Introduction to Plant Development

1. Introduction to Plant Development Keep a green tree in your heart and perhaps the singing bird will come. ...Chinese proverb

2. Genetics Agriculture Ecology Evolution Systematics Basic Biology Pharmaceuticals Molecular Cellular Biology Biotechnology Plant Biology and Related Fields Plant Biology

3. Already • What are the major organ systems that make up the plant body? • what are the major functions of these organs? • What are the three major tissues that make up plant organs? • which cell types comprise these tissues? • what are some functions of these cells? • What cellular structures or cellular processes are unique to plants (or at least highly unusual compared with animals)?

4. Today and Monday • How do plant organs, tissues and cells develop? • Examine Plant Growth, • the irreversible increase in size that (in plants) almost always results from both cell division and cell enlargement, • Examine Plant Cell Differentiation, • the process by which a cell acquires metabolic, structural and functional properties distinct from those of its progenitor, • Development, • the sum total of events that contribute to the progressive elaboration of the body of an organism.

5. Developmental Programs • Indeterminate growth/development, • capacity for g/d over an extended period of time, • vegetative growth and flowering, • g/d is not genetically limited and can* continue as long as environmental conditions and resources permit. • Determinate growth/development • g/d is genetically limited. Plants display great phenotypic plasticity due to a life-style of indeterminate growth and development. *plants have genetically limited life spans.

6. (Toti)potency …the potential of a single cell to become a progenitor for an entire organism (organ, tissue, or cell type), • growth and development are genetically and epigenetically controlled in all organisms, • epigenetics: DNA methylation, chromatin remodeling, etc. • in contrast with most animals, plants retain the capacity to initiate developmental programs throughout their lives, • nucleated plant cells are (all) totipotent.

7. animal development plant development Zygote ---> Several Div. Blastocyst pluripotent totipotent multipotent initials initials initials derivatives derivatives Stem Cells initials …all nucleated plant cells are totipotent.

8. Arabidopsis Zygote (4h) Apical-Basal Axial Development Embryogenesis See fig. 23.5

9. Meristems... …persistent populations of small isodiametric cells with embryonic characteristics.

10. Apical Meristems Shoot Apical Meristem (SAM) • cells that remain in the meristem are termed initials, • cells that are displaced from the meristem and later differentiate, are called derivatives. Root Apical Meristem (RAM)

11. plant development initials initials initials derivatives derivatives Totipotency initials …all nucleated plant cells are totipotent.

12. Primary Meristems • Derive from apical meristems and produce primary growth (apical-basal), • Protoderm: dermal meristem, • Procambium: vascular meristem, • Ground meristem.

13. Plasmodesmata Plant Cell Division

14. Plant Structure Apoplast / Symplast Apoplast The cell wall continuum of a plant. “Outside of the symplast.” Symplast The interconnected protoplasts and their plasmodesmata.

15. SAMShoot Apical Meristem Distal: away from the point of reference, Proximal: situated near the point of reference (the main body), Central/Peripheral: “girth”, also termed lateral, Adaxial/Abaxial: ad (toward), ab (away).

16. Tunica / Corpus

17. Tunica Corpus Tunica / Corpus

18. Primary Meristems SAMShoot Apical Meristem

19. Study this one, and look at lab examples.

20. Leaf Development • Tunica cells differentiate into a leaf founder cell, • divide more rapidly and form the leaf primordium, a meristem with determinategrowth, • Sub-organ domains develop, i.e. upper leaf, lower leaf, mesophyll, vasculature, etc. • L1 (epidermis), L2 (ground tissue) and L3 (vasculature).

21. Phyllotaxy • The number and order in which leaf primordia form is genetically determined and is generally characteristic of species.

22. Study this slide. Review in lab. Ask questions? stomata stomata Leaf Anatomy

23. Developmental Plasticity I Sun Leaf Thermopsis montana Shade Leaf

24. Developmental Plasticity II

25. Mucilage Sloughing off Primary Root Morphology Fig. 36.17

26. Root Morphology The Zone of Elongation Cells Grow in Size Vacuole Appears and Grows Mature Organelles are Produced The Zone of Mitosis (Meristematic) Makes new cells by Mitosis Meristematic Cells Divide by Mitosis The Root Cap To reduce friction from growth in soil The root cap secretes mucilage The root cap sloughs cells

27. See Fig. 36.17 RAMRoot Apical Meristem

28. RAMRoot Apical Meristem …produces new cells proximally and distally.

29. More Root Morphology • Endodermis: • ...innermost layer of the cortex. Casparian Strip: …suberin (fatty) band around the endodermis. Stele: …central cylinder within roots and stems of dicots.

30. Lateral roots form primary meristems in mature regions of roots, • form new roots (organs). Primary Root Morphology

31. Pericycle …outermost layer of the stele in roots, the source of nascent meristematic cells that gives rise to lateral roots, • …root primordia form, • …protoderm, ground meristem and procambium form, • …root cap forms, pushes through the cortex, • …vasculature forms between stele and differentiating derivatives of the root primordium.

32. Meristemsknow them Monday: lateral meristems (2o growth).

33. apical/basal, axial SAM embryogenesis RAM primary growth Leaf Primordia ? ? ? Stem Tissues 2o Growth ? primary growth Structure/Function 2o Growth ? Patterns of Development Cotyledons Hypocotyl Root Zygote Embryo SAM Cell Differentiation 1o Growth RAM Root Tissues 1o Growth

34. Monday • Read the rest of the chapter, • Stump the me with questions?