Pedigree Method and Single Seed Descent method

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WELCOME Ajinkya Rajendra Ambavane Regd. No.-2153 DEPARTMENT OF AGRICULTURAL BOTANY 1

Seminar on Pedigree Method and Single Seed Descent method: 

Seminar on Pedigree Method and Single Seed Descent method Slide no -2 2

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Pedigree Method Slide no -3 3

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Meaning of word “ Ped -i- gree ” 1 . a. A line of ancestors; a lineage. b. A list of ancestors; a family tree. 2. A chart of an individual's ancestors used in plant and animal genetics to analyse Mendelian inheritance of certain traits, especially of familial characteristics . 3. A list of the ancestors of a animal & plant. “The pedigree may be define as a description of the ancestors of an individual and it generally goes back to some distance of ancestor or ancestors in the past” Slide no -4 4

History: 

History Practice of the pedigree method predates rediscovery of Mendel’s work Vilmorin used the pedigree method in France in the 1830’s Institute at Svalof - used pedigree type breeding in the 1880’s Slide no -5 5

Nillson: 

Nillson Represented families by one or more plants Noted that when harvested seed came from only one plant, the progeny were much more uniform Came to call this the “system of pedigree” Slide no -6 6

The Pedigree Method: 

The Pedigree Method What is pedigree method? It is a type of hybridization technique in self pollinated crops. In pedigree method superior types are selected in successive segregating generation , & a record is maintained of all parent- progeny relationship . Individual plant selection continued till the progeny become virtually homozygous, & the show no segregation . Slide no -7 7

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In pedigree method, a detail record of the relationship between selected plant and progenies is maintained. As a result, each progeny in every generation can be traced back to F 2 generation from which is originated. Pedigree record Slide no -8 8

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The pedigree record may be kept by several ways, but it should be simple & accurate. Generally, each cross is given a number : first two digit of the number refer to the year in which cross is made, and remaining digit denote serial number of the cross in that year. For example, the number 8911denotes the cross number 11 in the year 89 Maintenance of pedigree record Slide no -9 9

Begin with the F2 generation: 

Begin with the F 2 generation After the cross has been made in selected parents, & F 1 plant has been grown, seed produce on it are collected in bulk. On sowing, these seeds give rise to F 2 population where segregation appear. Selection of desire type of plant start from F 2 population Slide no -10 10

F2 plant selection: 

F 2 plant selection Identify best plants, e.g. short, early, clean, vigorous Tag or spray paint plants to signify selects Pull or dig up whole plants at maturity to provide plenty of F 2:3 seed Slide no -11 11

Characters for Selection: 

Characters for Selection High heritability desirable Amenable to visual selection Traits that can be evaluated in individual plants or progeny rows Number of plants grown must be adequate for number of traits evaluated Slide no -12 12

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In Ist year: Cross has been made between selected parents In IIst year : Raising of F 1 plants to produce enough F 2 seeds F 2 : Make IP selections May apply artificial or natural stress screens F 3 : IP  Individual plant are again selected harvested, threshed & kept separately F 4: IP  PR Make IPs within best rows F 5 : Select best and uniform rows Make bulk rows within the best & uniform progeny F 6 : Begin performance testing Uniform & promising progenies are selected & bulk harvested for evolution in field trials F 7-n : Expand performance testing and release Repeated trial for 3-5 years at several location , and released as variety Pedigree Method : General Outline Slide no -15 15

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If selection is effective, inferior types are discarded in the individual plant phase and before strain testing Selection each season involves a different environment which provides for the effective selection of stable genotypes Genetic relationships are known and can be used to maximize genetic variability among retained strains Advantages Slide no -16 16

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Can’t be used in environments where genotypic variation of interest is not expressed, thus eliminating off-season nurseries (not a major obstacle) Tremendous record keeping Subjective nature of IP selections, thus experience of the one making the IP selections is important Requires more land and labor than, say, the bulk or mass methods Disadvantages of the Pedigree Method Slide no -17 17

Some other points: 

Some other points It is very popular method for self pollinated crop. Most of verities in self pollinated crops are developed by this method It take about 12 to 14 year to develop a variety by pedigree method. But with the help of ‘off season nursery’, every year 2 generation can be grown & time taken can be shortened from 12 to 6 year. Slide no -18 18

Achievements: 

Achievements A large number of varieties , have been developed by pedigree method in crop like whet, rice, barley, pulses, oilseed, cotton, tobacco, jowar, vegetables etc. Most of NP wheat (NP52, NP80-5, NP120, NP125 etc.), K65 (C591×NP773). Rice :-Jaya, Padma, Bala, Cauveri, Karuna, Krisna, Ratna, Sabarmati. Cotton :- Laxmi Tomato :- Pusa Earlu Dwarf Slide no -19 19

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Pedigree trial & seed multiplication system Slide no -20 20

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SINGLE SEED DESCENT METHOD Slide no -21 21

Single Seed Descent method: 

Single Seed Descent method SSD is a modification of bulk method. This is the classic procedure of having a single seed from each plant, bulking the individual seeds, and planting out the next generation. With this procedure one or two seed are collected from each F 2 plant and then bulk to grow F 3 generation Slide no -22 22

History: 

History This method was first suggested by Goulden in 1941(without calling it SSD) Grafius (1965) and Brim (1966) refine and advocated it as Single Seed Descent Method Slide no -23 23

Procedure: 

With this procedure one or two seed are collected from each F 2 plant and then bulk to raised F 3 generation Similarly in F 3 and subsequent generation one random seed is selected from every plant Seed is bulk to raised next generation. This procedure follows till F 5 or F 6 generation when plant become nearly homozygous. Procedure Slide no -24 24

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General outline : Single Seed Descent Method Action Grow F 1 plants, harvest all F 2 seeds per plant Grow F 2 population , harvest one seed per plant Grow F 3 population , harvest one seed per plant Grow F 4 population , harvest one seed per plant Space-plant to grow F 5 select best single plants Grow F 5 -derived plant rows In the F 6 generation (F 5:6 ) Yield Test in F 7 (F 5:7 rows) Yield Test in F 8 (F 5:8 rows) Yield Test in F 9 (F 5:9 rows) Large-scale seed increase for variety release Slide no -25 25

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1. Single seed (SSD) From each plant in a segregating population, e.g. F 2 , one selfed seed is obtained and bulked within parental population 2. Single hill (SHD) Several segregating plants, e.g. F 2 , are grown in a “hill” or grouping & at maturity, a number of seed are harvested from each hil 3. Multiple seed (MSD) Simply means that the breeder collects > 1 seed per plant Types of Single Seed Descent Slide no -26 26

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General advantages easy to maintain populations No natural selection pressure Well suited to greenhouse or winter nursery advancement of generation. Require very little space, effort, and labour. General disadvantages 1. Artificial selection is based on “pure line” or individual plants and not on the progeny performance. THUS there is no accumulation of desirable progeny. 2. Natural selection CAN NOT influence the population in a positive way Single Seed Descent Slide no -27 27

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Achievements Barley variety :- Glacier, Arivat , Beecher, Gem ( Atlas×Vaughan ) Indian mustard : Narendra rai Slide no -28 28

References : 

References Introduction to Plant breeding by R. C. Chaudhary Principles of Plant breeding by R. W. Allard Plant breeding Principles and Method by B. D. Singh Internet Source Slide no -29 29

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Thank you Slide no -30 30