1 / 36

Plant breeding and genetics

1. Plant breeding and genetics. Biologia fiorale. Stimma Ovario Nettari Antere Petali. 2. 3. Eredità Mendeliana. La prima legge di Mendel – segregazione – è il risultato diretto della separazione degli omologhi in cellule distinte durante la prima divisione meiotica

iphigenie
Download Presentation

Plant breeding and genetics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 1 Plant breeding and genetics Biologia fiorale Stimma Ovario Nettari Antere Petali

  2. 2

  3. 3 Eredità Mendeliana • La prima legge di Mendel – segregazione – è il risultato diretto della separazione degli omologhi in cellule distinte durante la prima divisione meiotica • La seconda legge di Mendel – assortimento independente – deriva dalla separazione indipendente di differenti coppie di alleli su cromosomi omologhi

  4. 4 Eredità Mendeliana B A b Accoppiamento Segregazione Assortimento Indipendente a B A b a b B A A B a a b

  5. 5 Che cosa è il genotipo della F1 ? Come segregherà nella generazione F2 ?

  6. 6 X Green, round yy RR Yellow, wrinkled YY rr Cosa sono i genotipi e i fenotipi delle generazioni F1 ed F2 ?

  7. 7 Eredità Mendeliana • Risultati di incroci di pisello con parentali che differiscono per 1 carattere • Prima legge : la segregazione Fenotipo parentali F1 F2 F2 Ratio Round/wrinkled round 5474:1850 2.96:1 Yellow/green yellow 6022-2001 3.01:1 Purple/white purple 705:224 3.15:1 Inflated/pinched inflated 882:299 2.95:1 Axial/terminal axial 651:207 3.14:1 Long/short long 787:277 2.84:1

  8. 8 Inbreeding • L’Inbreeding è dovuto all’incrocio tra individui molto imparentati grazie ad un comune genito-re ancestrale e sono individui presi a caso dal-la popolazione • La sua estrema espressione è il selfing

  9. 9 Scopi dell’inbreeding • Mantenimento di specifici genotipi • 3n genotipi 2n genotipi • n = no. of genes • ex: AA, Aa, aa AA , aa • Selezione contro i recessivi

  10. 10 Outcrossing • Incrocio causale – promuove la diversità • Eterozigosità • L’esempio estremo è l’ibrido F1 (Aa)

  11. Auto-Incompatibilità 11 • Rinvenuta in molte specie, inclusa la Brassica spp. • Il locus S è Multiallelico (> 60 alleli !) • Tutti i pollini di una pianta hanno la stessa reazione di incompatibilità S1S3 S1S3 S1S3 NO NO S2S4 S1S2 S2S3 Incompatibile Incompatibile Compatibile

  12. 12 Male Sterility Systems • Genic • Nuclear gene conditions sterility • Sterility usually recessive, often msms • Cytoplasmic • Non-nuclear genes responsible for sterility • Pollen parent has no influence on fertility or sterility • Not useful for seed crops • Cytoplasmic-Genic • Non-nuclear genes cause sterility, nuclear restores fertility • Two-gene system required for sterility / fertility • Useful for seed-propagated crops

  13. Inheritance of Male Sterility 13 • Genic • msms = sterile • msms X MsMs • Msms X Msms • msms X Msms • Cytoplasmic • S X F • Cytoplasmic-Genic • Smsms = sterile • NMSMS = fertile • Nmsms = fertile • SMsms = fertile All Msms; 100% fertile 3:1 segregation; 25% sterile 1:1 segregation; 50% fertile All progeny sterile due to maternal inheritance Only Smsms conditions sterility Fertility with either N cytoplasm or dominant Alleles at nuclear restorer locus (Ms)

  14. 14 Use of Genic Male Sterility Fertile parent MsMs msms x MsMs Msms • Segregate 3:1, 25% sterile • PROBLEM IS - HOW DO YOU IDENTIFY and maintain msms steriles ?

  15. 15 Use of Cytoplasmic Male Sterility • Must use sterile as female parent, • all progeny are sterile S X F S

  16. 16 Use of Cytoplasmic-Genic Sterility • Inheritance of CMS system Smsms x Nmsms Smsms only, all sterile Smsms x NMsMs SMsms only, all fertile SMsms x NMsms 1 Smsms sterile 2 SMsms fertile 1 SMsMs fertile S msms msms F S N F F Ms- Ms- S N

  17. 17 Variation in ploidy • General concepts: • Genome is basic unit of chromosomal makeup • Chromosomes of a genome inherited together in a ‘normal’ meiosis and mitosis • Chromosome number of the gametophyte is ‘n’ • Chromosome number of the sporophyte is 2n • Base number of chromosomes (one of each pair) is ‘x’ • If 2n=2x=22, gametes are n=x=11 (diploid) • If 2n=4x=44, gametes are n=2x=22 (autotetraploid) • In a monoploid, 2n=x=11 • In a triploid, 2n=3x=33

  18. 18 Ploidy Configuration • Haploid • 1x • Diploid • 2x • Tetraploid • 4x • Triploid • 3x

  19. 19 Autoploidy • Monoploid A • Diploid AA • Triploid AAA • Tetraploid AAAA • Pentaploid AAAAA • Hexaploid AAAAAA • Duplication: 2n=2x...........2n=4x

  20. 20 Genetics of Autoploidy • Autotetraploid: 5 different genotypes • Gametes are 2x • Nulliplex aaaa • Simplex Aaaa • Duplex AAaa • Triplex AAAa • Quadriplex AAAA

  21. 21 Banana • Banana typically autotriploid and sterile • Low fertility is desired to make a seedless banana • Fruit is produced parthenocarpically

  22. 22 Allopolyploidy • Typical diploid inheritance patterns because of lack of pairing of chromosome sets • Possibility of multiple alleles in different genomes • Can result in unique nuclear-cytoplasmic interactions • Case of cotton demonstrates value of D genome to cultivated types despite poor performance of D genome per se • Dihaploid AB • Allotriploid ABC, AAB, ABB • Allotetraploid AABB • Allopentaploid AABBC • Allohexaploid AABBCC

  23. 23 allopolyploidy A B D Separate genomes come together, but each Genome has normal diploid pairing and segregation

  24. 24 Triangle of U B. rapa n=10 AA B. juncea n=18 AABB B. napus n=19 AACC B. oleracea n=9 CC B. nigra n=8 BB B. carinata n=17 BBCC

  25. 25 Brassciaoleracea and rapa

  26. 26 Quantitative inheritance • Quantitative traits • Continuos variation (normal distributions) • Often characterized as being affected by many genes expression of which is modified by the environment • Qualitative traits • Often single gene Mendelian traits • Segregate into discrete classes

  27. 27 Distribution of Quantitative trait(s) * Mean * Variance * covariance

  28. 28 Pedigree selectionHow to do it • Pedigree, as the name implies, provides a record of the lines of descent of all individuals in each generation. • The accumulation of information is important when decisions need to be made regarding keeping or eliminating a line.

  29. 29 Yellow butternut

  30. 30 Pedigree selection Requirements • Two parents • Choice of parents is critical, as you invest a lot of time and resources in each pedigree pop’n • Complementary in strengths and weaknesses AAbb x aaBB

  31. 31 Pedigree selection Implementation P1 AAbb x P2 aaBB F1 AaBb F2 (9 genotypic classes) 3n A_B_ AAB_ A_BB aabb F(4 genotypic classes) 2n AABB AAbb aaBB aabb

  32. 32 Pedigree selection Implementation • Self pollinate each F2 plant, and grow out F3 families. Self pollinate selected plants. • Select among and within families in early generations

  33. 33 Pedigree selection F2 plants 1/4 1/2 1/4 BB Bb bb BB BB BB bb BB Bb Bb bb BB Bb Bb bb BB bb bb bb Individuals F3 Families

  34. Pedigree selection 34 Outline F1 Select among F2 individuals F3 Families Select among and within

  35. 35 Features of Pedigree selection • After inbreeding and testing lines can be bulked and released as cultivars. • Its fun and flexible • When a superior family is identified, you can trace back in the pedigree and select in earlier generations

  36. 36 Negative features • Maximum productivity is established in F2 generations. • From AaBbCcdd cannot select AABBCCDD • Minimum recombination • No opportunities to cross aabbCCDD x AABBccdd

More Related