(5) The detection and analysis of SNPs can be easily automated. For example, the application of DNA chip technology can achieve large-scale, automated analysis and detection.

11. Briefly describe the basis for constructing a genetic map.

During meiosis, homologous chromosomes undergo exchange, which results in the recombination of genes on the chromosomes. The frequency of recombination between two genes depends on the relative distance between them. Therefore, as long as the exchange value is accurately estimated and the relative position of genes on the chromosome is determined, a linkage map can be drawn.

What are the main steps in constructing a molecular genetic map?

(1) Select molecular markers suitable for mapping and determine parental combinations based on polymorphisms between genetic materials

(2) Establish a mapping population, that is, a segregating population or derivative line with a large number of molecular markers in a segregating state

(3) Analysis of marker genotypes of different plants or lines in a population

(4) Use computer programs to establish linkage relationships between markers

13. What is the difference between a temporarily separated group and a permanently separated group?

Temporary: backcross population, F2 population and its derived populations such as F2:3, etc.

F2 population:

(1) Comprehensive genotype types, large amount of information, and high mapping efficiency

(2) Group construction is relatively time-saving, and a larger group can be obtained in a short time.

(3) Only one generation can be used

(4) The marker ratio of isolated populations derived from distant hybridization is prone to deviate from 3:1, which limits the effectiveness of the population for mapping

Backcross population:

(1) The population has fewer gamete types, making statistical and graphical analysis simpler

(2) The amount of information provided is less than that of the F2 population

(3) Cannot be used for multiple generations

Permanent:

Recombinant inbred line (RIL) populations are formed by hybridizing two varieties to produce an F1 line, which is then self-pollinated to produce an F2 line. From this F2 line, hundreds of randomly selected individual plants are self-pollinated, each plant being planted with only one seed, until the F6 to Fn generations are reached, resulting in the formation of hundreds of recombinant inbred lines.

Doubled haploid (DH) population:

(1) The DH population is equivalent to an F2 population that no longer separates and can be preserved for a long time.

(2) Construction of DH population requires tissue culture technology and chromosome doubling technology

(3) When the number of individuals in the DH population is small, the amount of information provided is often lower than that of the F2 population

14. Can the distance on the genetic map reflect the actual distance between genes on chromosomes?

What types of populations are used for molecular marker genetic mapping?

Temporarily separated groups and permanently separated groups

Do dominant and codominant markers segregate in the same proportion in the F2 population? Why?

Different. Dominance: 3:1, Co-dominance: 1:2:1

What are the commonly used application software for plant genetic mapping?

MAPMAKEREXP, JoinMap, etc.

What are the main methods for locating genes for quality traits?

Near-isogenic line analysis

Segregating group mixture analysis method: BSA method based on trait expression, BSA method based on marker genotype, extreme group-recessive group method

Basic strategies for finding molecular markers for quality traits using near-isogenic lines.

Compare the marker genotypes of the recurrent parent, NIL, and donor parent. If the NIL has the same marker genotype as the donor parent but different from the marker genotype of the recurrent parent, the marker may be linked to the target gene.

Principles of using segregating population mixture analysis to locate genes for quality traits.

(1) BSA method based on trait phenotype: In the mapping population, individuals or strains are divided into two groups based on the relative differences in the target trait phenotype, and the DNA is mixed to form relative DNA pools.

(2) BSA method based on marker genotype: The genotypes of individuals in a population are determined using molecular markers on both sides of the target gene, and individuals with the same genotype are selected to form groups.

(3) Extreme group-recessive group method: ① Use extreme groups to identify the chromosome segment where the target gene is located

②Use extreme individuals (recessive groups) with recessive phenotypes to determine the location of gene loci on the molecular marker linkage map

Give an example of using segregant population mixture analysis to locate genes for quality traits. (I'm really not sure if this answer is correct...)

Marking and mapping of genes resistant to downy mildew in lettuce, resistance to rice gall midge, and resistance to rice blast in rice

What are the characteristics of quantitative traits?

(1) A large number of genes involved

(2) Sensitive to environmental changes

(3) The trait shows quantitative changes

(4) The trait distribution is a continuous approximate normal distribution

23. What are the main methods for QTL mapping?

Interval mapping, multiple regression, and exact mapping

QTL mapping methods: single marker analysis, interval mapping, composite interval mapping

What is the basic principle of single marker analysis?

If a marker is linked to a specific QTL, then in the offspring of a hybrid, there will be a certain degree of cosegregation between the marker and the QTL. Consequently, different genotypes of the marker will have differences in the distribution, mean, and variance of the (quantitative) trait. Examining these differences can infer whether the marker is linked to the QTL.

What are the advantages of interval mapping compared to single-marker analysis?

More accurate and effective

What is the most important QTL localization method at present?

What is the LOD value? What is the significance of the LOD value?

Concept: The logarithm of the ratio of the probability of the presence of a QTL to the probability of the absence of a QTL

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