Plant Breeding: Quiz 3 – Flashcards
Unlock all answers in this set
Unlock answers| Anther culture |
| A method of obtaining haploids in the doubled haploid method. Used in tobacco and rice. |
| Artificial hybridizaiton |
| Involved emasulation of the female parent and hand-pollination. |
| Art |
| Creation of something from your imagination. Plant breeding is an art. |
| Atlas |
| The highest yielding variety in the mixture in the experiments by Suneson and Wiebe. |
| Backcross |
A4*/B A type of cross. The donor and recurrent parents are crossed, and the progeny crossed to the recurrent parent for multiple generations. Advantages: Requres few plants, known and desirable recurrent parent phenotype is recovered, rapid, predictable, repeatable, breeding program can be independent of the environment. Disadvantages: does not permit selection of new combinations of genes, linkage drag may be a problem. |
| Background selection |
| Marker-assisted back-crossing used to recover the parent genome. |
| Base |
| In the RIPE system, populations which are 50% elite. |
| Bergner |
| Proposed the double haploid method in 1924 after studying Jimson weed. |
| Bi-Parental crosses |
| Backcrosses, bulk, pedigree, single seed descent. Limited in their ability to combine genetic traits from several sources. |
| Bulk method |
A method of selection for self-pollinated crops following a cross, with no early generation selection. Developed by Nillson-Ehle. The simplest line development method. Progeny testing is performed only after acceptable homozygosity is achieved. Advantages: No record keeping until F4, low labour, allows natural selection (biotic, abiotic, competition) Disadvantages: Natural selection is not always an advantage: progeny are lost due to early sampling. 1. Cross parents to obtain F1. 2. Allow F1 to self-pollinate to produce F2. 3. Grow 1000 F2 plants, select the best plants or allow natural selection. Obtain a bulk of F3 seeds. 4. Grow 1000 F3 plants, select the best plants or allow natural selection. Obtain a bulk of F4 seeds. 5. Grow 1000 F4 plants, select best plants or allow natural selection to occur. Make single plant selections for F5 seeds. 6. First year trials of 100 F5 lines at 1 - 3 locations. Select the best 20 plants, save selfed seed. 7. Second year trials of 20 F6 lines at many locations. Select the best 5 plants, save selfed seed. 8. Third year trials of 5 F7 lines at many locations. Release a new cultivar.
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| Business |
| Plant breeding is a business. Many corporations are involved in the profitable enterprise of plant breeding. |
| Chain cross |
| A type of cross. Produces 8 different progenies. |
| Choosing objectives |
| The first step in developing a self-pollinated cultivar. Consider current and future markets. Is the product the seed, seed component, plant, or specific compound. What is the environment? Increase productivity or quality. |
| Chromosome elimination |
Hordeum bulbosum method A method of obtaining haploids in doubled haploid method. |
| Colchicine |
| Used in double haploid method to double the number of chromosomes in haploid plantlets. |
| Conical cross |
A/B//C/D/3/E/F//G/H A type of cross. A cross of two double crosses. |
| Crop Science |
| A journal which used to publish cultivar registrations. Created the Journal of Plant Registrations. |
| Cultivar |
| A plant population selected for desirable characteristics that can be maintained by propagation. Must have identity and reproducibility. |
| Donor parent |
| In back-crossing, the parent with the desired gene. It is crossed only once into the backcross, at the beginning. |
| Double cross |
A/B//C/D A type of cross. Two sets of parents are crossed, and the progeny crossed. |
| Doubled haploid |
A method of selection for self-pollinated crops proposed by Bergner. Theoretical until the development of in vitro systems in the 1970's. Follows a cross, with no early generation selection. Haploid plantlets are produced by ovary culture, anther culture, chromosome elimination, microspore culture, or in vivo systems (spontaneous, semigamy, and polyembryony). Chromosomes are doubled by cochicine to produce homozygosity. Advantages: Quick, small population size, doubled haploids are extremely uniform, selection is very efficient, favourable linkages are preserved. Disadvantages: Specialized personnel and infrastructure are required, efficiency depends on genotype, and unfavourbale linkages are preserved. 1. Cross parents to obtain F1. 2. Use lab methods to double the chromosome number in F1 to produce doubled haploid F2. 3. Grow F3 plants and evaluate and select: homozygosity is achieved.
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| Early generation testing |
| Evaluation of lines at an early generation of selfing so that further phenotyping can be focused on lines that are most promising. |
| East |
| In 1916, studied the effect of selection during inbreeding on the tobacco corolla tube length. Found that the longer you inbreed with selection, the more plants have phenotypic values close to parental values. F1 will be an intermediate between parents, but homogenous. F2 will have greater variation than F1 or the parents. Segregation and recombination occurrs. |
| Elite |
| In the RIPE system, populations which are 93.25% elite. |
| Emasculation |
| A part of artificial hybridization. Removal of the anthers from the female parent. |
| Evaluating and selecting superior homozygous lines |
| The fifth step of developing a self-pollinated cultivar. |
| Experimental strains |
| Varieties that are not released to the public, only used in breeding programs. |
| F1 |
| The product of a cross between two parents. If the parents are homozygous, F1 is heterozygous, and the population is homogenous. |
| F2 |
| The progeny of F1. Heterozygous and heterogeneous. |
| Fixed genes |
| Genes which are the same in both alleles. F1 is homozygous for these genes. |
| Food security |
| A reason for plant breeding. Food is a human right. Protects the right of people to feed themselves with dignity: sufficient food that meets dietary needs is available with means to access it. |
| Foreground selection |
| Marker-assisted back-crossing used to track the gene being introgressed. |
| Formation of segregating populations |
| Variation can be obtained by introducing a new population, mutations, somaclonal variation, plant transformation, or hybridization. |
| Goulden |
| Proposed single seed descent method in 1939 for use in wheat. |
| Harlan and Martini |
| In 1983, studied barley and found that some plants could be favoured in one environment and out-competed in another. Studied varieties in ten locations for 4 - 12 years. |
| Heterogeneous |
| Populations are genetically diverse. |
| Heterozygous |
| Having two different alleles at a locus. |
| High |
| In the RIPE system, populations which are 87.5% elite. |
| Homogenous |
| Populations are genetically uniform. |
| Homozygous |
| Having two of the same alleles at a locus. |
| Hybridization |
| The most common method of producing new variation in a population. Parents must differ genetically for traits of interest. |
| Ideotype |
| The target phenotype of plant breeding. |
| Inbreeding to an adequate level of homozygosity |
| The fourth step of developing a self-pollinated cultivar. The numbers of generations of inbreeding before selection, and management method during inbreeding must be decided. |
| Intermediate |
| In the RIPE system, populations which are 75% elite. |
| Introductions |
| In the RIPE system, populations which are 0% elite. |
| Jimson weed |
| Studied by Bergner in 1924, in experiments that led him to propose the doubled haploid method. |
| Johannsen |
| Postulated the Pure Line Theory. |
| Journal of Plant Registration |
| Created by Crop Science in 2006. Publishes cultivar registrations. |
| Landrace |
| Heterogeneous, homozygous. In the 1930's they selected varieties from landraces. |
| Line |
| Derived from a single plant selection. |
| Marker-assisted back-crossing |
| Backcrossing using molecular markers to phenotype. Used for foreground selection or background selection. |
| Mass selection |
A method of selection for self-pollinated crops using existing variation. Plants are chosen from a genetically diverse population on the basis of phenotype. Seed is composited without progeny testing. The easiest method of selection in self-pollinating crops. The end product doesn't differ in performance from the original population, but it is more uniform. Develop a new culivary by improving average performance of the population. Objectives: Purify a mixed cultivar or plant population by propagating plants with similar phenotype, and develop a new cultivar by improving average performance of the population. |
| Microspore culture |
| A method of obtaining haploids in doubled haploid method. |
| Modified bulk-pedigree |
| A method of selection for self-pollinated crops following across, with early generation selection. |
| Modified single-seed descent |
Similar to SSD, but instead of one, 2 - 3 seeds per plant are used for the following generation. Progeny from individual lines is maintained separately during each generation of increase. Advantages: Reduces selection efforts prior to F6, easy, no natural selection, well suited to winter/off-season nurseries. Disadvantages: More plants than SSD, no elimination of undesirable alleles early on, no natural selection, genetic combinations may be lost if population sizes are too small. |
| Molecular marker |
| A polymorphism in the DNA. Can be a size difference, or a sequence difference. |
| Natural selection |
| In bulk selection, plants that are most adapted to growing conditions are naturally selected. This effect is not neglicible, as shown by experiments by Suneson and Wiebe. |
| Near isogenic line (NIL) |
| The result of a backcross. It is identical to the recurrent parent, except for one desired gene which was introgressed in from the donor parent. |
| Nilsson-Ehle |
| Developed bulk method in Svalof, Sweden in 1908. |
| Ovary culture |
| A method of obtaining haploids in doubled haploid method. |
| Pedigree selection |
A method of selection for self-pollinated crops, following a cross, with early generation selection. Follows hybridization. Progeny testing is an essential feature. Breeder maintains a family structure by growing progeny of each selected single plant in progeny rows. Single plant selections in early generation, and row selection when homozygosity is reached. Was popular in the 80's and 90's, but was replaced with bulk method. Advantages: Traces the lines of each cultivar back to an F2 plant (allows breeders to exploit variation within prior generations), artificial selection can be imposed in each generation, breeder can use their "breeder eyes". Disadvantages: Additional work is needed to keep track of pedigree lines, more resources are required. 1. Cross parents to obtain F1. 2. Allow F1 to self-pollinate to obtain F2. 3. Grow 1000 F2 plants. Screen for traits with high heritability. Save selfed seeds from 200 plants. 4. Grow 200 F3 lines in progeny rows. Select the best 50 lines. Save selfed seeds from the best 1 - 2 plants in each row. 5. Grow 50 - 60 F4 lines and sublines. Select the best 15 lines. Save selfed seeds from the best 1 - plants in each row. 6. Trials of 15 T5 lines at 2 - 3 locations. Select the best 8 lines. Saved self seeds. 7. Trials of 8 F6 lines at more locations. Select the best 4 lines. Select selfed seeds. 8. Trials of 4 F7 lines at more locations. Release new cultivars. |
| Phenotypic back-cross breeding |
| Standard procedure to introgress major genes into other germplasm. The donor parent and recurrent parent are crossed, and back-crossed with the recurrent parent, resulting in a near-isogenic line. If the gene is recessive, progeny testing is required after every generation. |
| Plant breeding |
| The genetic improvemnet of plants for human benefit. A science, art, business, and technology. Food security is important. An act of throwing things away: shifts the population into the right direction. |
| Plantlets |
| Haploid plants produced in doubled haploid method. |
| Pollination |
| Transfer of pollen from the male parent to the stigma of the female parent. A part of artificial hybridization. |
| Polyembryony |
| An in vivo mthod of obtaining haploids in doubled haploid method. Used in peppers and asparagus. |
| Preparing seed stocks for commercial distribution |
| The sixth step of developing a self-pollinated cultivar. |
| Princess |
| The variety of common bean that Johannsen used in his experiments. |
| Progeny testing |
| Determining a plant's genotype by looking at its progeny. Plant a row of each of the progeny. |
| Pure line |
| Homozygous, homogenous. Progeny descended from one self-pollinated, homozygous plant. |
| Pure line selection |
A method of selection for self-pollinated crops using existing variation. Isolating pure lines from a mixed population. 1. Grow 1000 plants, screen for traits with high heritabilty, save selfed seeds from 100 selected plants. 2. First year trials of 100 pure-lines at 1 - 3 locations. Select the best 20 pure lines. 3. Second year trials of 20 pure lines at many locations. Select the best 5 pure lines. 4. Third year trials of 5 pure lines at many locations. Release new cultivars. |
| Pure Line Theory |
| The action of selection cannot go beyond known limits - it must stop when the purification of the most strongly divergent line is complete. Postulated by Johannsen, based on his work selecting for high and low seed weight in Princess common beans. After the first cycle of selection within the variety, there was no change in seed weight. All variation is from environmental interactions alone. |
| Pyramid cross |
Convergent cross A type of cross. All possible ways of a conical cross between 8 parents is tried for 8 sets of F1. |
| Recombinant inbred lines (RIL) |
| Inbred, homozygous lines. |
| Recurrent Introgressive Population Enrichment system (RIPE) |
| Male-sterility faciliated recurrent selection in barley. There are introductions, base, intermediate, and high populations. A male sterility allele is employed, tightly linked in coupling phase with the sex 1 locus. Genotype has shrunken in the endosperm: all shrunken seeds are male-sterile. Only the male-fertile seeds are used and selected during inbreeding phase. Large numbers of crosses can be made with ease because emasculation is unneccessary. 500 - 700 crosses can be made in a week. Introduces a broad range of germplasm. |
| Recurrent parent |
| In a backcross, the parent that lacks the desired gene, but may be an elite variety. It is backcrossed many times in the backcross. |
| Red 5 |
| The first variety of wheat released. Developed in Ontario. Brought from Scotland by a family of immigrants. It was a winter wheat but they planted it in the spring. Only one plant came up, and it became the ancestor of all spring wheat in Canada. A pure line. |
| Repeated inter-mating |
| Can combin traits from several sources. Breaks up linkages among groups of loci, enabling a new genetic combinations. |
| Response to selection (RS) |
| Genetic gain. |
| Science |
| Testing a hypothesis to generate new knowledge. Plant breeding is a science. |
| "Seed morgue" |
| A term used to describe seed banks, because breeding programs tend to avoid non-elite germplasm. |
| Segregation |
The portion of individuals in a population which are heterozygous. = (?)m m = the number of generations of self-fertilization = (generation number - 1) |
| Selecting parents |
| The second step in developing a self-pollinated cultivar. Depends on the objectives. |
| Selection intensity |
| The portion of the population which is selected. Usually 10% - 20%. |
| Semigamy |
| An in vivo method of obtaining haploids in doubled haploid method. Used in cotton. |
| Simple cross |
A/B A type of cross. Two parents are crossed. |
| Single seed descent (SSD) |
A method of selection for self-pollinated crops proposed by Goulden. Follows a cross, with no early generation selection. A form of bulk method. Progeny testing is postponed until acceptable homozygosity is reached. Selections can be as good as other systems. Advantages: Each F2 plant is represented in the progeny test. The varietion of F2 is well represented, and advese effect of natural selection is minimized. Not much space is required: possible to grow multiple generations indoors. Disadvantages: No selection during early generations, harvest may be more difficult than conventional bulk. 1. Cross parents to obtain F1. 2. Allow F2 to self-pollinate to produce F2. 3. Grow 1000 F2 plants. Save one seed from each of 150 selected plants. Bulk the F3 seed. 4. Grow 150 F3 plants. Save one seed from each plant. Bulk the F4 seeds. 5. Grow 150 F4 plants. Save F5 seeds from 100 individual plant selections. 6. First year trials of 100 F5 lines at 1 - 3 locations. Select the best 20 plants. Save selfed seeds. 7. Seocnd year trials of 20 F6 lines at many locations. Select the best 5 lines. Save selfed seeds. 8. Third year trials of 5 F7 lines at many locations. Release a new cultivar. |
| Sister lines |
| Two varieties that are from the same cross. Can be very different. |
| Spontaneous |
| An in vivo method of obtaining haploids in doubled haploid method. Used in maize. |
| Spreader row |
| A row of disease-susceptible variety planted next to a line in a breeding program. Imposes a disease selection pressure on the population. Mist irrigation may also impose a disease selection pressure. |
| Suneson and Wiebe |
| Did experiments in 1942 that showed that natural selection had considerable effect in bulk method selection. Atlas was the highest yielding variety in the mixture. |
| Technology |
| Physical application of knowledge. A new variety is a new technology. |
| Tree-way cross |
A/B//C A type of cross. Two parents are crossed, and the progeny are crossed to a third parent. |
| Variety |
| A plant population with identity and reproducibility, but is not cultivated. A subdivision of species, for taxonomic classification. A group of indivual plants that are genetically distinct from other groups of plants within the species. |
