1. On behalf of „New Areas in Plant Breeding PhD (Nr. 740458)” June 19 2015 Some comments on Autotetraploidy W. Link

2. Examples for autotetraploid species Dactylis glomerata 2n=4x=28 Bromus hordeaceus 2n=4x=48 Medicago falcata 2n=4x=32 Solanum tuberosum 2n=4x=48 Ipomea batatas 2n=6x=30

3. For instance … Research review Parisod, Holderegger, Brochmann, 2010. Evolutionary consequences of autopolyploidy. New Phytologist 186, 5-17. Special Issue: Plant polyploidy

4. DIPLOID

5. Microspore 1st Meiotic 2nd Meiotic mother cell division division f = 0 f = 0.3 DIPLOID!

6. Gametes of diploids do not carry any ‚shadow, echo, memory‘ of the inbreeding status of their parental plants. DIPLOID Equatorial plate

7. DIPLOIDS Matings of non-related parents yield offspring which is non- inbred! This is true, whether these parents themselves are inbred or not. With unrelated parents, the non-inbred status of offspring is not ‚bothered‘ by the inbreeding coefficient of the parents. Matings of related parent results in offspring which is inbred. In THIS case, the inbreeding status of the parents influences the inbreeding status of the offspring! For instance … A backcross such as F1 x P1 leads to an inbreeding coefficient of this BC1-offspring of F=0.25 ►! if P1 is non-inbred. A backcross such as F1 x P1 leads to an inbreeding coefficient of this BC1-offspring of F=0.50 ►! if P1 is fully inbred.

8. Well, AUTOTETRAPLOIDS have gametes which transfer two alleles per locus. Gametes of homozygous autotetraploid parents can transfer two identical-by-descent alleles. Gametes of autotetra(poly)ploids have thus a „….-zygosity“ status themselves, and they transfer it to offspring!

9. For instance:Parent 1 x Parent 2 aaaa bbbb Offspring aabb What is the inbreeding coefficient F of such offspring individual? F is the probability for two randomly taken alleles to be identical by descent. Here, F=1/3. And there is the coefficient P 2 (defined als probability that there are two pairs of two alleles each, and the two of each pair are ibd) is P 2 = 1. General equation : F (Offpsring) = 1/6 { [F (Parent1) ] + [F (Parent2) ] } P 2 (Offspring) = F (Parent1) x F (Parent2) Fehr, 1987. Principles of Cultivar Development. Vol. 1. Wricke & Weber, 1986. Quantitative Genetics and Selection in Plant Breeding

10. For instance:Parent 1 x Parent 2 aaaa bbbb Offspring aabb What is the inbreeding coefficient F of such offspring individual? F is the probability for two randomly taken alleles to be identical by descent. Here, F=1/3. And there is the coefficient P 2 (defined als probability that there are two pairs of two alleles each, and the two of each pair are ibd) is P 2 = 1. General equation : F (Offpsring) = 1/6 { [F (Parent1) ] + [F (Parent2) ] } P 2 (Offspring) = F (Parent1) x F (Parent2) Fehr, 1987. Principles of Cultivar Development. Vol. 1. Wricke & Weber, 1986. Quantitative Genetics and Selection in Plant Breeding

11. We used to deal with ‚such‘ topics in more details before PCR was invented ….

12. Monoallelic Biallelic Biallelic-duplex Triallellic Quadriallelic

13. Chromosome Segregation! Inbreeding coefficient F after one selfing is only F=1/6 Wricke, Weber, 1986. Textbook on Quantitative Genetics and Selection in Plant Breeding

14. AA x aa F1: Aa 3 : 1 1 : 2 : 1 AAAA x aaaa F1: AAaa Genetic consequences of autotetraploidy: 35 : 1 1 : 8 : 18 : 8 : 1 F2

15. 35 : 1 1 : 8 : 18 : 8 : 1 6 : 24 : 6 = 1 : 4 : 1 A1A2A1A3 A1A4A2A3A2A4 A3A4 A1A2 A1A3 A1A2 A1A4 A1A2 A2A3 A1A2 A2A4 A1A2 A3A4 A1A3 A1A2 A1A3 A1A4 A1A3 A2A3 A1A3 A2A4 A1A3 A3A4 A1A4 A1A2 A1A4 A1A3 A1A4 A2A3 A1A4 A2A4 A1A4 A3A4 A2A3 A1A2 A2A3 A1A3 A2A3 A1A4 A2A3 A2A4 A2A3 A3A4 A2A4 A1A2 A2A4 A1A3 A2A4 A1A4 A2A4 A2A3 A2A4 A3A4 A1A2 A3A4 A1A3 A3A4 A1A4 A3A4 A2A3 A3A4 A2A4 A3A4 There need not be just two alleles per locus ! A1A2 … A1A3 A1A3 A3A4 A1A2 A1A3 … A3A4 A2A4 6 x 24 x

16. Double Reduction Chromatide Segregation

17. Gallais, 1998, 2003: Quantitative genetics and breeding methods in autopolyploid plants. For a given locus, autotetraploid segregation patterns can vary between two extremes: Random Chromosome segretation, Random Chromatid segregation. Under Chromosome Segregation, gametes result from random sampling of 2 chromosomes among 4 homologous chromosomes. The two sister chromatids of a chromosome never assort into the same gamete. Under Chromatid Segregation, gametes results from random sampling of 2 chromatids among 8 homologous chromatides. Two sister chromatids may segregate into the same gamete. This increases homozygosity!

18. Double Reduction is possible and increases homozygosity beyond what is expected in case of chromosome segregation aa AA AA;Aa Diploids

19. Double ReductionNo Cross-over: no double Reduction With cross-over: Double Reduction is possible 1212 3434 aa AA 1234567812345678 1313 2424 Metaphase I Metaphase II Chromatide 1 and chromatide 2 go to DIFFERENT gametes

20. 1414 2323

21. 1212 3434 1414 2323 1 5;6 3 5;6

22. 1212 3434 1 7;8 3 7; 8

23. Double Reduction means that chromatide pieces, distant from centromere, behave „independent“ 1234567812345678 1234567812345678 1234567812345678 Chromosome segregation has a higher probability for loci near to the centromere. Chromatide segregation is higher probable for loci which are distant from centromere, because the probability of cross-over between centromere and such loci is higher. The probability of a double reduction is – in case of pure chromatide segregation – alpha = 1/7. „1/7“ is because a given peace of chromatide has 7 other, homologous pieces vis-à-vis – yet only ONE of those seven is its „Sibling“ with identical-by-descent genes.

24. So this is mainly a warning. Whatever you have learnt on applied genetics, if it comes to autopolyploids, be careful and think twice, thrice – your expertise may mislead you. Facts from population genetics, selection, HWE, segregation, mapping, backcrossing, inbreeding, heterosis, dominance, epistasis, many more … are doubtful if not even wrong. This warinig does not (less) apply to allo-polyploids (B. napus... )