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1.
Salt tolerance in Lycopersicon species. III. Detection of quantitative trait loci by means of molecular markers 总被引:1,自引:0,他引:1
M. P. Bretó M. J. Aśins E. A. Carbonell 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1994,88(3-4):395-401
A segregating population derived from a cross between L. esculentum cv Madrigal and a line of L. pimpinellifolium was used to identify genetic markers linked to QTLs involved in salinity tolerance in terms of yield, under a conductivity of 15 dS/m (171.1 mM NaCl). Six markers resulted, associated with QTLs affecting average fruit weight, fruit number and total weight under salinity. One of them, Aco-1, behaves reversely to the expectation from parental means; this and other features make it a promising target to obtain salt-tolerant tomatoes. Epistatic interactions were also found, thus affecting the criteria for marker-assisted selection. Although only 41% of the loci assayed were polymorphic, a high efficiency in identifying QTLs was achieved, since 43% of the marker loci are linked to QTLs for the trait under study. 相似文献
2.
Salt tolerance in Lycopersicon spp. VII. Pleiotropic action of genes controlling earliness on fruit yield 总被引:1,自引:0,他引:1
A. J. Monforte M. J. Asíns E. A. Carbonell 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(3-4):593-601
The change from vegetative to reproductive development (earliness) in Lycopersicon chesmannii line L2 was delayed for 20 weeks when compared to other Lycopersicon species under greenhouse conditions. The interspecific hybrid of L. chesmannii L2 and L. esculentum E9, a cherry tomato cultivar, also showed this delay in reproductive development. The distribution of this character in the
F2-derived population showed a bimodal shape, plants could be scored easily as “early” or “late” in two nutrient conditions
(optimum and high salinity). A QTL with major effects on earliness was detected in salinity, which explained 35.6% of the
phenotypic variation. The effect of this QTL greatly diminished under control conditions, indicating differences in the genetic
control of earliness between treatments. ACC synthase or phytochrome B2 are the products of candidate genes for such a major
QTL. Other QTLs with minor effects, and epistatic interactions, are also involved in earliness under both conditions. A “late”
F2 subpopulation yielded twice as much as an “early” F2; conversely, “early” plants were taller than “late” plants, regardless of the treatment. QTL analysis, carried out in both
subpopulations, showed that yield differences may be explained by chesmannii alleles showing negative additive effects at some QTLs only in the “early” subpopulation. The effect of population subdivision
on QTL analysis was investigated by computer simulations to show sample-size or random effects; thus, important pleiotropic
or regulatory effects of genes controlling earliness on yield that affect QTL analysis, have been reveiled. Therefore alleles
controlling earliness in L. chesmannii have to be taken into account for a more efficient utilization of the genetic resources of this species.
Received: 30 June 1998 / Accepted: 31 August 1998 相似文献
3.
M. Byrne J. C. Murrell J. V. Owen E. R. Williams G. F. Moran 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(5-6):975-979
Regions of the genome influencing frost tolerance in an outbred family of Eucalyptus nitens have been identified. Two QTLs present on the same linkage group, but located 40 cM apart, were identified using single-factor
analysis of variance. The QTLs explained between 7.7 and 10.8% of the phenotypic variation for frost tolerance in this family.
Analysis of marker loci linked to the QTLs showed one of them to have a simple mode of action with the effect segregating
from the male parent in the family. For the other QTL multiple alleles were identified. This QTL showed segregation from the
female parent which gave a positive effect on frost tolerance; however, an allele segregating from the male parent was identified
which showed a negative interaction with the allele for increased frost tolerance.
Received: 10 May 1997 / Accepted: 2 June 1997 相似文献
4.
Epistat : a computer program for identifying and testing interactions between pairs of quantitative trait loci 总被引:11,自引:0,他引:11
K. Chase F. R. Adler K. G. Lark 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(6-7):724-730
We describe a computer program, Epistat, which combines statistical methods and color-graphic displays to facilitate the
analysis of interactions between pairs of quantitative trait loci (QTLs). Epistat organizes genetic-mapping data and quantitative-trait
values into graphic displays which illustrate the individual effects of single loci as well as the interactions between any
two loci. Keyboard commands allow the user to search the data set for individual QTLs and to test for interactions between
QTLs. For a given trait, the program displays the effects of the alleles at each of two loci on the quantitative-trait value,
as well as the effects of the interactions between these alleles. Loglikelihood ratios are used to compare the likelihood
of explaining the effects by null, additive, or epistatic models. Examples of interactions in soybean are presented for near-infrared
transmittance (NIT), seed number, and reproductive period. Epistat has been used to find numerous interactions between QTLs
in soybean in which trait variation at one locus is conditional upon a specific allele at another.
Received: 16 January 1996 / Accepted: 27 September 1996 相似文献
5.
A. J. Monforte S. D. Tanksley 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,100(3-4):471-479
The near-isogenic Line TA523, containing a 40-cM introgression at the bottom of chromosome 1 from Lycopersicon hirsutum acc. LA1777, affects several agronomically important traits. A set of recombinant lines (subNILs) derived from the original
NIL TA523 were developed in order to fine-map, by substitution mapping, the genetic factors included within the original introgression.
In the current experiment, TA523 showed redder, rounded, less pigmented shoulder, lower-weighted fruits and higher brix, whereas
higher yield and brix*yield was observed only in the hybrid TA253×TA209 suggesting heterosis for these traits. By substitution
mapping we mapped independent genetic loci affecting brix, yield and fruit shape, whereas fruit weight, shoulder pigmentation
and external color mapped to a position coincident with the brix locus. Analysis of the subNILs revealed that the gene action
of most of the QTLs was additive or nearly additive. The exception was for the yield QTL which was dominant (d/a=0.7), eliminating
the possibility that yield increase is due to true overdominance at a single gene locus. However, no negative yield effects
were detected in other regions of the introgressed segment, as would be predicted by a dominance complementation model. Therefore,
epistatic interactions among genetic factors along the introgressed segment are suggested as the cause of yield heterosis.
Results from this study, combined with previous experiments involving different tomato wild species, demonstrate that the
base of chromosome 1 of tomato contains multiple QTLs affecting various agronomic and fruit traits and that these effects
can not be attributed to the pleiotropic effects of a single locus.
Received: 21 April 1999 / Accepted: 17 June 1999 相似文献
6.
QTLs and epistasis for aluminum tolerance in rice (Oryza sativa L.) at different seedling stages 总被引:11,自引:0,他引:11
P. Wu C. Y. Liao B. Hu K. K. Yi W. Z. Jin J. J. Ni C. He 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,100(8):1295-1303
To investigate the genetic background for aluminum (Al) tolerance in rice, a recombinant inbred (RI) population, derived from
a cross between an Al-sensitive lowland indica rice variety IR1552 and an Al-tolerant upland japonica rice variety Azucena, was used in culture solution. A molecular linkage map, together with 104 amplified fragment length
polymorphism (AFLP) markers and 103 restriction fragment length polymorphism (RFLP) markers, was constructed to map quantitative
trait loci (QTLs) and epistatic loci for Al tolerance based on the segregation for relative root length (RRL) in the population.
RRL was measured after stress for 2 and 4 weeks at a concentration of 1mM of Al3+ and a control with a pH 4.0, respectively. Two QTLs were detected at both the 2nd and the 4th weeks on chromosomes 1 and
12 from unconditional mapping, while the QTL on chromosome 1 was only detected at the 2nd stress week from conditional mapping.
The effect of the QTL on chromosome 12 was increased with an increase of the stress period from 2 to 4 weeks. The QTL on chromosome
1 was expressed only at the earlier stress, but its contribution to tolerance was prolonged during growth. At least one different
QTL was detected at the different stress periods. Mean comparisons between marker genotypic classes indicated that the positive
alleles at the QTLs were from the Al-tolerant upland rice Azucena. An important heterozygous non-allelic interaction on Al
tolerance was found. The results indicated that tolerance in the younger seedlings was predominantly controlled by an additive
effect, while an epistatic effect was more important to the tolerance in older seedlings; additionally the detected QTLs may
be multiple allelic loci for Al tolerance and phosphorus-uptake efficiency, or for Al and Fe2+ tolerance.
Received: 29 July 1999 / Accepted: 13 October 1999 相似文献
7.
Quantitative trait loci for the stay green trait in sorghum (Sorghum bicolor L. Moench): consistency across genetic backgrounds and environments 总被引:3,自引:0,他引:3
P. K. Subudhi D. T. Rosenow H. T. Nguyen 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,101(5-6):733-741
Stay green in sorghum (Sorghum bicolor L. Moench) is characterized by the plant’s ability to tolerate post-flowering drought stress, thereby delaying the premature
leaf and plant death. It contributes to normal grain filling and reduces the incidence of stalk lodging and charcoal rot disease
during the late stages of grain development. Breeding for improving post-flowering drought tolerance in sorghum hybrids remains
an important objective of sorghum breeders. Since evaluation of the stay green response is difficult and unreliable under
field conditions, due to the timing and intensity of moisture stress and large environmental interaction, progress in improving
drought tolerance by conventional breeding methods has been slow. The objective of the present study was to determine the
consistency of quantitative trait loci (QTLs) controlling stay green in sorghum. We re-evaluated the Recombinant Inbred Line
(RIL)-mapping population from the cross B35 x Tx7000 in two locations over 2 years and compared it with earlier reports. Analysis
using the combined stay green-rating means of seven environments and the expanded molecular map reconfirmed all four stay
green QTLs (Stg1, Stg2, Stg3 and Stg4) that were identified earlier by Xu et al. (2000). Similarly, comparison of the stay green QTL locations with earlier reported
results indicated that all four stay green QTLs showed consistency across different genetic backgrounds. Examination of the
stay green QTL profiles of the best and poorest stay-green lines indicated that three stay green QTLs, Stg1, Stg2 and Stg3, appear to be important for the expression of this trait when the percent phenotypic variation, and the consistency in different
backgrounds and different environments, are considered. A significant epistatic interaction involving Stg2 and a region on linkage group C was also identified for the stay green and chlorophyll content. We concluded that Stg2 is the most important QTL controlling stay green, explaining the maximum amount of phenotypic variation. This report further
strengthens our view to target the Stg2 QTL region for gene discovery in order to improve the basic understanding of the stay green phenomenon, which might be helpful
in manipulating this trait not only in sorghum but also in other cereal crop species.
Received: 12 January 2000 / Accepted: 12 February 2000 相似文献
8.
Mapping of quantitative trait loci controlling adaptive traits in coastal Douglas-fir. I. Timing of vegetative bud flush 总被引:1,自引:0,他引:1
K. D. Jermstad D. L. Bassoni K. S. Jech N. C. Wheeler D. B. Neale 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,102(8):1142-1151
Thirty three unique quantitative trait loci (QTLs) affecting the timing of spring bud flush have been identified in an intraspecific
mapping population of coastal Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco var. menziesii]. Both terminal and lateral bud flush were measured over a 4-year period on clonal replicates at two test sites, allowing
for the repeated estimation of QTLs. QTLs were detected on 12 linkage groups and, in general, each explained a small proportion
of the total phenotypic variance and were additive in effect. Several QTLs influence the timing of bud flush over multiple
years, supporting earlier evidence that the timing of bud flush through developmental stages is under moderate to strong genetic
control by the same suite of genes through developmental stages. However, only a few QTLs controlling the timing of bud flush
were detected at both test sites, suggesting that geographic location plays a major role in the phenology of spring growth.
A small number of QTLs with year and site interactions were also estimated.
Received: 20 July 2000 / Accepted: 19 October 2000 相似文献
9.
Quantitative trait loci influencing drought tolerance in grain sorghum (Sorghum bicolor L. Moench) 总被引:7,自引:0,他引:7
H. Kebede P. K. Subudhi D. T. Rosenow H. T. Nguyen 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,103(2-3):266-276
Drought is a major constraint in sorghum production worldwide. Drought-stress in sorghum has been characterized at both pre-flowering
and post-flowering stages resulting in a drastic reduction in grain yield. In the case of post-flowering drought stress, lodging
further aggravates the problem resulting in total loss of crop yield in mechanized agriculture. The present study was conducted
to identify quantitative trait loci (QTLs) controlling post-flowering drought tolerance (stay green), pre-flowering drought
tolerance and lodging tolerance in sorghum using an F7 recombinant inbred line (RIL) population derived from the cross SC56×Tx7000. The RIL lines, along with parents, were evaluated
for the above traits in multiple environments. With the help of a restriction fragment length polymorphism (RFLP) map, which
spans 1,355 cM and consists of 144 loci, nine QTLs, located over seven linkage groups were detected for stay green in several
environments using the method of composite interval mapping. Comparison of the QTL locations with the published results indicated
that three QTLs located on linkage groups A, G and J were consistent. This is considered significant since the stay green
line SC56 used in our investigation is from a different source compared to B35 that was used in all the earlier investigations.
Comparative mapping has shown that two stay green QTLs identified in this study corresponded to stay green QTL regions in
maize. These genomic regions were also reported to be congruent with other drought-related agronomic and physiological traits
in maize and rice, suggesting that these syntenic regions might be hosting a cluster of genes with pleiotropic effects implicated
in several drought tolerance mechanisms in these grass species. In addition, three and four major QTLs responsible for lodging
tolerance and pre-flowering drought tolerance, respectively, were detected. This investigation clearly revealed the important
and consistent stay green QTLs in a different stay green source that can logically be targeted for positional cloning. The
identification of QTLs and markers for pre-flowering drought tolerance and lodging tolerance will help plant breeders in manipulating
and pyramiding those traits along with stay green to improve drought tolerance in sorghum.
Received: 2 June 2000 / Accepted: 15 November 2000 相似文献
10.
QTL analysis of an advanced backcross of Lycopersicon peruvianum to the cultivated tomato and comparisons with QTLs found in other wild species 总被引:12,自引:0,他引:12
T. M. Fulton T. Beck-Bunn D. Emmatty Y. Eshed J. Lopez V. Petiard J. Uhlig D. Zamir S. D. Tanksley 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(5-6):881-894
A BC3 population previously developed from a backcross of Lycopersicon peruvianum, a wild relative of tomato, into the cultivated variety L. esculentum was analyzed for QTLs. Approximately 200 BC4 families were scored for 35 traits in four locations worldwide. One hundred and sixty-six QTLs were detected for 29 of those
traits. For more than half of those 29 traits at least 1 QTL was detected for which the presence of the wild allele was associated
with an agronomically beneficial effect despite the inferior phenotype of the wild parent. Eight QTLs for fruit weight could
be followed through the BC2, BC3, and BC4, generations, supporting the authenticity of these QTLs. Comparisons were made between the QTLs found in this study and those
found in studies involving two other wild species; the results showed that while some of these QTLs can be presumed to be
allelic, most of the QTLs detected in this study are ones not previously discovered.
Received: 9 April 1997 / Accepted: 20 May 1997 相似文献
11.
Identification and mode of action of quantitative trait loci affecting seedling height and leaf area in Eucalyptus nitens 总被引:6,自引:0,他引:6
M. Byrne J. C. Murrell J. V. Owen P. Kriedemann E. R. Williams G. F. Moran 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(5):674-681
Regions of the genome influencing height and leaf area in seedlings of a three-generation outbred pedigree of Eucalyptus nitens have been identified. Three QTLs affecting height and two QTLs affecting leaf area were located using single-factor analysis
of variance. The three QTLs affecting height each explained between 10.3 and 14.7% of the phenotypic variance, while the two
QTLs for leaf area each explained between 9.8 and 11.6% of the phenotypic variation. Analysis of fully informative marker
loci linked to the QTLs enabled the mode of action of the QTLs to be investigated. For three loci the QTL effect segregated
from only one parent, while for two loci the QTL showed multiple alleles and the effect segregated from both parents in the
pedigree. The two QTLs affecting leaf area were located in the same regions as two of the QTLs affecting height. Analysis
of these regions with fully informative markers showed that both QTLs were linked to the same markers, but one had a similar
size of effects and a similar mode of action for both height and leaf area, whilst the other showed a different mode of action
for the two traits. These regions may contain two closely linked genes or may involve a single gene with a pleiotrophic effect
on both height and leaf area. The QTL with the greatest effect showed multiple alleles and an intra-locus interaction that
reduced the size of the effect. Assessment for two of the QTLs in a second related family did not show an effect associated
with the marker loci; however, this was consistent with the mode of action of these QTLs and the pattern of inheritance in
the second family.
Received: 1 August 1996 / Accepted: 25 October 1996 相似文献
12.
T. Toojinda E. Baird A. Booth L. Broers P. Hayes W. Powell W. Thomas H. Vivar G. Young 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(1):123-131
Genome-analysis tools are useful for dissecting complex phenotypes and manipulating determinants of these phenotypes in breeding
programs. Quantitative trait locus (QTL)-analysis tools were used to map QTLs conferring adult plant resistance to stripe
rust (caused by Puccinia striiformis f.sp. hordei) in barley. The resistance QTLs were introgressed into a genetic background unrelated to the mapping population with one
cycle of marker-assisted backcrossing. Doubled-haploid lines were derived from selected backcross lines, phenotyped for stripe-rust
resistance, and genotyped with an array of molecular markers. The resistance QTLs that were introgressed were significant
determinants of resistance in the new genetic background. Additional resistance QTLs were also detected. The susceptible parent
contributed resistance alleles at two of these new QTLs. We hypothesize that favorable alleles were fixed at these new QTLs
in the original mapping population. Genetic background may, therefore, have an important role in QTL-transfer experiments.
A breeding system is described that integrates single-copy and multiplex markers with confirmation of the target phenotype
in doubled-haploid lines phenotyped in field tests. This approach may be useful for simultaneously producing agronomically
useful germplasm and contributing to an understanding of quantitatively inherited traits.
Received: 6 May 1997 / Accepted: 1 September 1997 相似文献
13.
Groos C Gay G Perretant MR Gervais L Bernard M Dedryver F Charmet G 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2002,104(1):39-47
In many wheat (Triticum aestivum L.) growing areas, pre-harvest sprouting (PHS) may cause important damage, and in particular, it has deleterious effects on
bread-making quality. The relationship between PHS and grain color is well known and could be due either to the pleiotropic
effect of genes controlling red-testa pigmentation (R) or to linkage between these genes and other genes affecting PHS. In the present work, we have studied a population of 194
recombinant inbred lines from the cross between two cultivars, ’Renan’ and ’Récital’, in order to detect QTLs for both PHS
resistance and grain color. The variety ’Renan’ has red kernels and is resistant to PHS, while ’Récital’ has white grain and
is highly susceptible to PHS. A molecular-marker linkage map of this cross was constructed using SSRs, RFLPs and AFLPs. The
population was evaluated over 2 years at Clermont-Ferrand (France). PHS was evaluated on mature spikes under controlled conditions
and red-grain color was measured using a chromameter. Over the 2 years, we detected four QTLs for PHS, all of them being co-localized
with QTLs for grain color. Three of them were located on the long arm of chromosomes 3 A, 3B and 3D, close to the loci where
the genes R and taVp1 were previously mapped. For these three QTLs, the resistance to PHS is due to the allele of the variety ’Renan’. Another
co-located QTL for PHS and grain color was detected on the short arm of chromosome 5 A. The resistance for PHS for this QTL
is due to the allele of ’Récital’.
Received: 13 December 2000 / Accepted: 24 April 2001 相似文献
14.
C. Frova P. Krajewski N. di Fonzo M. Villa M. Sari-Gorla 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,99(1-2):280-288
Grain yield is a complex trait, strongly influenced by the environment: severe losses can be caused by drought, a stress common
in most maize-growing areas, including temperate climatic zones. Accordingly, drought tolerance is one of the main components
of yield stability, and its improvement is a major challenge to breeders. The aim of the present work was the identification,
in maize genotypes adapted to temperate areas, of genomic segments responsible for the expression of drought tolerance of
yield components: ear length, ear weight, kernel weight, kernel number and 50-kernel weight. A linkage analysis between the
expression of these traits and molecular markers was performed on a recombinant inbred population of 142 families, obtained
by repeated selfing of the F1 between lines B73 and H99. The population, genotyped at 173 loci (RFLPs, microsatellites and AFLPs), was evaluated in well-watered
and water-stressed conditions. A drought tolerance index was calculated as the ratio between the mean value of the trait in
the two environments. For the traits measured, a highly positive correlation was found over the two water regimes, and more
than 50% of the quantitative trait loci (QTLs) detected were the same in both; moreover, the direction of the allelic contribution
was always consistent, the allele increasing the trait value being mostly from line B73. Several QTLs were common to two or
more traits. For the tolerance index, however, most of the QTLs were specific for a single component and different from those
controlling the basic traits; in addition, a large proportion of the alleles increasing tolerance were provided by line H99.
The data suggest that drought tolerance for yield components is largely associated with genetic and physiological factors
independent from those determining the traits per se. The implications of these results for developing an efficient strategy of marker-assisted selection for drought tolerance
are discussed.
Received: 19 October 1998 / Accepted: 28 December 1998 相似文献
15.
K. D. Jermstad D. L. Bassoni N. C. Wheeler T. S. Anekonda S. N. Aitken W. T. Adams D. B. Neale 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,102(8):1152-1158
Quantitative trait loci (QTLs) affecting fall and spring cold-hardiness were identified in a three-generation outbred pedigree
of coastal Douglas-fir [Pseudotsuga meniziesii (Mirb.) Franco var. menziesii]. Eleven QTLs controlling fall cold-hardiness were detected on four linkage groups, and 15 QTLs controlling spring cold-hardiness
were detected on four linkage groups. Only one linkage group contained QTLs for both spring and fall cold-hardiness, and these
QTLs tended to map in close proximity to one another. Several QTLs were associated with hardiness in all three shoot tissues
assayed in the spring, supporting previous reports that there is synchronization of plant tissues during de-acclimatization.
For fall cold-hardiness, co-location of QTLs was not observed for the different tissues assayed, which is consistent with
previous reports of less synchronization of hardening in the fall. In several cases, QTLs for spring or fall cold-hardiness
mapped to the same location as QTLs controlling spring bud flush. QTL estimations, relative magnitudes of heritabilities,
and genetic correlations based on clonal data in this single full-sib family, supports conclusions about the genetic control
and relationships among cold-hardiness traits observed in population samples of Douglas-fir in previous studies.
Received: 20 July 2000 / Accepted: 19 October 2000 相似文献
16.
E. Schiantarelli A. De la Peña M. Candela 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,102(2-3):335-341
The Landsberg erecta× Columbia recombinant inbred lines (RILs) of Arabidopsis have been used in order to identify and localize chromosome regions involved in the genetic control of the in vitro regeneration
ability. Callus morphology (CM) and shoot regeneration (SR) traits have been considered for both leaf and root explants. The
MAPMAKER analysis of leaf culture data has revealed at least one chromosome region involved with CM and several with SR, the
29–30 region of chromosome 1 being common for the two traits. Root explants did not segregate for CM but several QTLs have
been detected for SR. The chromosome regions involved with leaf culture regeneration seem to be different from those of root
cultures, although the regeneration of abnormal shoots in leaf explants share two chromosome regions with the regeneration
of normal shoots in root cultures.
Received: 19 April 2000 / Accepted: 12 May 2000 相似文献
17.
J.-F. Rami P. Dufour G. Trouche G. Fliedel C. Mestres F. Davrieux P. Blanchard P. Hamon 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(4):605-616
Quantitative trait loci (QTLs) for grain quality, yield components and other traits were investigated in two Sorghum caudatum×guinea
recombinant inbred line (RIL) populations. A total of 16 traits were evaluated (plant height, panicle length, panicle compactness,
number of kernels/panicle, thousand-kernel weight, kernel weight/panicle, threshing percentage, dehulling yield, kernel flouriness,
kernel friability, kernel hardness, amylose content, protein content, lipid content, germination rate and molds during germination
and after harvest) and related to two 113- and 100-point base genetic maps using simple (SIM) and composite (CIM) interval
mapping. The number, effects and relative position of QTLs detected in both populations were generally in agreement with the
distributions, heritabilities and correlations among traits. Several chromosomal segments markedly affected multiple traits
and were suspected of harbouring major genes. The positions of these QTLs are discussed in relation to previously reported
studies on sorghum and other grasses. Many QTLs, depending on their relative effects and position, could be used as targets
for marker-assisted selection and provide an opportunity for accelerating breeding programmes.
Received: 14 February 1998 / Accepted: 4 March 1998 相似文献
18.
H. El Attari P. M. Hayes A. Rebai G. Barrault G. Dechamp-Guillaume A. Sarrafi 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(1):95-100
Genetic variability for partial resistance to bacterial leaf streak in barley, caused by Xanthomonas campestris pv. hordei, was investigated in 119 doubled-haploid lines (DH) developed by the Hordeum bulbosum method from the F1 progeny of the cross between two cultivars, ‘Morex’ (resistant) and ‘Steptoe’ (susceptible). Two experiments were undertaken
in a randomized complete block design with three replicates, in a controlled growth chamber. Twenty seeds per replicate were
planted in plastic containers (60×40×8 cm) containing moistened vermiculite. At the two-leaf stage seedlings were inoculated
with an Iranian strain of the pathogen. Genetic variability was observed among the 119 DH lines for partial resistance to
the disease. Some DH lines were significantly more resistant than ‘Morex’ (resistant parent) to bacterial leaf streak. Genetic
gain in percentage of resistant parent for 5% of the selected DH lines was significant (47.70% and 33.72% in the first and
the second experiment, respectively). A QTL analysis of bacterial leaf streak resistance showed that three QTLs were detected
on chromosomes 3 and 7. Multilocus allelic effects of the three QTLs account for almost 54% of the mean difference between
the parents and nearly 30% of the phenotypic variation of the trait in the mean experiment. The resistance locus on chromosome
3, near ABG377, apprears to be a major gene.
Received: 15 July 1997 / Accepted: 4 August 1997 相似文献
19.
E. Grosselindemann M. Robertson J. A. Wilmer P. M. Chandler 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(8):1186-1192
The electrophoretic patterns of dehydrins extracted from mature seeds of a range of pea (Pisum) species revealed extensive variation in dehydrin polypeptide mobility. Variation was also observed among lines of P. sativum. Crosses between lines with different dehydrin electrophoretic patterns produced F1 seeds with additive patterns, and segregation in the F2 generation was consistent with a 1 : 2 : 1 ratio, indicating allelic variation at each of two dehydrin loci (Dhn2, Dhn3). Genetic linkage was observed between Dhn2 and Dhn3, and the segregation ratios indicated preferential transmission of one allele at the Dhn3 locus. Dehydrin cDNA clones were characterised that encoded the allelic variants at Dhn2 and Dhn3. Their deduced amino-acid sequences were very similar to each other as well as to the product of the Dhn1 locus reported previously. Comparisons were made between the sequences of allelic variants at a single locus, and between
the products of different loci. Differences in the electrophoretic mobilities between allelic variants at Dhn2 and Dhn3 were associated with differences in polypeptide length resulting principally from tandem duplications of 21 (Dhn2) or 24 (Dhn3) amino-acid residues. These duplications accounted for much of the difference in length between dehydrins encoded by the
different loci. The conserved core of one of the duplicated regions varied in copy number, and small insertions/deletions
of amino acids near this core also contributed to length variation both between allelic forms and between loci. Dehydrins
possess characteristic highly conserved amino-acid sequence motifs, yet vary considerably in length. Mechanisms involving
sequence duplication appear to be responsible for generating the length differences observed between allelic variants as well
as between the products of different loci.
Received: 12 June 1997 / Accepted: 29 October 1997 相似文献
20.
G. Barcaccia A. Mazzucato E. Albertini J. Zethof A. Gerats M. Pezzotti M. Falcinelli 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(1-2):74-82
Gametophytic apomixis in Kentucky bluegrass (Poa pratensis L.) involves the parthenogenetic development of unreduced eggs from aposporic embryo sacs. Attempts to transfer the apomictic
trait beyond natural sexual barriers require further elucidation of its inheritance. Controlled crosses were made between
sexual clones and apomictic genotypes, and the parthenogenetic capacity of (poly)diploid hybrids was ascertained by the auxin
test. A bulked segregant analysis with RAPD and AFLP markers was then used to identify a genetic linkage group related to
the apomictic mode of reproduction. This approach enabled us to detect both an AFLP marker located 6.6 cM from the gene that
putatively controls parthenogenesis and a 15.4-cM genomic window surrounding the target locus. A map of the P. pratensis chromosome region carrying the gene of interest was constructed using additional RAPD and AFLP markers that co-segregated
with the parthenogenesis locus. Highly significant linkage between parthenogenesis and a number of AFLP markers that also
appeared to belong to a tight linkage block strengthens the hypothesis of monogenic inheritance of this trait. If a single
gene is assumed, apomictic polyploid types of P. pratensis would be simplex for a dominant allele that confers parthenogenesis, and this genetic model would be further supported by
the bimodal distribution of the degree of parthenogenesis exhibited in the (poly)diploid progenies from sexual x apomictic
matings. The molecular tagging of apomixis in P. pratensis is an essential step towards marker-assisted breeding and map-based cloning strategies aimed at investigating and manipulating
its mode of reproduction.
Received: 13 January 1998 / Accepted: 19 January 1998 相似文献