatly to increased sustainability of arabica
coffee production in Africa. It has also considerable relevance to arabica coffee in Latin America and Asia, where CBD is
still a quarantine disease but with a risk of becoming endemic one day, just as has happened earlier with coffee leaf rust
(Hemileia vastatrix). 相似文献
4.
Summary Random amplified polymorphic DNA (RAPD) markers have been successfully employed to analyse the genetic diversity among cultivated and subspontaneous accessions of Coffea arabica. The narrow genetic base of commercial cultivars was confirmed. On the other hand, a relatively large genetic diversity was observed within the germplasm collection demonstrating the importance of collecting missions. Results suggested an East-West differentiation in Ethiopia, the primary centre of diversification of C. arabica. The large heterosis effect reported in intergroup hybrids could be related to such genetic differentiation. RAPD method appeared to be effective in resolving genetic variations and in grouping germplasm in C. arabica. 相似文献
5.
Nayani Surya Prakash Marie-Christine Combes Naveen Somanna Philippe Lashermes 《Euphytica》2002,124(3):265-271
S.288 an offspring of a putative spontaneous interspecific hybrid between tetraploid Coffea Arabica (2n = 4x = 44) and diploid C. liberica(2n = 2x = 22) and 17 arabica coffee introgression lines (representing F2 and F4) derived from the cross S.288 x Kent arabica were evaluated for introgression of C. liberica genetic material. In all, 36 AFLP primer combinations were used in the analysis. The AFLP profiles of introgressed lines
were compared to five accessions each of C. arabica and C. liberica. A total of 137 polymorphic bands were scored among the 29 accessions analysed. The introgressed genotypes exhibited 102
marker bands consisting of 65 additional bands and 37missing bands associated with introgression of C. liberica genetic material. C. liberica accessions of EA group (C. liberica var liberica of Guinean origin) seemed to be the likely progenitor in the origin of natural hybrid. Analysis of genetic relationships
in the introgressed lines suggested that introgression was limited to few fragments. Segregation and wide variation in number
of marker fragments in the F2 and F4progenies were attributed to chromosome recombinations. The differences in the level of introgression between introgressed
parent, F2 and F4 groups was not pronounced. Therefore the alien genetic material appeared to be fixed and there was no elimination or counter-selection
over generations, from introgressed parent to F4.In C. arabica accessions, only 35 polymorphic bands were seen confirming the low genetic diversity. On the contrary, although representing
a small amount of alien genome introgression, the Liberica-introgressed genotypes provided notable genetic diversity. Considering
the fact that the diploid species of Coffea constitute a valuable source of genetic diversity, the potential implications of variability generated by Liberica-introgressed
genotypes in C. arabica breeding are discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
6.
Juan Carlos Herrera P. Gabriel Alvarado A. Hernando A. Cortina G. Marie-Christine Combes Gladys Romero G. Philippe Lashermes 《Euphytica》2009,167(1):57-67
The objective of this study was to identify polymorphic molecular markers associated with partial resistance to coffee leaf
rust, Hemileia vastarix. A segregating F
2 population derived from a cross between the susceptible Coffea arabica cv. Caturra and a C. canephora-introgressed Arabica line exhibiting high partial resistance was analyzed. Rust resistance measured as rust incidence (RI)
and defoliation (DEF) was evaluated in field conditions in three consecutive years (2003–2005). During the 2003 season, which
was characterized by favorable conditions for a rust epidemic, the F
2 plants exhibited different levels of resistance ranging from very susceptible (50.1% for DEF and 49.5% for RI) to highly
partial resistance (9.1% for DEF and 3.7% for RI). Molecular analysis enabled identification of seven polymorphic markers
(5 AFLP and 2 SSR) exhibiting significant association with partial resistance. Coexistence of resistance homozygous alleles
(RR) at codominant SSR loci was correlated with high resistance. This study is the first attempt to develop PCR-based sequence
specific markers linked to partial rust resistance in coffee. 相似文献
7.
J. B. O. Owuor 《Euphytica》1985,34(2):355-360
Summary Melosis was studied in Coffea arabica, in induced tetraploid C. canephora, in their F1 hybrid (arabusta hybrid) and in backcross generations of the hybrid with C. arabica as recurrent parent. Irregularities were observed, consisting of univalents (especially in the arabusta hybrid), multivalents (especially in tetraploid C. canephora) and uneven distribution of chromosomes at first anaphase. Chromosome distribution was improved by backcrossing. Meiotic irregularities wer negatively correlated with pollen fertility. 相似文献
8.
The development of cultivars resistant to coffee leaf rust caused by the fungal pathogen Hemileia vastatrix is a priority in coffee breeding. However, only very few descendants of interspecific hybrids between Coffea arabica and diploid relative species have been used as resistance source. Identification of new sources of resistance appeared therefore particularly worthwhile. Hybrid plants derived from interspecific hybridization between C. arabica and Coffea canephora and found in neo‐natural coffee tree populations of New Caledonia were therefore investigated. Amplified Fragment Length Polymorphism and microsatellites amplification were used to evaluate the genetic diversity of 14 hybrid plants, and rust resistance was evaluated by inoculation with a panel of rust races representing a large variability in virulence. An important genetic diversity was characterized in hybrid plants originating from introgressions into C. arabica from various C. canephora progenitors. On the 14 plants tested for leaf rust resistance, eight appeared resistant to all races investigated. Such plant material should represent a highly valuable resource for C. arabica breeding against coffee leaf rust. 相似文献
9.
M. I. E. Arabi 《Euphytica》2005,145(1-2):161-170
Barley breeders in Syria attempting to develop barley (Hordeum vulgare L.) cultivars resistant to barley leaf stripe (BLS) disease caused by Pyrenophora graminea Ito & Kuribayashi [anamorph Drechslera graminea (Rabenh. Ex. Schlech. Shoem.)]. Information on the combining ability for BLS resistance in Syria is not available. This study
was conducted to evaluate, in 10 genetically diverse barley parents, general combining ability (GCA) and specific combining
ability (SCA) effects towards the determination of the genetic basis of disease resistance and to estimate genetic variability
for yield components and its modification by BLS. Ten parental genotypes varying in their reactions to BLS were crossed in
a half-diallel mating design to generate 45 full-sib families. The families and the parents were inoculated with P. graminea and evaluated for resistance in replicated field tests (three inoculated and three non-inoculated plots). The parents chosen
showed wide variations for resistance to BLS. Genetic component analysis showed significant effects for both GCA and SCA for
resistance to BLS, suggesting that additive as well as non-additive genetic mechanisms were involved in the expression of
resistance in these parents. GCA effects were more important than SCA effects. Resistant parents exhibited high negative GCA
indicating that additive gene effects were more predominant, and suggesting their prime suitability for use in barley breeding
programs to improve resistance to BLS. Narrow-sense heritability was 58% and broad-sense heritability was 99% indicating that
selection for BLS resistance should be effective in these crosses. A high genetic variability for the agronomic traits studied
was observed. Yield components decreased significantly in inoculated plants and more pronounced in diseased plants. Significant
GCA was observed for all traits. Values for GCA were, in some cases, significantly modified by BLS. This indicates that attention
must be paid to the danger of drawing conclusion in quantitative genetics studies dealing with both diseased and healthy plants.
Two genotypes, Banteng and Igri, had high negative GCA effects and are promising parents for enhancement of BLS resistance. 相似文献
10.
Summary Various aspects of pollen longevity, in vitro germination of pollen and controlled pollination in Coffea arabica were investigated. High pollen viability could be maintained for more than two years, much longer than previously reported, by storing it under vacuum at 18°C. The most satisfactory method of in vitro germination of pollen was the hanging drop in a Van Tieghem cell, with a 10°, sucrose solution. For artificial cross-pollination it is necessary to carry out emasculation and bagging at the latest one day before anthesis. The stigmas of unpollinated flowers remained receptive for at least nine days.This paper is published with permission of the Director, Coffee Research Station, Ruiru, Kenya 相似文献
11.
Microsatellites or simple sequence repeats (SSR) were used to assess polymorphism among 16 Coffea arabica and four Coffea canephora accessions, and to identify DNA introgression fragments from C. canephora in four C. arabica lines. Thirty‐one primer pairs allowed for the identification of 92 polymorphic alleles distributed over 37 loci. The C. arabica accessions derived from the genetic bases ‘Typica’ and ‘Bourbon’ were grouped separately according to their genetic origin. Two genotypes derived from a spontaneous hybrid (C arabica×C. canephora) were classified with the C. canephora accessions from Central Africa. Coffea canephora from West Africa were separated from the other accessions studied. Four alleles related to introgression (i.e. present in C. canephora and introgressed lines, and absent in C. arabica) were identified. The SSR markers were used successfully for characterization of a particular cultivar (‘Veranero’) from Costa Rica, which is known for its late maturity. 相似文献
12.
Rebecca S. Zwart Hilde Muylle Johan Van Huylenbroeck Erik Van Bockstaele Isabel Roldán-Ruiz 《Euphytica》2008,162(3):449-456
The inheritance of Fusarium head blight (FHB) resistance was investigated in eight western European wheat lines using a half-diallel
of F1 crosses. The parents and F1 crosses were point-inoculated, with a highly aggressive isolate of Fusarium graminearum, in replicated field and glasshouse trials. Type II resistance was assessed by measuring the % FHB spread and % wilted tips.
There was a good correlation between the two disease parameters, % FHB spread area under the disease progress curve (AUDPC)
and % wilted tips AUDPC (r = 0.86, P < 0.01). Correlation coefficients between the field and glasshouse environments were r = 0.46 (P < 0.01) for % FHB spread AUDPC and r = 0.40 (P < 0.05) for % wilted tips AUDPC. Both general combining ability (GCA) and specific combining ability (SCA) effects influenced
the inheritance of FHB resistance, suggesting that in this set of parents both additive and non-additive (dominance or epistatic)
effects influence the inheritance of type II FHB resistance. Highly significant GCA-by-environment (P < 0.0001) and SCA-by-environment (P < 0.005) interactions were also observed. Specific combinations of western European wheat varieties were identified with
type II FHB resistance at a level equal to or more resistant than the winter wheat variety ‘Arina’. 相似文献
13.
Seven single conidia isolates of Colletotrichum kahawae varying in pathogenicity were used to inoculate hybrid progenies from 66 crosses ofCoffea arabica cv. Ruiru 11. The objective of this study was to investigate the effect of pathogen variation on resistance of the Ruiru
11 cultivar. The main effects of crosses and isolates were significant (p ≤0.05) while their interaction effects were non-significant. Partitioning variance components indicated that the proportion
of phenotypic variance for resistance that is due to genetic effects was low. It was concluded that variation for resistance
among hybrid progenies of the Ruiru 11 cultivar was probably due to differences in aggressiveness of the pathogen as reflected
by the significant main effects of crosses and isolates in combination with other environmental factors which influence disease
epidemics. The coffee berry disease pathogen is unlikely to have adapted to the cultivar because of the non-significant crosses
× isolates interaction effects.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
14.
Interspecific hybrids were produced from reciprocal crosses between Brassica napus (2n = 38, AACC) and B. oleracea var. alboglabra (2n = 18, CC) to introgress the zero-erucic acid alleles from B. napus into B. oleracea. The ovule culture embryo rescue technique was applied for production of F1 plants. The effects of silique age, as measured by days after pollination (DAP), and growth condition (temperature) on the
efficiency of this technique was investigated. The greatest numbers of hybrids per pollination were produced under 20°/15°C
(day/night) at 16 DAP for B. oleracea (♀) × B. napus crosses, while under 15°/10°C at 14 DAP for B. napus (♀) × B. oleracea crosses. Application of the ovule culture technique also increased the efficiency of BC1 (F1 × B. oleracea) hybrid production by 10-fold over in vivo seed set. The segregation of erucic acid alleles in the self-pollinated backcross
generation, i.e. in BC1S1 seeds, revealed that the gametes of the F1 and BC1 plants carrying a greater number of A-genome chromosomes were more viable. This resulted in a significantly greater number
of intermediate and a smaller number of high-erucic acid BC1S1 seeds. 相似文献
15.
Cytogenetic characterization by karyotyping and determination of DNA content by flow cytometry of seven cultivated varieties
of Chenopodium was performed. Chenopodium quinoa cultivar Barandales and C. berlandieri subsp. nuttalliae cultigens Huauzontle, Quelite and Chia roja showed 2n = 4x = 36, x = 9. Statistically insignificant genome size differences for studied varieties ranged from 2.96 pg/2C (1 Cx = 724 Mbp) in C. quinoa to 3.04 pg/2C (1 Cx = 743 Mbp) in Huauzontle. Karyotype analyses revealed the presence of nine groups of four metacentric chromosomes, including
two pairs of chromosomes with satellites. The first pair of satellites was located on the largest pair of chromosomes and
the second on a different pair of chromosomes in all accessions analyzed. Variation among varieties was evident in chromosome
size, genome length (GL) and the position of satellites. Chia roja exhibited greatest GL (58.82 μm) and biggest chromosomes
(2.04 μm). Huauzontle showed the smallest GL (45.02 μm) and shortest chromosomes (1.60 μm). Comparison of GL in studied taxa
was statistically significant and allowed to define three groups according to the use given to these plants. These data indicate
that they are small, very stable genomes in terms of DNA content, and they support the allotetraploid origin(s) of C. berlandieri subsp. nuttalliae and C. quinoa. 相似文献
16.
Dry bean (Phaseolus vulgaris L.) is an important grain legume for small-scale farmers in eastern Africa who nonetheless, grow beans with limited phosphorus
(P) fertilizer supply or none at all. Phosphorus rank second, after nitrogen (N), as the most limiting soil nutrient in bean
production in East African soils. This study was conducted to determine combining ability for five polygenic traits in the
red mottled, large seeded bean market class, under low and high soil P conditions and two locations. Three parents tolerant
to low soil P were hybridized with five well adapted, but non-low P tolerant lines in a diallel mating scheme. The resulting
28 F1 hybrids were evaluated in a randomized complete block design with three replications, under low and high soil P conditions
at two sites. There were highly significant (P ≤ 0.001) differences among the genotypes for all the traits under all the study conditions. The GCA mean squares were highly
significant (P ≤ 0.001) for these traits, indicating importance of additive effects for both study conditions and sites. The GCA × Environment
and SCA × Environment were significant for all the parameters and test conditions. CAL143 had positive GCA effects that were
significant; except for 100-seed weight under P stress; for all the traits and under all the study conditions. The negative
GCA effects for the none P tolerant parents indicate that they impacted positively in imparting earliness. 相似文献
17.
This study was conducted to estimate the genetic effects on biomass yield in the interspecific hybrids between Brassica napus and B. rapa, and to evaluate the relationship between parental genetic diversity and its effect on biomass yield of interspecific hybrids.
Six cultivars and lines of oilseed B. napus and 20 cultivars of oilseed B. rapa from different regions of the world were chosen to produce interspecific hybrids using NC design II. Obvious genetic differences
between B. rapa and B. napus were detected by RFLP. In addition, Chinese B. rapa and European B. rapa were shown genetically differences. Plant biomass yield from these interspecific hybrids were measured at the end of flowering
period. Significant differences
were detected among general combining ability (GCA) effects over two years and specific combining ability (SCA) effects differences
were detected in 2000. The ratios of mean squares, (σ2
GCA(f) + σ2
GCA(m)) / (σ2
GCA(f) + σ2
GCA(m) + σ2
SCA), were 89% and 88% in 1999 and 2000, respectively. This indicates that both additive effects and non-additive effects contributed
to the biomass yield of interspecific hybrids and the former played more important role. Some European B. rapa had significant negative GCA effects while many of Chinese B. rapa had significant positive GCA effects, indicating that Chinese B. rapa may be a valuable source for transferring favorable genes of biomass yield to B. napus. Significant positive correlation between parental genetic distance and biomass yield of interspecific hybrids implies that
larger genetic distance results in higher biomass yield for the interspecific hybrids. A way to utilize interspecific heterosis
for seed yield was discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
Sweetpotato virus disease (SPVD) is due to the dual infection and synergistic interaction of Sweetpotato feathery mottle potyvirus (SPFMV) and Sweetpotato chlorotic stunt crinivirus(SPCSV), and causes up to 98% yield loss in sweetpotato in East Africa. This study was conducted to determine the inheritance
of resistance to SPVD in sweetpotato and to estimate the nature of genetic variance. Ten parental clones varying in reaction
to SPVD were crossed in a half diallel mating design to generate 45 full-sib families. The families were graft-inoculated
with SPCSV and SPFMV to induce SPVD and evaluated for resistance in a randomized complete block design at two sites in Namulonge,
Uganda during 1998–2000. In serological assays for SPFMV and SPCSV,resistance to symptom development and recovery from initial
systemic SPVD symptoms, characterised resistant genotypes. Genetic component analysis showed significant effects for both
general combining ability (GCA) and specific combining ability (SCA) for resistance to SPVD. GCA to SCA variance component
ratios were large (0.51–0.87), hence GCA effects were more important than SCA effects. Resistant parents exhibited high GCA
indicating that additive gene effects were predominant in the inheritance of resistance to SPVD and recovery. Narrow-sense
heritability (31–41%) and broad-sense heritability (73–98%) were moderate to high, indicating that rapid genetic gains for
SPVD resistance could be accomplished by mass selection breeding techniques. Two genotypes, New Kawogo and Sowola, had high
negative GCA effects and had several families in specific crosses,which exhibited rapid recovery from SPVD,and are promising
parents for enhancement of SPVD resistance and recovery.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
19.
Screening for resistance to powdery mildew of Solanum melongena and wild related species was made in the field under natural infection conditions. A total of 172 accessions originating
from several geographical parts of the world were tested. Single plant selection for resistance was carried out and open-pollination
was used. Most S. melongena accessions were susceptible or highly susceptible to the disease. By S0 to S3 selection, an increase in the overall powdery mildew resistance level of S. melongena population was obtained and four S. melongena lines possessing a high level of resistance were obtained. Among the wild Solanum species, S. laciniatum and S. nigrum showed to be non-host plants of L. taurica. S. quinquangolare showed no symptoms of powdery mildew, S. linnaeanum, S. aculeatissimum, S. aviculare, S. pseudocapsicum were highly resistant, S. spinosissimum was resistant, S. gilo, S. capsicoides were susceptible or highly susceptible, and plants of S. sisymbriifolium showed a widely variable disease reaction. Four S. melongena resistant lines were obtained: PAVEG 10187 S3, PAVEG 10196 S3, P.I. 230279 S3 and P.I. 419198 S3. These S. melongena lines together with the resistant wild species could be used for genetic studies, classical breeding programs and biotechnological
applications. 相似文献
20.
Summary Selfed and cross-pollinated progenies of Icatu coffee plants and derivatives of Híbrido de Timor, with susceptibility or moderate resistance to coffee rust in the field, were tested with Hemileia vastatrix race II and isolate 2 (Is. 2) in the greenhouse or laboratory. Progenies from plants with a susceptible reaction type in the field (scores 8 and 9) all showed homogeneous levels of susceptibility similar to that of the control cultivars Mundo Novo and Catuaí of Coffea arabica. Variation for incomplete resistance was mainly expressed by low or heterogeneous reaction types and also by longer latency periods. Incomplete resistance to race II of some Icatu and Catimor plants, which is overcome by Is. 2, appeared to depend on a partially dominant gene. The expression of this gene may vary also according to the genetic background and some residual resistance to Is. 2 was observed. A few derivatives of Híbrido de Timor were more resistant to Is. 2 than to race II, suggesting the presence of a resistant factor to Is. 2 in this germplasm. Segregation in progenies from other plants with incomplete resistance to race II suggested presence of one or a few genes only, which in homozygous condition or in combination seem to confer near-complete or complete resistance. The results suggest that selection for incomplete resistance, expressed by intermediate reaction types, in Icatu and derivatives of Híbrido de Timor may not provide durable resistance to coffee rust. On the other hand, due to apparent additive gene action, phenotypic selection of plants with a highly resistant reaction type could facilitate the accumulation of several resistance alleles in one genotype, which could provide an efficient barrier against new race formation of the pathogen. 相似文献