Evoluton of plant sexual diversity

1. WELCOME Dept. of Genetics & Plant Breeding

2. The Evolution of Plant Sexual Diversity MARUTHI PRASAD B. P. PGS19AGR8134 Sr. MSc. (Agri.) Dept. of Genetics & Plant Breeding Dept. of Genetics & Plant Breeding

3. Conclusion 1 5 3 2 • Brief History • Evolutionary Transitions 4 • Strategies promoting Cross Pollination Flow of Seminar • Introduction

4. What is sexual diversity? Dept. of Genetics & Plant Breeding

5. ……But why should you care? • Relevant to many applied areas :Plant breeding and biotechnology, horticulture, conservation and invasion biology • Exhibit greater variety than equivalent reproductive structures of any other group of organisms • Provide outstanding examples of evolution and adaptation, which can be studied in the wild Dept. of Genetics & Plant Breeding

6. Distinctive features of plants that influences their sex lives I don’t have ability to walk to find a partner • Immobility • Hermaphroditism • Immobility and hermaphroditism are highly correlated traits • Hermaphrodites are often immobile even in animals also like corals Dept. of Genetics & Plant Breeding

7. Distinctive features of plants that influences their sex lives • Clonality • Modularity and multiple reproductive structures • Life-history diversity Dept. of Genetics & Plant Breeding

8. How to study plant sex Dept. of Genetics & Plant Breeding

9. Plant sex can also be studied at home in the Darwinian tradition Dept. of Genetics & Plant Breeding

10. Studying plant sex at the DNA level • DNA sequences allow differences between individuals in single nucleotides to be identified • Single nucleotide polymorphism (SNP’s) can be measured for thousand of genes • The consequences of different mating patterns on genetic diversity can be measured and genetic relationships among populations determined Dept. of Genetics & Plant Breeding

11. Plant reproductive modes Reproductive Systems Asexual Sexual Sexual system Dioecious Hermaphrodites Mating system Cross-fertilization Self-fertilization Dept. of Genetics & Plant Breeding

12. Why do reproductive organs of flowers exhibit such astonishing diversity? Dept. of Genetics & Plant Breeding

13. History • Egyptians crossed male and female trees of the date palm to produce fruits. Dept. of Genetics & Plant Breeding

14. The early naturalists began to interpret floral function and make controlled cross and self-pollinations Christian Konrad Sprengel Joseph Koelreuter Thomas Andrew Knight Dept. of Genetics & Plant Breeding

15. Charles Darwin (1809 -1882) • Naturalist, Scientist • Father of Evolution • “On the various contrivances by which British and foreign orchids are fertilised by insects and on the good effects of intercrossing” • “The effects of cross and self fertilization in the vegetable kingdom” • “The different forms of flowers on plants of the same species” Dept. of Genetics & Plant Breeding

16. Charles Darwin’s three books provide the foundations for studies on plant sexual diversity 1862 1876 1877 Dept. of Genetics & Plant Breeding

17. Dept. of Genetics & Plant Breeding

18. Cross pollination Self pollination Dept. of Genetics & Plant Breeding

19. If female and male gametes are produced simultaneously by a plant self fertilization can occur. • Offsprings produced by self fertilization are less fit compare to outcross offsprings. • Because of Inbreeding depression. • Main selective forces that shape the evolution of plant mating strategies. Dept. of Genetics & Plant Breeding

20. Hermaphrodite plants acquire fitness either by being maternal or paternal parents to seeds produced in the next generation. • The maleness or femaleness of the plant, measured as the proportion of a plant’s genes that are transmitted to offspring as a pollen or ovule parent. • Plant gender provides a functional rather than a morphological view of plant sex. Dept. of Genetics & Plant Breeding

21. Strategies promoting cross pollination • Herkogamy • Dichogamy • Self-incompatability • Male sterility Dept. of Genetics & Plant Breeding

22. Sexual polymorphism • Polymorphism: Occurrence of two or more different morphs or forms • Heterostyly • Stigma height dimorphism • Enantoistyly • Flexistyly Dept. of Genetics & Plant Breeding

23. Heterostyly Population is composed of distyly and tristyly Distyly is most common type Long styled called pin type Short styled called thrum type Heteromorphic incompatability system that prevents selfing and intramorph mating Controlled by supergene Dept. of Genetics & Plant Breeding

24. Heterostyly originated in 28 diverse animal-pollinated families Primulaceae Linaceae Lythraceae Erythroxylaceae Turneraceae Iridaceae Dept. of Genetics & Plant Breeding

25. Function of heterostyly ? • “I do not think anything in my scientific life has given me so much satisfaction as making out the meaning of the structure of heterostylous flowers” • Darwin 1876 Dept. of Genetics & Plant Breeding

26. Why Heterostyly will be having reciprocal sex organ ? Dept. of Genetics & Plant Breeding

27. Stigma height dimorphism • Characterized by the presence of two morphs in the population differing only in style heights. • Some individuals present flowers with stigmas positioned above anthers (L-morph), while others have stigmas below anthers (S-morph) • Boraginaceae, Linaceae, Primulaceae and Rubiaceae Dept. of Genetics & Plant Breeding

28. Enantiostyly Mirror image flowers in which style bends either to the left side or right side of the floral axis. Types • Monomorphic enantiostyly • Dimorphic enantiostyly • Monomorphic enantiostyly is common in monocotyledons and dicotyledons • Dimorphic enantiostyly is observed in three monocotyledon families • Haemodoraceae, Tecophilaeaceae, Pontederiaceae Barret, 2002 Dept. of Genetics & Plant Breeding

29. Solanum rostratum Barret, 2002 Dept. of Genetics & Plant Breeding

30. To investigate whether enantiostyly is genetically determined • controlled crosses on Heteranthera multiflora Dept. of Genetics & Plant Breeding

31. Dept. of Genetics & Plant Breeding

32. Flexistyly • Recently been reported from the Zingiberaceae • It combines reciprocal herkogamy and dichogamy in a single floral strategy • Hyperflexistylous morph • Cataflexistylous morph • Flexistyly is reported from at least three clades and 24 species in Alpinia, Amomum and Etlingera Dept. of Genetics & Plant Breeding

33. Alpinia Dept. of Genetics & Plant Breeding Barret, 2002

34. MAJOR EVOLUTIONARY TRANSITIONS EVOLUTIONARY TRANSITIONS: Dept. of Genetics & Plant Breeding

35. EVOLUTIONARY TRANSITIONS • The evolution of selfing from outcrossing • The evolution of separate sexes • The evolution of wind pollination from animal pollination Dept. of Genetics & Plant Breeding

36. The evolution of selfing from outcrossing Why selfing evolves? • Scarce of pollinators • Genetic transmission advantage Dept. of Genetics & Plant Breeding

37. Reproductive assurance • Selfing population occupy range margins • Ecological marginal sites with reduced pollinator densities where outcrosses are absent. Dept. of Genetics & Plant Breeding

38. Automatic selection Self pollination is mediated by pollen vectors and the mating system modifier experiences a transmission bias through the pollen that lead to its selection. Dept. of Genetics & Plant Breeding

39. How selfing is evolved • Replacement of Self incompatible heterostyles with self compatible homostyles with anther and stigma in close contact Dept. of Genetics & Plant Breeding

40. Evolutionary breakdown of distyly in Turnera • Neotropical bee pollinated herb Results: Barret, 1989 Dept. of Genetics & Plant Breeding

41. Evolutionary breakdown of tristyly in Eichhornia • Neotropical bee pollinated herb Barret et al. (2009) Dept. of Genetics & Plant Breeding

42. Evolutionary pathways to self fertilization in a tristylous plant species Eichhorniapaniculata Barret et al . (2009) Dept. of Genetics & Plant Breeding

43. Bakers Law Baker’s law refers to the tendency for species that establish on islands by long-distance dispersal to show an increased capacity for self-fertilization because of the advantage of self-compatibility Dept. of Genetics & Plant Breeding

44. enrichment of self-fertility in species that established on islands following long-distance dispersal • Single individual is sufficient to start a new population • Pannell et al.,2015 Dept. of Genetics & Plant Breeding

45. The evolution of separate sexes • 10% of flowering plants have unisexual flowers. • This condition is called Dicliny • Two categories of Gender variation is recognized, • Gender monomorphism • Gender dimorphism Dept. of Genetics & Plant Breeding

46. Sagittarialatifolia Dept. of Genetics & Plant Breeding

47. The evolution of separate sexes Dept. of Genetics & Plant Breeding

48. Evolutionary pathway Evolutionary pathway Dept. of Genetics & Plant Breeding

49. Disruptive selection Male sterility mutations Genetic modifiers of female fertility gradually convert hermaphrodite to males Sterilitymuatation Recessive mutation of female able to produce pollen e Dept. of Genetics & Plant Breeding Barret, 2002

50. Selective mechanisms • The theory of nuclear inheritance of male sterility indicates that females can spread in ancestral cosexual populations if the product of the hermaphrodite selfing rate (r) and inbreeding depression (δ) exceeds 0.5. • Polyploidy disrupt the functions of self incompatability, resulting in selfing and inbreeding depression. • In Lythium and Lycium this mechanism has been observed Dept. of Genetics & Plant Breeding