282 results about "Functional genes" patented technology

The invention discloses an application of a rape BnC05ERF378 gene in improving the waterlogging resistance of a plant. The nucleotide sequence of the rape BnC05ERF378 gene is as shown in SEQ ID NO. 1. According to the invention, a brand new stain-resistant gene BnC05ERF378 is cloned from rape for the first time, and is transferred into arabidopsis thaliana to construct a pure line plant and complete stain resistance identification. Experimental results show that the growth state of the transgenic BnC05ERF378 gene arabidopsis thaliana is remarkably superior to that of a wild type after waterlogging treatment, the transgenic BnC05ERF378 gene arabidopsis thaliana can normally bolt, the survival rate is increased from 12.5% to 37.5%, it is fully proved that the gene can enhance the survivability of the plant in a waterlogging environment by regulating the response mechanism of the plant to waterlogging stress, and the survival rate of the plant is increased from 12.5% to 37.5%. And a key guarantee is provided for stable growth of plants under high-humidity, waterflooding and other adverse conditions. According to the discovery and application of the waterlogging-resistant gene BnC05ERF378 disclosed by the invention, a clear functional gene target is provided for improvement of waterlogging resistance of crops. By constructing an expression vector containing the gene and combining mature technologies such as agrobacterium transformation, the gene can be stably introduced into a target plant, and a pure transgenic plant is obtained.

The invention belongs to the technical field of plant genetic engineering, and particularly relates to an SCRE10 gene for improving rice disease resistance and application of the SCRE10 gene, the base sequence of the SCRE10 gene is shown as SEQ ID NO.1, and the amino acid sequence of the SCRE10 gene is shown as SEQ ID NO.2. Through construction of a dexamethasone induced expression SCRE10 transgenic rice plant, it is found that the transgenic rice can significantly induce PR gene expression and active oxygen outbreak, and the resistance of rice to false smut and bacterial leaf blight can be improved. The invention proves that heterologous inducible expression of the Ustilaginoidea virens SCRE10 gene has the function of positively regulating the disease resistance of the rice, and the SCRE10 gene can be used for improving the disease resistance of the rice, which is of great significance to the creation of disease-resistant germplasm of the rice.

The invention discloses a construction method of a soil microorganism nitrogen metabolism function prediction model, and relates to the technical field of environmental microbiology and agricultural information, and the method comprises the following steps: S1, constructing a spatial-temporal heterogeneity representation engine, and dynamically decoupling a multi-level gradient of a soil environment through an adaptive spatial-temporal mesh generation algorithm; according to the construction method of the soil microorganism nitrogen metabolism function prediction model, the adaptive capacity of the soil microorganism nitrogen metabolism function prediction model in a complex environment is improved, and multi-level environment gradient dynamic analysis from a centimeter-level rhizosphere microdomain to a kilometer-level landscape scale is realized; the problem of cross-scale feature fusion caused by temporal-spatial resolution mismatch of a traditional model is solved, the simplified hypothesis of a traditional statistical model on the synergistic-antagonistic relationship of microbial functional genes is broken through, a dynamic coupling mechanism of a nitrogen metabolism path under environmental disturbance is accurately quantified, and the prediction error is reduced compared with the prior art.

The invention discloses a crested ibis habitat ecological quality trend analysis method and system, and relates to ecological quality monitoring. The method comprises the following steps: S1, constructing an intelligent sensing network, synchronously obtaining multi-source data of a habitat, identifying activity events of crested ibis, and generating a multi-dimensional habitat parameter table; s2, collecting environmental samples, and generating a microbial functional gene abundance matrix through metagenome sequencing and bioinformatics analysis; s3, taking the activity events of the crested ibis as behavior tags, and generating habitat function health indexes by coupling the parameter table and the matrix training machine learning prediction model; s4, performing spatial interpolation and trend analysis based on the habitat function health index to generate an ecological quality space-time evolution graph; and S5, based on the ecological quality space-time evolution graph, performing quantitative analysis by using a spatial differentiation statistical model, and generating a trend analysis report. By fusing multi-source data, real-time dynamic evaluation of habitat ecological quality and quantitative analysis of driving factors are realized, and a direct decision basis is provided for accurate protection.

The invention discloses an application of some functional genes in improving the performance of clostridium for synthesizing ethanol by utilizing one-carbon gas fermentation, wherein overexpression genes NCBI (National Center for Biotechnology Information) are CLJUc04490, CLJUc25060, CLJUc06990, CLJUc22650 and / or CLJUc07720, and expression of inhibition genes CLJUc09160 and / or CLJUc23840 can be used for improving the autotrophic growth capability and the ethanol synthesis yield of clostridium Yangdall when the clostridium Yangdall is fermented by utilizing C1 gas; therefore, the economical efficiency of the clostridium yangdall fermentation is improved.

The invention discloses Aspergillus sp. DLF18 and application thereof, and relates to the technical field of microorganisms, and the preservation number of the Aspergillus sp. DLF18 is CGMCC (China General Microbiological Culture Collection Center) NO.41737. The strain can effectively utilize rice straws and / or bagasse to produce humic acid, and the content of humic acid in each gram of fermentation supernatant after the rice straws are fermented is 16.5%. When the DLF18 fermentation product is applied to crops, the growth condition of the crops can be remarkably improved, and the humus content in soil is increased. Meanwhile, a metagenomics analysis result shows that compared with a control group, after the DLF18 is applied into the soil, the species beta diversity is remarkably changed, and the functional gene abundance and the inter-group difference are remarkably changed. Therefore, the DLF18 has a wide application prospect in the aspects of agricultural straw utilization and soil remediation.

Provided are a Medicago sativa SNP molecular marker combination and a use thereof. The SNP molecular marker combination consists of 61351 SNP molecular markers. The physical positions of the 61351 SNP molecular markers are determined by sequence alignment on the basis of the Medicago sativa reference genome ZM-4 alfalfa genome. The SNP molecular markers have good site specificity, strong versatility, and high polymorphism and can effectively discriminate Medicago sativa germplasms from different sources. A Medicago sativa genome-wide liquid-phase gene chip is prepared from the SNP molecular markers, and can be used for genetic diversity assessment of Medicago sativa germplasm resources, genetic map construction and functional gene mapping, genome-wide association study, etc., providing an important tool and technical support for Medicago sativa molecular design breeding and variety authenticity identification, and achieving important significance for high-quality development of the alfalfa seed industry in China.

The invention discloses Penicillium chrysogenum DLS189 and application thereof, and relates to the technical field of microorganisms, and the preservation number of the Penicillium chrysogenum DLS189 is CGMCC (China General Microbiological Culture Collection Center) NO.41739. The invention further discloses a preparation method of the Penicillium chrysogenum DLS189. The strain can effectively utilize rice straws and / or bagasse to produce humic acid, and the content of humic acid in each gram of fermentation supernatant after the rice straws are fermented is 16.84%. When the DLS189 fermentation product is applied to crops, the growth condition of the crops can be remarkably improved, and the humus content in soil is increased. Meanwhile, a metagenomics analysis result shows that compared with a control group, after the DLS189 is applied into the soil, the species beta diversity is remarkably changed, and the functional gene abundance and the inter-group difference are remarkably changed. Therefore, the DLS189 has a wide application prospect in the aspects of agricultural straw utilization and soil remediation.

The invention discloses a pennisetum purpureum CpERF37 transcription factor and cold-resistant application thereof, and relates to the technical field of plant genetic engineering. According to the invention, the Pennisetum purpureum-sourced ERF transcription factor CpERF37 is cloned and functionally identified for the first time, and heterologous expression verification in a model plant arabidopsis thaliana proves that the Pennisetum purpureum-sourced ERF transcription factor CpERF37 has a remarkable effect on improving the low-temperature tolerance of plants, and functional gene resources related to low-temperature stress response are enriched. The method not only has theoretical innovation, but also has a definite application prospect, and can provide effective gene resources and technical support for cold-resistant improvement of pasture and crops.

The invention relates to a gene ZmILR1 for controlling the size of a corn kernel as well as a molecular identification method and application of the gene ZmILR1, and belongs to the technical field of plant genetic breeding and functional gene research. The ZmILR1 gene encodes an IAA-amino acid hydrolase, mutation of the IAA-amino acid hydrolase causes corn kernels to become smaller, and overexpression of the gene can create a corn material with increased kernel length, kernel width and hundred-kernel weight. A functional molecular marker A1A4 is developed according to the sequence difference of the mutant gene and a wild type gene at the DNA level, and can be used for rapid identification and screening of small-grain corn materials. The invention provides a theoretical basis and an application tool for analyzing a molecular mechanism of the corn grain size and developing molecular marker-assisted breeding and hybrid seed breeding, and provides important gene resources and technical support for high-yield and high-quality molecular breeding of corn.

The invention discloses a tobacco black shank-resistant G24 gene and application thereof in disease-resistant variety cultivation, and belongs to the technical field of tobacco molecular biology and genetic breeding. The nucleotide sequence of the G24 gene is as shown in SEQ ID NO: 1 or has the homology greater than or equal to 95% with the SEQ ID NO: 1; after the expression of the G24 gene is inhibited or the G24 gene is knocked out, tobacco with black shank resistance can lose the black shank resistance, and infected tobacco can obtain the black shank resistance by over-expression of the G24 gene. Based on the gene, the tobacco variety cultivated by the invention has high resistance to the phytophthora parasitica var nicotianae No. 0 microspecies, has excellent agronomic and quality characters, can be used for preparing tobacco products such as cigarettes and the like, and reduces the use of bactericides. The method solves the problems of undefined functional genes and low selection efficiency in existing black shank resistant breeding, and provides a key technology for green prevention and control of tobacco black shank.

The invention provides an agrobacterium rhizogenes-mediated forsythia suspensa hairy root genetic transformation method and application thereof, and belongs to the technical field of plant genetic engineering. The method comprises the following steps: introducing an expression vector into agrobacterium rhizogenes, and mixing with an infection solution to prepare an agrobacterium rhizogenes infection solution; the forsythia suspensa stem is put into the agrobacterium rhizogenes infection liquid to be infected for 0.5-1 h through a vacuum infiltration method, and the infected forsythia suspensa stem is cut into a matrix to be subjected to dark culture and then continues to grow till hairy roots are generated; the OD600 value of the agrobacterium rhizogenes infection liquid is 0.5 to 1.0. The method is suitable for an agrobacterium rhizogenes mediated genetic transformation system of the fructus forsythiae, and the system provides technical support for functional gene research, medicinal component analysis and molecular breeding of the fructus forsythiae, and has important significance for promoting genetic improvement and resource utilization of the fructus forsythiae.

The invention belongs to the technical field of gene editing, and particularly relates to a construction method and application of a needle mushroom CRISPR / Cas9 gene editing vector. The CRISPR / Cas9 gene editing vector for flammulina velutipes is characterized in that the vector takes pFgnpt as a skeleton vector, and further comprises a Cas9 expression cassette and an sgRNA expression cassette; the nucleotide sequence of the Cas9 expression cassette is as shown in SEQ ID NO. 10. The nucleotide sequence of the sgRNA expression cassette is as shown in SEQ ID NO. 11. According to the present invention, with the agrobacterium-mediated transformation technology, the stable expression of Cas9 and sgRNA in the flammulina velutipes body is achieved, the efficient and stable CRISPR / Cas9 gene editing system is established, and the technical support is provided for the flammulina velutipes variety improvement, the functional gene research and the industrial upgrading.

The invention relates to the technical field of animal molecular genetics, molecular marker breeding and aquatic genetic breeding, in particular to a Koi-TAT gene related to golden and silver scale traits of fancy carp, an SNP molecular marker, a primer pair and application. According to the invention, a functional gene highly associated with the Koi gold and silver scale character is found, a specific molecular marker and a detection method are developed on the basis of the gene, and by utilizing the molecular marker and the detection method disclosed by the invention, an individual with excellent gold and silver scale character can be efficiently identified, and the molecular marker is suitable for molecular-assisted selective breeding and early-stage seed selection. The invention provides an important molecular tool for phenotype genetic improvement of aquarium fish, also provides a basis for molecular mechanism research of gold and silver scale formation, and has a wide application prospect.

The invention discloses a banana drought-enduring functional gene MaPUB21 and application of the banana drought-enduring functional gene MaPUB21 in improvement of plant drought-enduring capability. A nucleotide sequence of the gene is shown as SEQ ID NO.2. The invention further discloses a method for preparing the banana drought-enduring functional gene MaPUB21. According to the invention, a silence vector (MaPUB21-pTRV) aiming at the MaPUB21 gene is constructed, and an agrobacterium-mediated method is utilized to carry out instantaneous silence in the Musa communis. Drought tolerance analysis shows that after drought stress treatment, compared with a wild type, the content of malonaldehyde, superoxide anions and hydrogen peroxide of the MaPUB21 silent strain is remarkably reduced, and the content of proline and the activity of peroxidase are remarkably improved. The result shows that the drought tolerance of the plant can be effectively improved by silencing the MaPUB21 gene. The gene provided by the invention provides a new resource for plant stress-resistant molecular breeding, and is of great significance for cultivating drought-resistant plants and improving the utilization rate of drought land.

The invention discloses an application of Micropterus salmoides Piscidin polypeptide in preparation of an anti-fish virus drug. The amino acid sequence of the polypeptide is as shown in SEQ ID NO. 2 or SEQ ID NO. 3. The research finds that the micropterus salmoides Piscidin is an antibacterial peptide with an antiviral function, the polypeptide synthesized by the artificially synthesized micropterus salmoides Piscidin has the characteristic of inhibiting fish DNA virus replication, has a remarkable inhibiting effect on fish iridovirus replication at low concentration, and can be applied to preparation, research and development of fish antiviral drugs. Research of the antibacterial peptide has important scientific value and application value for further research and development of disease-resistant functional gene products.

The application provides a plant antiviral gene XIAN and application thereof in antiviral, and belongs to the field of functional gene technology. The application provides a plant antiviral gene, wherein the plant antiviral gene comprises a conservative domain, the conservative domain is a MAM33 motif, or a conservative domain with more than 80% homology with the MAM33 motif. The application discloses Atxian, NbXIAN, SlXIAN, GmXIAN and GhXIAN genes all containing the MAM33 motif, in corresponding plants, the virus resistance of the mutants after silencing of the genes is weakened, and the virus resistance is improved after overexpression, which proves that the plant antiviral gene can significantly regulate the antiviral phenotype of the plant, so that germplasm with different antiviral phenotypes is created.

The invention provides micropterus salmoides Hepcidin-1 (Ms-Hepcidin-1) and an application of a synthetic polypeptide of the micropterus salmoides Hepcidin-1 in preparation of an anti-fish virus drug. The research finds that the Ms-Hepcidin-1 synthetic polypeptide has a remarkable antiviral effect and is a novel antibacterial peptide with a function of inhibiting fish viruses. The Ms-Hepcidin-1 synthetic polypeptide and the recombinant eukaryotic expression vector of the Ms-Hepcidin-1 synthetic polypeptide can obviously reduce the transcription level of MCP, MMP and DNMT genes and the MCP protein level of LMBV, inhibit the replication of the LMBV and reduce the virus titer, and have an obvious fish virus resisting effect. Moreover, the polypeptide synthesized by Ms-Hepcidin-1 is simple to prepare, low in cost, safe to use and convenient to preserve, can be used as a novel antiviral functional gene product to prepare antiviral drugs for fishes, and has important significance on prevention and control of fish iridovirus diseases.

The invention relates to the technical field of molecular biology, in particular to a reference gene for Chinese olive functional gene expression analysis and application thereof. According to the invention, the reference gene RPN2B which is most stably expressed in fruits of different varieties (lines) of Chinese olives in different development and maturation periods is screened out, and in addition, two reference genes NIFS1 and RPS16 which are only second to the RPN2B are also screened out, so that the method can be used for expression analysis of nutritional quality or other functional genes of the fruits of the Chinese olives of different varieties (lines) in different development and maturation periods; the specificity, the stability and the accuracy of functional gene expression analysis data are remarkably improved, and powerful support is provided for Chinese olive functional gene expression analysis. The invention also provides a special detection primer for detecting the reference gene of the Chinese olive fruit, and the detection primer can quantify the expression quantity and function analysis of the auxiliary gene through fluorescence in the Chinese olive function research, and has high application value.

The invention discloses a method for assisting hawthorn breeding based on phenotypic omics, and relates to the technical field of phenotypic omics assisted hawthorn breeding. Comprising the following steps: S1, acquiring phenotypic data of normally growing hawthorns by using a high-throughput imaging system and a phenotypic analysis system, and detecting and analyzing various characters of the hawthorns; s2, establishing a hawthorn multi-dimensional phenotypic group database, and obtaining hawthorn breeding key character quantitative indexes; s3, constructing a phenotype-genotype correlation model according to the obtained hawthorn breeding key character quantitative indexes, and mining new functional genes to realize early prediction of breeding; and S4, creating a phenotype exponential weighting algorithm for parent matching. The method for assisting hawthorn breeding based on phenotypic omics is established, the problems of long hawthorn breeding period and high cost are solved, and the hawthorn breeding efficiency is effectively improved.

This invention discloses a method for efficient genetic transformation of rice that overcomes genotype dependence and a dedicated culture medium, relating to the field of biotechnology. The dedicated culture medium comprises KCl, KH₂PO₄, MgSO₄·7H₂O, CaCl₂·2H₂O, disodium ethylenediaminetetraacetate, FeSO₄·7H₂O, MnSO₄·H₂O, ZnSO₄·7H₂O, H₃BO₃, KI, CoCl₂·6H₂O, CuSO₄·5H₂O, Na₂MoO₄·2H₂O, glutamine, aspartic acid, arginine, glycine, cyclohexanehexyl alcohol, thiamine hydrochloride, pyridoxine hydrochloride, nicotinic acid, and a carbon source. Using this dedicated culture medium can increase the number of rice cells containing the NiR gene. 375 S 453 The genetic transformation efficiency of haplotype rice varieties is of great significance for overcoming the bottleneck of rice genotype dependence, promoting functional genomics research and molecular breeding.

The invention discloses a corn genome breeding 45K chip and application thereof, the chip covers 44, 637 SNP loci and 27 InDel loci, and the SNP loci are uniformly distributed on 10 chromosomes and part of scaffold of a corn genome and have rich polymorphism. Compared with an existing corn chip, the SNP marker of the 45K chip is derived from re-sequencing results of 507 corn varieties, has better variety representativeness, and contains 925 key functional gene loci for close planting and high yield and 96 corn variety authenticity identification loci; the method can be more effectively used for functional gene identification, genetic diversity analysis, heterosis group division, whole genome selection analysis and variety authenticity identification.

This invention discloses a plant insect-resistant gene and its application and method in plant insect resistance, belonging to the field of functional gene technology. The plant insect-resistant gene of this invention contains the conserved amino acid sequence shown in SEQ ID No. 1, or a conserved amino acid sequence with more than 80% homology to SEQ ID No. 1. This invention verified the function of NtCRF and AtCRF, both containing the conserved amino acid sequence of the GDSL motif, namely, that silencing or mutation significantly reduces resistance to insects; overexpression significantly increases plant resistance to insects. Therefore, it is speculated that genes containing the conserved amino acid sequence of the GDSL motif can be used to increase the difficulty for insects to feed on plant leaves, thereby improving plant insect resistance, and has broad application value.

The application belongs to the technical field of plant genetic engineering, and discloses a functional gene PbCOB.A.1 and application thereof. The in-vitro expressed recombinant protein PbCOB.A.1 can promote pollen tube growth of Rosaceae fruit trees, improve pollination efficiency, and expand the regulation mechanism of non-S factors participating in self-incompatibility reaction in pears. The mechanism of pear pollen tube elongation is researched by using magnetic transfection technology, so that the labor cost can be greatly reduced, and a theoretical basis is provided for pear breeding work.

The invention relates to the technical field of genome assembly, in particular to a medicinal plant genome assembly method and system based on high-throughput sequencing. The method comprises the following steps: acquiring a target sequencing sequence, and screening a function influence sequence; performing repetitive classification on the target sequencing sequence to obtain a non-repetitive sequence cluster and a repetitive sequence cluster, and dividing the repetitive sequence cluster into a functional repetitive sequence and a non-functional repetitive sequence; determining dynamic association strength by combining expression abundance of functional genes, content detection of medicinal components and base overlapping characteristics of adjacent sequences; constructing an association network; and according to the dynamic association strength in the association network, aiming at the functional association type repetitive sequence, the non-functional association type repetitive sequence and the adjacent non-repetitive sequence, respectively carrying out sequence splicing by adopting a differential assembly path to obtain a complete genome assembly result. According to the method, the problems of splicing errors, fragment breakage and redundancy caused by repeated sequences can be solved, and the assembly accuracy and integrity are remarkably improved.

The application belongs to the field of biological information visualization, and discloses a three-dimensional visualization functional gene browser and system based on Z series closed loop coding, which solves the problems of track disorder, arc winding, dependence on scaling and incomplete coding of existing tools. The application constructs Z series closed loop coding, packs genes and non-gene regions into Z0~ZN units, and adapts repeat sequences and ring chromosomes. L-X-Y three-dimensional coordinates are established, 65 standardized character libraries are constructed, and amino acids are labeled in a six-color degenerate system. Modular labeling is adopted, continuous functional elements are integrated into M modules, three types of background colors are used to classify levels, the trunk area and the independent labeling area are displayed separately, and tracks and arcs are abandoned. The system supports Z unit addressing, three-level interaction, module linkage, variation marking, Hi-C double-end alignment and reverse complementary strand switching, realizes full-link visualization from whole genome to single base, and is suitable for genomics and clinical variation analysis.

This invention provides a maize plant architecture regulating gene ZmEXO1 and its application, belonging to the field of maize molecular breeding technology. The amino acid sequence of ZmEXO1 is shown in SEQ ID NO.7. Studies have found that ZmEXO1 can regulate maize leaf angle and plant height; mutants with reduced or silenced ZmEXO1 expression lead to smaller leaf angles and reduced plant height. Therefore, gene editing of the ZmEXO1 gene or genetic breeding improvement using Zmexo1 low-expression mutants can obtain maize germplasm with improved plant architecture, which is of great significance for enriching maize germplasm and breeding high-yielding, dense-planting-tolerant varieties. This invention also provides a Kasp molecular marker and Kasp primers closely linked to ZmEXO1, which can be used for marker-assisted selection breeding and the discovery of related functional genes, enabling rapid screening and identification of maize germplasm containing ZmEXO1-modified molecules.

The invention provides a GMRM (Genome-based Mutant RNA Mapping) method taking a genome as a reference, in particular, the invention provides a method for cloning candidate functional genes of wheat stripe rust resistant plants and an analysis process, and the GMRM method disclosed by the invention can be used for simultaneously cloning two genes with complementary disease-resistant functions, namely Yr6NLR1 and Yr6NLR2. In an example of Yr6, the two disease-resistant genes are closely linked genetically, but the cloning process of the genes does not involve any genetic recombination. Therefore, theoretically, the method provided by the invention can be used for simultaneously cloning a plurality of functional complementary genes (namely genes participating in the same pathway) on the premise that the target gene can generate effective mutation through EMS mutagenesis.

The present invention relates to the technical field of bioinformatics. Specifically disclosed are a machine-learning-based genotype and environment interaction method and the application thereof. The method comprises the following steps: step one, collecting environmental data of each growth and development period within a growth and development cycle of crops; step two, calculating an environmental index within a target growth and development period; step three, calculating a mean value of environmental indices and a comparative mean value of the environmental indices, and determining an environmental index of a growth and development period that has the greatest influence on the mean value of the environmental indices, i.e., an environmental index with the highest correlation; step four, performing calculation to obtain a phenotypic plasticity value of a target gene; step five, calculating a latent functional gene-environment influence parameter; and step six, determining whether a latent functional gene is an important latent functional gene under environmental influence. The present invention can mine critical factors that influence a growth process and phenotypic variation of crops, so as to formulate a cross-environment prediction strategy, optimize a variety selection path and help a breeder make production decisions, thereby advancing the plant breeding progress.

The application discloses a SNP molecular marker related to corn plant height regulation and application thereof. The molecular marker sequence is shown as SEQ ID NO. 1, and the base at the 201bp site from the 5' end presents C / T polymorphism. The application uses a temperate corn inbred line Ye107 with lower plant height as a common father, and crosses with one temperate corn inbred line and four tropical / subtropical corn inbred lines as mother lines to construct a corn multi-parent population with significant plant height difference. GWAS analysis and linkage analysis are used to locate a plant height significantly related site Chr1:SNP-25,296,496 on chromosome 1, and the site can explain 3.59% of the plant height phenotype variation. A functional gene for regulating corn plant height is mined from the site, and qRT-PCR results show that the gene is highly expressed in corn intercalary at V14 stage, and it is proved that the gene is highly related to the regulation of corn plant height. The results of the application provide technical support for efficient and accurate breeding of high-stalk or short-stalk high-yield corn varieties by molecular markers.