Thursday Lecture – Legumes

1. Thursday Lecture – Legumes Reading: Textbook, Chapter 6

2. Optional Assignment - Due Tuesday March 1 Where do “baby carrots” come from? - How are they produced? [is there such a thing as a pregnant mama-carrot?!]

3. Quiz

4. Quiz • What is a legume? • List two crop plants that are members of the legume family

5. Fabaceae

6. Fabaceae = Leguminosae Legume family (also called bean family or pea family)

7. Fabaceae = Leguminosae Legume family (also called bean family or pea family) “legere” – Latin for “too gather”

8. Fabaceae = Leguminosae Legume family (also called bean family or pea family) “legere” – Latin for “too gather” 19,000+ species – 3d largest

9. Fabaceae = Leguminosae Legume family (also called bean family or pea family) “legere” – Latin for “too gather” 19,000+ species – 3d largest 41 crop species – most of any family

10. Fabaceae = Leguminosae Legume family (also called bean family or pea family) “legere” – Latin for “too gather” 19,000+ species – 3d largest 41 crop species – most of any family Cereal + Legume  complete protein

11. Legume – Papilionoid flower See Fig. 6.1, 6.2, page 138

12. Legume – Papilionoid flower See Fig. 6.1, 6.2, page 138 Banner petal

13. Legume – Papilionoid flower See Fig. 6.1, 6.2, page 138 Banner petal wing

14. Legume – Papilionoid flower See Fig. 6.1, 6.2, page 138 Banner petal wing keel

15. Legume – Papilionoid flower See Fig. 6.1, 6.2, page 138 Banner petal wing keel Stamens: 9 + 1

16. Papilionoid legumes

17. Papilionoid legumes

18. See Fig. 6.1, page 137 Other Legumes Acacia - Mimosoideae

19. See Fig. 6.1, page 137 Other Legumes Acacia - Mimosoideae Senna - Caesalpinoideae

20. Nitrogen Fixation Paradox – atmosphere is 80% nitrogen (N) yet N is a limiting factor for plant growth in almost all ecosystems

21. Nitrogen Fixation Paradox – atmosphere is 80% nitrogen (N) yet N is a limiting factor for plant growth in almost all ecosystems Resolution – atmospheric nitrogen is in a form (N2) that is not available for chemical reactions in biological organisms

22. Nitrogen Fixation Paradox – atmosphere is 80% nitrogen (N) yet N is a limiting factor for plant growth in almost all ecosystems Resolution – atmospheric nitrogen is in a form (N2) that is not available for chemical reactions in biological organisms How does nitrogen become available to living organisms?

23. Nitrogen Fixation • Paradox – atmosphere is 80% nitrogen (N) yet N is a limiting factor for plant growth in almost all ecosystems • Resolution – atmospheric nitrogen is in a form (N2) that is not available for chemical reactions in biological organisms • How does nitrogen become available to living organisms? • reaction is called “fixation”

24. Nitrogen Fixation • Paradox – atmosphere is 80% nitrogen (N) yet N is a limiting factor for plant growth in almost all ecosystems • Resolution – atmospheric nitrogen is in a form (N2) that is not available for chemical reactions in biological organisms • How does nitrogen become available to living organisms? • reaction is called “fixation” • can occur with input of energy (lightning strike)

25. Nitrogen Fixation • Paradox – atmosphere is 80% nitrogen (N) yet N is a limiting factor for plant growth in almost all ecosystems • Resolution – atmospheric nitrogen is in a form (N2) that is not available for chemical reactions in biological organisms • How does nitrogen become available to living organisms? • reaction is called “fixation” • can occur with input of energy (lightning strike) • some microorganisms can carry out this reaction

26. Nitrogen Fixation • Paradox – atmosphere is 80% nitrogen (N) yet N is a limiting factor for plant growth in almost all ecosystems • Resolution – atmospheric nitrogen is in a form (N2) that is not available for chemical reactions in biological organisms • How does nitrogen become available to living organisms? • reaction is called “fixation” • can occur with input of energy (lightning strike) • some microorganisms can carry out this reaction • mutualism between bacteria (Rhizobium etc.) and members of Fabaceae

27. Nitrogen-fixing Root Nodules N2 Fixing Nodules

28. Nitrogen-fixing Root Nodules N2 Fixing Nodules Bacteria in cells

29. Can we transfer N-fixation to other crops? See Box 6.1, page 141

30. Can we transfer N-fixation to other crops? • See Box 6.1, page 141 • Morphological changes – development of nodule

31. Can we transfer N-fixation to other crops? • See Box 6.1, page 141 • Morphological changes – development of nodule • - critically important because need to exclude O2

32. Can we transfer N-fixation to other crops? • See Box 6.1, page 141 • Morphological changes – development of nodule • - critically important because need to exclude O2 • Host/symbiont recognition

33. Can we transfer N-fixation to other crops? • See Box 6.1, page 141 • Morphological changes – development of nodule • - critically important because need to exclude O2 • Host/symbiont recognition • Chemical reactions to carry out N2 fixation

34. Can we transfer N-fixation to other crops? • See Box 6.1, page 141 • Morphological changes – development of nodule • - critically important because need to exclude O2 • Host/symbiont recognition • Chemical reactions to carry out N2 fixation •  Multiple genes, multiple chromosome locations, not trivial

35. Nitrogen Cycle See Fig. 6.4, page 140 1. nitrogen fixation 2. ammonification 3. nitrification atmospheric fixation 4. denitrification ammonification nitrogen fixing bacteria nitrification denitrifying bacteria

36. Nutritional Aspects of Legumes See Box 6.2, page 142 • Legumes produce many N-containing compounds • - nutritious foods (proteins, vitamins)

37. Nutritional Aspects of Legumes See Box 6.2, page 142 • Legumes produce many N-containing compounds • - nutritious foods (proteins, vitamins) • - poisons (alkaloids, cyanogens)

38. Nutritional Aspects of Legumes See Box 6.2, page 142 • Legumes produce many N-containing compounds • - nutritious foods (proteins, vitamins) • - poisons (alkaloids, cyanogens) • Amino acid content of proteins – complements grains

39. Nutritional Aspects of Legumes See Box 6.2, page 142 • Legumes produce many N-containing compounds • - nutritious foods (proteins, vitamins) • - poisons (alkaloids, cyanogens) • Amino acid content of proteins – complements grains • High fiber levels

40. Nutritional Aspects of Legumes See Box 6.2, page 142 • Legumes produce many N-containing compounds • - nutritious foods (proteins, vitamins) • - poisons (alkaloids, cyanogens) • Amino acid content of proteins – complements grains • High fiber levels • Isoflavones – appear to lower cholesterol levels

41. Nutritional Aspects of Legumes See Box 6.2, page 142 • Legumes produce many N-containing compounds • - nutritious foods (proteins, vitamins) • - poisons (alkaloids, cyanogens) • Amino acid content of proteins – complements grains • High fiber levels • Isoflavones – appear to lower cholesterol levels • Phytoestrogens  may help relieve menopause symptoms

42. Nutritional Aspects of Legumes See Box 6.2, page 142 • Legumes produce many N-containing compounds • - nutritious foods (proteins, vitamins) • - poisons (alkaloids, cyanogens) • Amino acid content of proteins – complements grains • High fiber levels • Isoflavones – appear to lower cholesterol levels • Phytoestrogens  may help relieve menopause symptoms • Oligosaccharides (beans, beans, the musical fruit … - see Box 6.3, page 150)

43. A Poisonous Legume Abrus precatorius – Precatory Bean Abrin – toxin, one of most toxic substances known 1 crushed seed can be fatal if ingested

44. Legumes – Changes Under Domestication • Annual habit, selfing breeding system

45. Legumes – Changes Under Domestication • Annual habit, selfing breeding system • Less seed scattering

46. Legumes – Changes Under Domestication • Annual habit, selfing breeding system • Less seed scattering • Greater seed size

47. Legumes – Changes Under Domestication • Annual habit, selfing breeding system • Less seed scattering • Greater seed size • Synchronous fruiting

48. Legumes – Changes Under Domestication • Annual habit, selfing breeding system • Less seed scattering • Greater seed size • Synchronous fruiting • Loss of dormancy

49. Legumes – Changes Under Domestication • Annual habit, selfing breeding system • Less seed scattering • Greater seed size • Synchronous fruiting • Loss of dormancy • - question: which came first, domestication or loss of dormancy?

50. Legumes – Changes Under Domestication • Annual habit, selfing breeding system • Less seed scattering • Greater seed size • Synchronous fruiting • Loss of dormancy • - question: which came first, domestication or loss of dormancy? • Recent studies – no common set of “domesticated genes”