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1.
Progress in improving processing attributes in potato   总被引:3,自引:0,他引:3  
The recent publication of a molecular-function map of carbohydrate metabolism and transport in potato enables a candidate-gene approach to be used to solve the problem of cold-sweetening, signifying a significant step in our understanding of this economically important trait. With confirmation of the role that many important enzymes play in starch metabolism and their position on a detailed linkage map, we should now be able to make progress in manipulating this trait, either through conventional means such as marker-assisted selection or through transgenic approaches.  相似文献   

2.
A candidate gene approach has been used as a first step to identify the molecular basis of quantitative trait variation in potato. Sugar content of tubers upon cold storage was the model trait chosen because the metabolic pathways involved in starch and sugar metabolism are well known and many of the genes have been cloned. Tubers of two F(1) populations of diploid potato grown in six environments were evaluated for sugar content after cold storage. The populations were genotyped with RFLP, AFLP, and candidate gene markers. QTL analysis revealed that QTL for glucose, fructose, and sucrose content were located on all potato chromosomes. Most QTL for glucose content mapped to the same positions as QTL for fructose content. QTL explaining >10% of the variability for reducing sugars were located on linkage groups I, III, VII, VIII, IX, and XI. QTL consistent across populations and/or environments were identified. QTL were linked to genes encoding invertase, sucrose synthase 3, sucrose phosphate synthase, ADP-glucose pyrophosphorylase, sucrose transporter 1, and a putative sucrose sensor. The results suggest that allelic variants of enzymes operating in carbohydrate metabolic pathways contribute to the genetic variation in cold sweetening.  相似文献   

3.
In the absence of a complete and annotated bovine genome sequence, detailed human-bovine comparative maps are one of the most effective tools for identification of positional candidate genes contributing to quantitative trait loci (QTL) in cattle. In the present study, eight genes from human chromosome 8 were selected for mapping in cattle to improve breakpoint resolution and confirm gene order on the comparative map near the 40 cM region of the BTA27 linkage map where a QTL affecting dairy form had previously been identified. The resulting map identified ADRB3 as a positional candidate gene for the QTL contributing to the dairy form trait based on its estimated position between 40 and 45 cM on the linkage map. It is also a functional candidate gene due to its role in fat metabolism, and polymorphisms in the ADRB3 gene associated with obesity and metabolic disease in humans, as well as, carcass fat in sheep. Further studies are underway to investigate the existence of polymorphisms in the bovine ADRB3 gene and their association with traits related to fat deposition in cattle.  相似文献   

4.
Late blight caused by the oomycete Phytophthora infestans is the economically most important and destructive disease in potato cultivation. Quantitative resistance to late blight available in tetraploid cultivars is correlated with late maturity in temperate climates, which is an undesirable characteristic. A total of 30 DNA-based markers known to be linked to loci for pathogen resistance in diploid potato were selected and tested as polymerase chain reaction-based markers for linkage with quantitative trait loci (QTL) for late blight resistance and plant maturity in two half-sib families of tetraploid potatoes. Most markers originated from within or were physically closely linked to candidate genes for quantitative resistance factors. The families were repeatedly evaluated in the field for quantitative resistance to late blight and maturity. Resistance was corrected for the maturity effect. Nine of eleven different map segments tagged by the markers harbored QTL affecting maturity-corrected resistance. Interactions were found between unlinked resistance QTL, providing testable strategies for marker-assisted selection in tetraploid potato. Based on the linkage observed between QTL for resistance and plant maturity and based on the genetic interactions observed between candidate genes tagging resistance QTL, we discuss models for the molecular basis of quantitative resistance and maturity.  相似文献   

5.
Testing possible associations between physiological and biochemicaltraits by comparing plant phenotypes and looking for correlationsbetween them is unreliable. The development of molecular markertechnologies offers powerful alternative methods to examinethe relationships between traits. This review describes thegenetical methods required to analyse possible associationsbetween traits that are inherited in a quantitative manner usingquantitative trait locus (QTL) analysis. The regulation of carbohydratemetabolism is chosen as an example of how QTL analysis can beused to identify key control factors in a series of processes,by identifying possible candidate genes for QTL effects on sucroseand starch metabolism. Methods are also described to study theassociation between physiological traits such as abscislc acidconcentrations and stomata1 conductance. Advantages and somelimitations of QTL analysis over other methods currently inuse by physiologists to test associations between traits arediscussed. Key words: Candidate genes, genetic maps, molecular markers, quantitative trait locus (QTL) analysis, physiological traits  相似文献   

6.
Iron deficiency chlorosis (IDC) is a yield limiting problem in soybean (Glycine max (L.) Merr) production regions with calcareous soils. Genome-wide association study (GWAS) was performed using a high density SNP map to discover significant markers, QTL and candidate genes associated with IDC trait variation. A stepwise regression model included eight markers after considering LD between markers, and identified seven major effect QTL on seven chromosomes. Twelve candidate genes known to be associated with iron metabolism mapped near these QTL supporting the polygenic nature of IDC. A non-synonymous substitution with the highest significance in a major QTL region suggests soybean orthologs of FRE1 on Gm03 is a major gene responsible for trait variation. NAS3, a gene that encodes the enzyme nicotianamine synthase which synthesizes the iron chelator nicotianamine also maps to the same QTL region. Disease resistant genes also map to the major QTL, supporting the hypothesis that pathogens compete with the plant for Fe and increase iron deficiency. The markers and the allelic combinations identified here can be further used for marker assisted selection.  相似文献   

7.
Understanding genetic characteristics in rice populations will facilitate exploring evolutionary mechanisms and gene cloning. Numerous molecular markers have been utilized in linkage map construction and quantitative trait locus (QTL) mappings. However, segregation-distorted markers were rarely considered, which prevented understanding genetic characteristics in many populations. In this study, we designed a 384-marker GoldenGate SNP array to genotype 283 recombination inbred lines (RILs) derived from 93-11 and Nipponbare Oryza sativa crosses. Using 294 markers that were highly polymorphic between parents, a linkage map with a total genetic distance of 1,583.2 cM was constructed, including 231 segregation-distorted markers. This linkage map was consistent with maps generated by other methods in previous studies. In total, 85 significant quantitative trait loci (QTLs) with phenotypic variation explained (PVE) values≥5% were identified. Among them, 34 QTLs were overlapped with reported genes/QTLs relevant to corresponding traits, and 17 QTLs were overlapped with reported sterility-related genes/QTLs. Our study provides evidence that segregation-distorted markers can be used in linkage map construction and QTL mapping. Moreover, genetic information resulting from this study will help us to understand recombination events and segregation distortion. Furthermore, this study will facilitate gene cloning and understanding mechanism of inter-subspecies hybrid sterility and correlations with important agronomic traits in rice.  相似文献   

8.
We have used the linkage disequilibrium mapping method to test for an association between a candidate gene marker and resistance to Verticillium dahliae in tetraploid potato. A probe derived from the tomato Verticillium resistance gene (Ve1) identified homologous sequences (StVe1) in potato, which in a diploid population map to chromosome 9, in a position analogous to that of the tomato resistance gene. When a molecular marker closely linked (1.5 cM) to the homologues was used as a candidate gene marker on 137 tetraploid potato genotypes (mostly North American cultivars), the association between the marker and resistance was confirmed (P<0.001). The amount of phenotypic variation in resistance explained by the allele of the STM1051 marker was greater than 10% and 25% in two subpopulations that were inferred from coancestry data matrix. Cloning of homologues from the highly resistant potato cv. Reddale indicates that the resistance quantitative trait locus (QTL) comprises at least an eleven-member family, encoding plant-specific leucine-rich repeat proteins highly similar to the tomato Ve genes. The sequence analysis shows that all homologues are uninterrupted open reading frames and thus represent putative functional resistance genes. This is the first time that the linkage disequilibrium method has been used to find an association between a resistance gene and a candidate gene marker in tetraploid potato. We have shown that it is possible to map QTL directly on already available potato cultivars, without developing a new mapping population.Communicated by F. SalaminiAn erratum to this article can be found at  相似文献   

9.
New microsatellites markers [simple sequence repeat (SSR)] have been isolated from rose and integrated into an existing amplified fragment-length polymorphism genetic map. This new map was used to identify quantitative trait locus (QTL) controlling date of flowering and number of petals. From a rose bud expressed sequence tag (EST) database of 2,556 unigenes and a rose genomic library, 44 EST-SSRs and 20 genomic-SSR markers were developed, respectively. These new rose SSRs were used to expand genetic maps of the rose interspecific F1 progeny. In addition, SSRs from other Rosaceae genera were also tested in the mapping progeny. Genetic maps for the two parents of the progeny were constructed using pseudo-testcross mapping strategy. The maps consist of seven linkage groups of 105 markers covering 432 cM for the maternal map and 136 markers covering 438 cM for the paternal map. Homologous relationships among linkage groups between the maternal and paternal maps were established using SSR markers. Loci controlling flowering traits were localised on genetic maps as a major gene and QTL for the number of petals and a QTL for the blooming date. New SSR markers developed in this study will provide tools for the establishment of a consensus linkage map for roses that combine traits and markers in various rose genetic maps.  相似文献   

10.
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