Week 2
Lecture 5 – Auxin transport (TK) 31
Lecture 6 – Cell wall (TK) 45
Lecture 7 – Cell polarity and polar growth (TK) 60
Lecture 8 – Introduction, environmental control of shoot development (CT) 69
Week 3
Lecture 9 – Plasticity of root development (CT) 72
Lecture 10 – Root dynamics & hydrotropism (CT) 78
Lecture 11 – Shoot Apical Meristem (SAM) & Leaf Development (RI 81
Lecture 12 – Physics in morphogenesis I (TK) 90
Week 4
Lecture 13 – Paper: Developmental Patterning by Mechanical Signals in Arabidopsis (TK) 98
Lecture 14 – Thermomorphogenesis (CT and guest Scott Hayes) 101
Week 5
Computer case 1 – Flower initiation (RI) 104
Lecture 15 – Shade avoidance (CT and guest Ronald Pierik) 123
Week 6
Computer case 2 – ABC model (RI) 128
Lecture 16 – Evolution of root nodule formation (RI) 139
Lecture 17 – Evolutionary developmental biology: LEAFY (RI) 145
,Lecture 1 – General introduction
Learning goals
• Concepts in plant development & plant developmental regulation (molecular, cellular
physiological levels)
• Environmental cues directing plant development
• Evolution of developmental regulation
→ 17 different topics
From unicellular to multicellular
New (visible) characteristics in Volvox carteri:
• 2000 cells, two cell types
• Massive complex extracellular matrix
• Asymmetric cell division
• Egg/sperm sexual program
Comparing the genomes: very little difference in genome size/gene numbers?
What are the differences?
• Only 32 ‘EST-supported’ Volvox gene models lack detectable homologs in Chlamydomonas,
suggesting that limited protein-coding innovation occurred in the Volvox lineage
• Volvox specific expansion compared to Chlamydomonas: matrix metalloproteases
(degradation of extracellular matrix proteins) & leucine-rich repeat proteins (cell-membrane-
located-receptors)
• ‘Glueing single cells together and start communication’ (cell specification became dominant
later during evolution)
What did we learn?
How can gene functions evolve?
• Through minor rewiring of existing genetic circuits
• Via (large-scale) gene amplifications and diversifications
How to study this?
• Comparative genomics!
2
,Old, new and ‘split’ functions
• Nonfunctionalization: the production of a pseudogene from a functional gene due to a
mutation event; often the result of single gene duplications.
• Neofunctionalization: one copy retains its ancestral functions, and the other acquires a
novel function, adaptive mutation process; one of the gene copies must mutate to develop
this novel function.
• Subfunctionalization: neutral mutation process; no new adaptations are formed. During the
process of gene duplication, paralogs undergo a division of labor by retaining different parts
(subfunctions) of their orginial ancestral function.
Plants vs animals – summary
• Diverged 1.6 billion years ago
• Last common ancestor was a unicellular eukaryote
• Multicellular organisms evolved independently
• Basic repertoire of regulatory proteins is similar in plant and animals, though have diverged
differently
What determines the developmental strategies of plants?
• They can’t move = sessile organisms
• Interaction with the environment is very important
Basic repertoire of regulatory proteins
Signals
• Intrinsic signals: like hormones (T2, T5, T9), metabolites and mechanical forces (T7, T12, T13)
• External signals: like light and temperature (abiotic; T8, T10), predators and symbionts
(biotic; T16)
3
, Plant hormones
→ Small organic compounds that can cross the cell wall, e.g.:
• Gibberellic acid (GA3) – a gibberellin
• Zeatin – a cytokine
• Indole-3-acetic acid (AA) – an auxin
• Brassinolide – a brassinosteriod
• Abscisic acid (ABA)
• Ethylene
Plant receptors
Type of receptor C. elegans (worm) Arabidopsis (plant)
Nuclear hormone receptors 270 1? (L2)
(LRR) ser/thr receptor kinases - >100 (L11)
Receptor tyrosine kinases Large number -
Histidine kinase 2 component - >8
receptors
G-protein-linked receptors >1000 1?
4
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller lyrasoeterbroek. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $5.86. You're not tied to anything after your purchase.