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1.
Silvana Grandillo Hsin-Mei Ku Steven D. Tanksley 《Molecular breeding : new strategies in plant improvement》1996,2(3):251-260
In two previous quantitative trait locus (QTL) mapping studies conducted inLycopersicon esculentum x L. pimpinellifolium BC1 and BC2 populations we had localized a major QTL for fruit shape,fs8.1, to a ca. 20 cM interval on the short arm of chromosome 8, flanked by markers TG176 and CT92. At this QTL the allele from the wild species reduces the length of fruit, giving round-shaped fruit. In order to define more precisely the location offs8.1, near-isogenic lines (NILs) segregating for the region of interest were developed. The results from substitution mapping show that no recombination occurred betweenfs8.1 and the marker CD40 in 322 meioses. The gene action forfs8.1 was determined in a BC4F3 population to be partial dominance. The main effect offs8.1 is exerted on fruit length while fruit diameter is not significantly affected. A highly significant correlation (r=0.89;P<0.01) was found between fruit shape and ovary shape indicating that thefs8.1 gene product acts early in ovary development (preanthesis). Implications for the evolution of fruit shape and the feasibility of map-based cloning of this QTL are discussed. 相似文献
2.
Identifying the loci responsible for natural variation in fruit size and shape in tomato 总被引:18,自引:0,他引:18
S. Grandillo H. M. Ku S. D. Tanksley 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,99(6):978-987
Fruit size and shape are two major factors determining yield, quality and consumer acceptability for many crops. Like most
traits important to agriculture, both are quantitatively inherited. Despite their economic importance none of the genes controlling
either of these traits have been cloned, and little is known about the control of the size and shape of domesticated fruit.
Tomato represents a model fruit-bearing domesticated species characterized by a wide morphological diversity of fruits. The
many genetic and genomic tools available for this crop can be used to unraveal the molecular bases of the developmental stages
which presumably influence fruit architecture, size and shape. The goal of this review is to summarize data from the tomato
QTL studies conducted over the past 15 years, which together allow the identification of the major QTLs responsible for fruit
domestication in tomato. These results provide the starting point for the isolation of the genes involved in fruit-size/shape
determination in tomato and potentially other fruit-bearing plants.
Received: 21 January 1999 / Accepted: 12 March 1999 相似文献
3.
F. Taguchi-Shiobara S. Y. Lin K. Tanno T. Komatsuda M. Yano T. Sasaki S. Oka 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(5-6):828-833
Quantitative trait loci (QTL) controlling the regeneration ability of rice seed callus were detected using 245 RFLP markers
and 98 BC1F5 lines derived from two varieties, ‘Nipponbare’ and ‘Kasalath’. Regeneration ability was evaluated by two indices: average
number of regenerated shoots per callus (NRS) and regeneration rate (RR). The BC1F5 lines showed continuous segregation for both indices. Five putative QTL for NRS (tentatively named qRg1, qRg2, qRg4a, qRg4b and qRg4c) located on chromosomes 1, 2 and 4 were detected. Digenic interaction among these detected QTL was not significant (P<0.01). Among the five QTL detected, four ‘Kasalath’ alleles and one ‘Nipponbare’ allele increased NRS. According to an estimate
based on the nearest marker loci, the five QTL accounted for 38.5% of the total phenotypic variation of the BC1F5 lines. For RR, four putative QTL were detected on chromosomes 2 and 4, and all of these were in the same chromosomal regions
as the NRS QTL. The four RR QTL accounted for 32.6% of the total phenotypic variation.
Received: 7 November 1996 / Accepted: 25 April 1997 相似文献
4.
S. Doganlar A. Frary S. D. Tanksley 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,100(8):1267-1273
The seeds of domesticated plants are normally much larger than those of their wild counterparts. This change in seed weight
was most likely in response to the selection pressure for yield, uniform germination and seedling vigor which was exerted
by humans during domestication. However, despite the evolutionary and agronomic significance of seed weight, very little is
know about the genetic and developmental controls of this trait; and, thus far, none of the genes in this pathway have been
isolated from any plant species. QTL mapping experiments conducted in tomato during the past decade have allowed the identification
of many seed-weight QTLs and have also revealed that only a few loci are responsible for the majority of the seed-weight changes
that accompanied the domestication of tomato. This review presents a consensus map for seed weight QTL identified in previously
published reports and in unpublished results from our laboratory. This summary of seed-weight QTL data allows for the identification
of the major loci controlling this trait in the genus Lycopersicon. It is hoped that this work will allow the elucidation of this important phenotypic transition that occurred during crop-plant
domestication and will also provide the starting point for the cloning of a gene responsible for seed-weight variation.
Received: 21 April 1999 / Accepted: 13 October 1999 相似文献
5.
The genetic basis of pear-shaped tomato fruit 总被引:1,自引:0,他引:1
H.-M. Ku S. Doganlar K.-Y. Chen S. D. Tanksley 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,99(5):844-850
Molecular-marker analysis of a cross between yellow pear, a tomato variety bearing small, pear-shaped fruit, and the round-fruited,
wild species, Lycopersicon pimpinellifolium LA1589, revealed that pear-shaped fruit is determined largely by a major QTL on chromosome 2 and, to a lesser extent, a minor
QTL on chromosome 10. The locus on chromosome 2 was also detected in a cross between yellow pear and the round-fruited introgression
line (IL2–5) which carried the distal portion of chromosome 2 from the Lycopersicon pennellii genome. Based on its map position, we propose that the locus detected on chromosome 2 is the same as a locus referred to
as ovate in the early tomato literature (Linstrom 1926, 1927). The fruit-shape index (length/diameter) and neck constriction were
highly correlated in both populations suggesting that ovate exerts control over both traits or that the genes for these traits are tightly linked on chromosome 2. Using two-way ANOVA
test, the minor QTL on chromosome 10 showed no significant interaction with the ovate locus on chromosome 2 with respect to the fruit-shape index. For ovate round fruit was dominant to elongated fruit in the L. pimpinellifolium populations, but additive in the IL2–5 population. Thus far, no genes controlling fruit shape have been cloned. The molecular
mapping of the ovate locus may ultimately lead to its isolation via map-based cloning.
Received: 8 January 1999 / Accepted: 30 January 1999 相似文献
6.
C. P. Joshi N. Y. Klueva K. J. Morrow H. T. Nguyen 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(5-6):834-841
We have used a combination of molecular and classical genetic approaches to delineate the relationship between a specific
HSP member and cell viability under heat stress. Using recombinant inbred lines (RILs) of wheat, derived from a cross of the
thermotolerant cultivar ‘Mustang’ and the thermosusceptible cultivar ‘Sturdy,’ we have identified a unique HSP and a differentially
expressed cDNA sequence, both related to the plastid-localized HSP26 gene family, that are closely associated with acquired
thermotolerance in wheat. An isoform of HSP26 was synthesized under heat stress in all examined thermotolerant RILs and ‘Mustang’,
and was absent in all examined thermosusceptible RILs and ‘Sturdy.’ Using a modified differential-display method, we have
also identified a gene-specific cDNA sequence that is similar to other known members of the wheat HSP26 gene family and is
selectively expressed in ‘Mustang’ and most of the examined thermotolerant RILs, but not expressed in ‘Sturdy’ and all the
thermosusceptible RILs. These results suggest a genetic linkage between the acquired thermotolerance trait and the differential
expression of a unique member of the HSP26 gene family.
Received: 21 April 1997 / Accepted: 2 May 1997 相似文献
7.
Identification and characterization of a novel locus controlling early fruit development in tomato 总被引:1,自引:0,他引:1
E. van der Knaap S. D. Tanksley 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,103(2-3):353-358
Cultivated tomatoes (Lycopersicon esculen- tum) encompass a wide range of fruit size and shape variants. This variation provides the basis for dissecting the genetic and
molecular pathways of ovary and fruit development. One fruit shape variant is displayed by the cultivar Sun 1642 (TA491).
TA491 has an elongated fruit phenotype, while the wild relative L. pimpinellifolium LA1589 produces fruit that are nearly perfect spheres, a shape typical of wild tomatoes. Developmental studies indicated
that the differences in fruit shape between TA491 and LA1589 are determined by events occurring immediately after pollination
and extending to 14 days post-pollination. Quantitative trait mapping revealed a single major locus on chromosome 7 (named
sun) to be responsible for the differential development of TA491 and LA1589 fruit. Other fruit shape loci characterized in tomato
(e.g. fs8.1 and ovate) exert their effects before anthesis and early in ovary development. sun is the first major locus identified in tomato controlling fruit shape through post-pollination events.
Received: 17 November 2000 / Accepted: 24 November 2000 相似文献
8.
High-resolution linkage analysis and physical characterization of the EIX-responding locus in tomato
M. Ron R. Kantety G. B. Martin N. Avidan Y. Eshed D. Zamir A. Avni 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,100(2):184-189
An ethylene-inducing xylanase (EIX) from Tricohoderma viride is a potent elicitor of ethylene biosynthesis, localized cell death and other defense responses in specific cultivars of
tobacco (Nicotiana
tabacum) and tomato (Lycopersicon esculentum). Wild species of tomato, such as Lycopersicon cheesmanii and Lycopersicon pennellii, do not respond to EIX treatment. The F1 progeny of a L. esculentum×L. cheesmanii and a L. esculentum×L. pennellii cross responded to EIX treatment with an increase in ethylene biosynthesis and the induction of localized cell death. The
F2 progeny of the above mentioned crosses segregated 3:1 (responding:non-responding). We mapped the EIX-responding locus (Eix) to the short arm of chromosome 7 using a population of introgression lines (ILs), containing small RFLP-defined chromosome
segments of L. pennellii introgressed into L. esculentum. RFLP analysis of 990 F2 plants that segregated for the introgressed segment mapped the Eix locus 0.1 cM and 0.9 cM from the flanking markers TG61 and TG131, respectively. Using the marker TG61 we isolated a yeast
artificial chromosome (YAC) clone that carries 300-kb DNA segments derived from the Eix region. By mapping the ends of this YAC clone we show that it spans the Eix locus. Thus, positional cloning of the Eix locus appears feasible.
Received: 20 March 1999 / Accepted: 30 April 1999 相似文献
9.
Suppressed recombination around the MXC3 locus, a major gene for resistance to poplar leaf rust 总被引:8,自引:0,他引:8
B. Stirling G. Newcombe J. Vrebalov I. Bosdet H.D. Bradshaw Jr. 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,103(8):1129-1137
A positional cloning strategy is being implemented in Populus for the isolation of the dominant MXC3 allele, which confers resistance to poplar leaf rust caused by Melampsora×columbiana (pathotype 3). AFLP markers were used to saturate the chromosomal region around the MXC3 locus in a large (n=1,902) Populus trichocarpa×P. deltoides (T×D) mapping pedigree segregating 1:1 for rust resistance and susceptibility. The high-resolution linkage map developed
around the MXC3 locus contains 19 AFLP markers and spans a genetic distance of 2.73 cM. Of the 19 AFLP markers, seven were found to co-segregate
with the locus. One co-segregating AFLP marker, CCG.GCT_01, was converted to an STS marker (BVS1) and used to identify a physical contig of overlapping BAC clones from the MXC3 region. Genetic and physical mapping of markers isolated from the BAC contig failed to delimit the MXC3 locus within a 300-kb interval defined by the overlapping BAC clones. This result indicates a >25-fold reduction in recombination
frequency in the MXC3 region compared to the average rate of recombination for the Populus genome.
Received: 8 December 2000 / Accepted: 1 March 2001 相似文献
10.
H. S. Suh Y. I. Sato H. Morishima 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(3-4):316-321
Weedy rice (Oryza sativa L.) is an important resource for breeding and for studying the evolution of rice. The present study was carried out to identify
the genetic basis of the weedy rices distributed in various countries of the world. One hundred and fifty two strains of weedy
rice collected from Bangladesh, Brazil, Bhutan, China, India, Japan, Korea, Nepal, Thailand and the USA were tested for variations
in six morpho-physiological characteristics and in 14 isozyme loci. Twenty six weedy strains selected from the above materials
were assayed for the Est-10 locus, six RAPD loci of the nuclear genome, and one chloroplast locus. From the results of multivariate analysis based on
the morpho-physiological characteristics and the isozymes, weedy rice strains were classified into indica and japonica types, and each type was further divided into forms resembling cultivated and wild rice. Thus, four groups designated as
I, II, III and IV were identified. Weedy strains of group I (indica-type similar to cultivars) were distributed mostly in temperate countries, group II (indica-type similar to wild rice) in tropical countries, group III (japonica-type similar to cultivars) in Bhutan and Korea, group IV ( japonica-type similar to wild rice) in China and Korea. In group I, classified as indica, several strains showed japonica-specific RAPD markers, while some others had japonica cytoplasm with indica-specific RAPD markers in a heterozygous state at several loci. One weedy strain belonging to group II showed a wild rice-specific
allele at the Est-10 locus. However, in groups III and IV, no variation was ound either for the markers on Est-10 or for the RAPD loci tested. Judging from this study, weedy rice of group I might have originated at least partly from gene
flow between indica and japonica, whereas that of group II most probably originated from gene flow between wild and cultivated indica rice. Weedy rice of group III is thought to have originated from old rice cultivars which had reverted to a weedy form, and
that of group IV from gene flow between japonica cultivars and wild rice having japonica backgrounds.
Received: 2 May 1996 / Accepted: 30 August 1996 相似文献
11.
Tör M Manning K King GJ Thompson AJ Jones GH Seymour GB Armstrong SJ 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2002,104(2-3):165-170
Cnr (Colourless non-ripening) is a dominant pleiotropic ripening mutation of tomato (Lycopersicon esculentum) which has previously been mapped to the proximal region of tomato chromosome 2. We describe the fine mapping of the Cnr locus using both linkage analysis and fluorescence in situ hybridisation (FISH). Restriction fragment length polymorphism
(RFLP)-, amplified restriction fragment polymorphism (AFLP)-, and cleaved amplified polymorphic sequence (CAPS)-based markers,
linked to the Cnr locus were mapped onto the long arm of chromosome 2. Detailed linkage analysis indicated that the Cnr locus was likely to lie further away from the top of the long arm than previously thought. This was confirmed by FISH, which
was applied to tomato pachytene chromosomes in order to gain an insight into the organisation of hetero- and euchromatin and
its relationship to the physical and genetic distances in the Cnr region. Three molecular markers linked to Cnr were unambiguously located by FISH to the long arm of chromosome 2 using individual BAC probes containing these single-copy
sequences. The physical order of the markers coincided with that established by genetic analysis. The two AFLP markers most-closely
linked to the Cnr locus were located in the euchromatic region 2.7-cM apart. The physical distance between these markers was measured on the
pachytene spreads and estimated to be approximately 900 kb, suggesting a bp:cM relationship in this region of chromosome 2
of about 330 kb/cM. This is less than half the average value of 750 kb/cM for the tomato genome. The relationship between
genetic and physical distances on chromosome 2 is discussed.
Received: 11 January 2001 / Accepted: 30 April 2001 相似文献
12.
Identification of a new major QTL associated with resistance to soybean cyst nematode (Heterodera glycines) 总被引:4,自引:0,他引:4
I. Schuster R. V. Abdelnoor S. R. R. Marin V. P. Carvalho R. A. S. Kiihl J. F. V. Silva C. S. Sediyama E. G. Barros M. A. Moreira 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,102(1):91-96
Resistance of soybean [Glycine max (L.) Merr.] to cyst nematode (SCN) (Heterodera glycines Ichinohe), one of the most destructive pathogens affecting soybean, involves a complex genetic system. The identification
of QTLs associated with SCN resistance may contribute to the understanding of such system. The objective of this work was
to identify and map QTLs for resistance to SCN Race 14 with the aid of molecular markers. BC3F2:3 and F2:3 populations, both derived from an original cross between resistant cv. Hartwig and the susceptible line BR-92–31983 were
screened for resistance to SCN Race 14. Four microsatellite (Satt082, Sat_001, Satt574 and Satt301) and four RAPD markers
(OPAA-11795, OPAE-08837, OPR-07548 and OPY-072030) were identified in the BC3F2:3 population using the bulked segregant analysis (BSA) technique. These markers were amplified in 183 F2:3 families and mapped to a locus that accounts for more than 40% of the resistance to SCN Race 14. Selection efficiency based
on these markers was similar to that obtained with the conventional method. In the case of the microsalellite markers, which
identify homozygous resistant genotypes, the efficiency was even higher. This new QTL has been mapped to the soybean linkage
group D2 and, in conjunction with other QTLs already identified for SCN resistance, will certainly contribute to our understanding
of the genetic basis of resistance of this important disease in soybean.
Received: 12 October 1999 / Accepted: 14 April 2000 相似文献
13.
Genetic and physical mapping of xa13, a recessive bacterial blight resistance gene in rice 总被引:6,自引:0,他引:6
A. C. Sanchez L. L. Ilag D. Yang D. S. Brar F. Ausubel G. S. Khush M. Yano T. Sasaki Z. Li N. Huang 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(6-7):1022-1028
The recessive gene, xa13, confers resistance to Philippine race 6 (PXO99) of the bacterial blight pathogen Xanthomonas oryzae pv oryzae. Fine genetic mapping and physical mapping were conducted as initial steps in an effort to isolate the gene. Using nine selected
DNA markers and two F2 populations of 132 and 230 plants, xa13 was fine-mapped to a genomic region <4 cM on the long arm of rice chromosome 8, flanked by two RFLP markers, RG136 and R2027.
Four DNA markers, RG136, R2027, S14003, and G1149, in the target region were used to identify bacterial artificial chromosome
(BAC) clones potentially harboring the xa13 locus from a rice BAC library. A total of 11 BACs were identified, forming four separate contigs including a single-clone
contig, 29I3, associated with the RG136 STS marker, the S14003 contig consisting of four clones (44F8, 41O2, 12A16, and 12F20),
the G1149 contig with two clones, 23D11 and 21H18, and the R2027 contig consisting of four overlapping clones, 42C23, 30B5,
6B7 and 21H14. Genetic mapping indicated that the xa13 locus was contained in the R2027 contig. Chromosomal walking on the R2027 contig resulted in two more clones, 33C7 and 14L3.
DNA fingerprinting showed that the six clones of the R2027 contig were overlapping. Clone 44F8 hybridized with a single fragment
from the clone 14L3, integrating the R2027 and S14003 contigs into a single contig consisting of ten BAC clones with a total
size of approximately 330 kb. The physical presence of the xa13 locus in the contig was determined by mapping the ends of the BAC inserts generated by TAIL-PCR. In an F2 population of 230 plants, the BAC-end markers 42C23R and 6B7F flanked the xa13 locus. The probes 21H14F and 21H14R derived from BAC clone 21H14 were found to flank xa13 at a distance of 0.5 cM on either side, using a second F2 population of 132 plants. Thus, genetic mapping indicated that the contig and the 96-kb clone, 21H14, contained the xa13 locus.
Received: 15 August 1998 / Accepted: 29 September 1998 相似文献
14.
I. Levin N. Gilboa E. Yeselson S. Shen A. A. Schaffer 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,100(2):256-262
A genetic trait determining the ratio of fructose to glucose in mature tomato fruits is described. A backcross breeding program
based on the interspecific cross of Lycopersicon
hirsutum and L. esculentum yielded stable genotypes with a high ratio of fructose to glucose (>1.5:1) compared with the approximately equimolar ratios
found in L. esculentum. Two inter-simple- sequence repeat (ISSR) DNA sequences, highly associated (20 <LOD score <21) with the trait, were identified.
The markers were found to be less associated with either glucose or fructose levels individually (2 <LOD score <3) and were
statistically unlinked to total sugars and total soluble solids (TSS). These two ISSR bands segregated in a dominant fashion
and were found to be allelic to each other, one associated in coupling and the other in repulsion with the trait of high fructose
to glucose ratio. Both ISSR markers were mapped to the centromeric region of tomato chromosome 4. Quantitative analysis of
the identified locus, based on data from segregating F2, BC and F3 populations from the cross between genotypes having high and low fructose to glucose ratios, suggested that the L. hirsutum-derived allele (Fgr
H), which increases the fructose to glucose ratio, is partially dominant. Fgr
H leads to an increase in fructose levels and a subsequent decrease in glucose levels, with no effect on total hexose levels.
Accordingly, we conclude that the Fgr locus modulates the partitioning of hexose sugars between fructose and glucose, with no effect on total sugars or TSS.
Received: 8 March 1999 / Accepted: 12 May 1999 相似文献
15.
16.
S. L. Blauth G. A. Churchill M. A. Mutschler 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(3-4):458-467
Lycopersicon pennellii LA716, a wild relative of tomato, is resistant to a number of insect pests due to the accumulation of acylsugars exuded from
type IV trichomes. These acylsugars are a class of compounds including both acylglucoses and acylsucroses. Intraspecific populations
between L. pennellii LA716 and L. pennellii LA1912, the latter an accession that assorts for low-level acylsugar accumulation, were created to study the inheritance
of type IV trichome density, acylsugar accumulation levels, percentage of acylsugars that are acylglucoses, and leaf area.
The F2 population was subsequently used to determine genomic regions associated with these traits. The relative proportion of acylglucoses
and acylsucroses was found to be largely controlled by a single locus near TG549 on chromosome 3. One locus on chromosome
10 showed significant associations with acylsugar levels. In addition, 1 locus on chromosome 4 showed significant associations
with leaf area. Ten additional loci showed modest associations with one or more of the traits examined, 5 of which have been
previously reported.
Received: 13 March 1997 / Accepted: 19 September 1997 相似文献
17.
Toward positional cloning of Vgt1, a QTL controlling the transition from the vegetative to the reproductive phase in maize 总被引:1,自引:0,他引:1
Salvi S Tuberosa R Chiapparino E Maccaferri M Veillet S van Beuningen L Isaac P Edwards K Phillips RL 《Plant molecular biology》2002,48(5-6):601-613
Vgt1 (Vegetative to generative transition 1) is a quantitative trait locus (QTL) for flowering time in maize (Zea mays L.). Vgt1 was initially mapped in a ca. 5-cM interval on chromosome bin 8.05, using a set of near-isogenic lines (NILs) in the genetic background of the late dent line N28, with the earliness allele introgressed from the early variety Gaspé Flint. A new large mapping population was produced by crossing N28 and one early NIL with a ca. 6-cM long Gaspé Flint introgression at the Vgt1 region. Using PCR-based assays at markers flanking Vgt1, 69 segmental NILs homozygous for independent crossovers near the QTL were developed. When the NILs were tested in replicated field trials for days to pollen shed (DPS) and plant node number (ND), the QTL followed a Mendelian segregation. Using bulk segregant analysis and AFLP profiling, 17 AFLP markers linked to the QTL region were identified. Statistical analysis indicated a substantial coincidence of the effects of Vgt1 on both DPS and ND. Vgt1 was mapped at ca. 0.3 cM from an AFLP marker. As compared to DPS, the higher heritability of ND allowed for a more accurate assessment of the effects of Vgt1. The feasibility of the positional cloning of Vgt1 is discussed. 相似文献
18.
N. Chantret P. Sourdille M. Röder M. Tavaud M. Bernard G. Doussinault 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,100(8):1217-1224
Powdery mildew (Blumeria graminis f. sp. tritici) is one of the most damaging diseases of wheat (Triticum aestivum). The objective of this study was to locate and map a recently identified powdery mildew resistance gene, MlRE, carried by the resistant line RE714 using microsatellites uniformly distributed among the whole genome together with a bulked
segregant analysis (BSA). The bulks consisted of individuals with an extreme phenotype taken from a population of 140 F3 families issued from the cross between RE714 (resistant) and Hardi (susceptible). The population had been tested with three
powdery mildew isolates at the seedling stage. Qualitative interpretation of the resistance tests located the MlRE gene on the distal part of the long arm of chromosome 6A. A subsequent quantitative interpretation of the resistance permitted
us to detect another resistance factor on a linkage group assigned to chromosome 5D, which was constructed with microsatellites
for which a polymorphism of intensity between bulks was observed. This quantitative trait locus (QTL) explained 16.8– 25.34%
of the total variation. An interaction between both the resistant factor (MlRE and the QTL) was found for only one of the isolates tested. This study shows the advantage of making a quantitative interpretation
of resistant tests and that the use of microsatellites combined with BSA is a powerful strategy to locate resistance genes
in wheat.
Received: 30 August 1999 / Accepted: 11 November 1999 相似文献
19.
Peronella japonica, a sand dollar, forms an abbreviated pluteus larva and metamorphoses within 3 days without feeding. In the present study,
the cleavage pattern of Peronella embryos was found to be quite irregular in the vegetal blastomeres at the fourth cleavage. Less than half of the embryos examined
formed four typical micromeres. The majority formed zero, one, two or three typical micromeres of regular size, and the blastomere(s)
remaining in the vegetal-most region was atypical in size and/or its direction of division. Most embryos were able to form
pluteus larvae and a considerable proportion of these metamorphosed into juvenile sea urchins, regardless of whether or not
they had formed four typical micromeres of regular size, although embryos which formed no typical micromeres developed into
pluteus larvae less frequently. The micromere progeny in Peronella embryos form skeletogenic mesenchyme cells. The average numbers of skeletogenic mesenchyme cells in the three sand dollar
species, Clypeaster japonicus, Astriclypeus manni and P. japonica were 62, 122 and 219, respectively. In these species, the skeletogenic mesenchyme cell-specific glycoprotein (msp130) was
first detected immediately after ingression of the primary mesenchyme cells, spicules appeared at the early gastrula stage
and triradiate spicules were found in late gastrulae. Appearance of these characteristics was markedly accelerated in the
embryos of A. manni and P. japonica in comparison with those of C. japonicus. Each step in the formation of larval spicules was equally accelerated in A. manni and P. japonica, although the appearance of the adult skeleton was further accelerated in P. japonica in comparison with A. manni, possibly because of omission of the four- to eight-armed pluteus stages.
Received: 1 September 1995 / Accepted in revised form: 21 May 1995 相似文献
20.
Detection and analysis of QTLs for resistance to the brown planthopper, Nilaparvata lugens, in a doubled-haploid rice population 总被引:5,自引:0,他引:5
S. N. Alam M. B. Cohen 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(8):1370-1379
We used a mapping population of 131 doubled-haploid lines, produced from a cross between an improved indica rice variety (IR64) and a traditional japonica variety (Azucena), to detect quantitative trait loci (QTLs) for resistance to the brown planthopper (BPH), Nilaparvata lugens. We evaluated the parents and mapping population with six tests that measure varying combinations of the three basic mechanisms
of insect host plant resistance, i.e., antixenosis, antibiosis, and tolerance. To factor-out the effect of the major resistance
gene Bph1 from IR64, the screening was done with two BPH populations from Luzon Island, The Philippines, that are almost completely
adapted to this gene. A total of seven QTLs associated with resistance were identified, located on 6 of the 12 rice chromosomes.
Individual QTLs accounted for between 5.1 and 16.6% of the phenotypic variance. Two QTLs were predominantly associated with
a single resistance mechanism: one with antixenosis and one with tolerance. Most of the QTLs were derived from IR64, which
has been shown to have a relatively durable level of moderate resistance under field conditions. The results of this study
should be useful in transferring this resistance to additional rice varieties.
Received: 10 May 1998 / Accepted: 4 June 1998 相似文献