Wikipedia talk:WikiProject Plant Evo Devo

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Contents

[edit] Name of the main page and the first material to go on the page

"Plant evo devo" seems to be a little short, but is a good title in the practical sense. Plant evolutionary development//Plant evolutionary developmental biology//Evolution of plant development are not titles someone would search. The following should go on the page first:

1) Introduction

-- What is evo devo

-- How has the field as a whole progressed in the past few years: Animal evo devo, Model systems

-- Why is it relevant to plants: Plant shape, size, early evolution

-- What is the current state of plant evo devo research

Max 8-10 lines

2) Image showing diversity in plant form

3) Something saying that the project is under development

Anything else??

Gauravm1312 03:30, 4 October 2007 (UTC)

[edit] Task2: Historical development of the field

Things to be taken into consideration

[edit] Pre 1900

  • Johann Wolfgang von Goethe, 1790

Metamorphosis of Plants (originally published as Versuch die Metamorphose der Pflanzen zu erklären)

[edit] 1900-Current

F. Laibach first summarized the potential of Arabidopsis thaliana as a model organism for genetics in 1943 - he did some work on it much earlier though, publishing its correct chromosome number in 1907. The first collection of induced mutants was made by Laibach's student E. Reinholz. Her thesis was submitted in 1945, the work published in 1947.

  • Katherine Esau (the mid 1900s) The Katherine Esau Award is awarded to the graduate student who presents the best paper in structural and developmental biology at the annual meeting of the Botanical Society of America. Known for her book, the bible of plant development titled Plant Anatomy. Worked with Cheadle on evolutionary specialization of the phloem tissue wrt function, using fossil records and comparative anatomy.
  • The early part of the century focussed more on macroscopic developmental parameters, the origins and growth of tissues and organs, microscopic observations etc, while after the discovery of the DNA and molbio techniques, things started to get more molecular.
  • Tools of the Genomic era:

-- T-DNA lines, Complementation, Physical map, Genetic map, Transposon Tagging, rapid transformation protocols, RNAi vectors for Arabidopsis

-- Burgeoning ESTand genome sequence data for non-model organisms

-- Comparative gene expression analyses -- Bioinformatics tools


-- Other information to source from other pages...please add...

Images to include: 1) Either from old papers // Classical thinkers, if any

Length: Should not be more than 20 lines (arbitrary decision)

Gauravm1312 18:04, 4 October 2007 (UTC)

[edit] Organisms, Databases and Tools

-- It should be stressed that although evo devo looks more at non-model species, the information derived from model organisms forms the basis on which this comparison is done. Model organisms for devo studies:

  1. Arabidopsis thaliana -- ABC floral model, rapid life cycle, selfing
  2. Maize -- transposons; gene dosage effects
  3. Physcomitrella patens -- Haploid, clonal populations, simple anatomy

Prime Non-model organisms:

  1. Brassica -- Why? Suitable position in phylogenetic tree (Mustard family)
  2. Rice -- Hormonal influences (GA)
  3. Antirrhinum majus - Leaf architecture
  4. Tobacco -- Tobacco mosaic virus


-- What all we know related to development in Arabidopsis and Antirrhinum and through other plants like rice, maize etc

   -- ABC Model
   -- Hormonal influences
   -- Leaf growth and patterning
   -- Meristem growth and differentiation
   -- Genetic networks involved in various physiological processes, genome sequence, EST
   -- Microarray expression data


  • Information from non-model species

-- Phylogeny, Comparative phylogenetics, Cross-species expression analysis, Bioinformatics tools for sequence analyses


  • EST databases and Genome sequence databases and information obtained from them. How this information is affecting evo devo research. General overview of this.

Gauravm1312 22:42, 6 October 2007 (UTC)

[edit] Tidbits for future writes

[edit] Meristem identity

  • In meristem genetic screens, CLV mutation does not create much problems in the initial stages of meristem development. But as the plant growth progresses, the patterns start emerging. For eg, in the inflorescence meristem, the floral primordia r generated in high numbers. In floral meristem, higher number of lateral organs, for eg: 12 carpels. One of the factors controlling floral organ number is simply the number of cells available for primordia. So the extra stem cells produced differentiate in accordance with the normal developmental program.

In maize, a mutation called FASCIATED EAR2 confers defects in shoot meristems roughly equivalent to that seen in clv Arabidopsis plants. This gene was cloned and found to be closely related to CLV2, suggesting that this mechanism of stem cell number regulation is evolutionarily conserved.


  • In plants LRR-RLKs are very evolutionarily popular, and appear in other proteins such as BRI1, which participates in the BRASSINOLIDE RECEPTOR BRI1, and ERECTA, which controls cell elongation. There are at least 200 other LRR-RLKs of unknown function, still.
  • A recent discovery suggests that there are many proteins in plants that have homology to the CLV3 protein; in Arabidopsis about 30. This is especially in a small domain called the CLE domain; in CLV3 this is the domain that contains the active 12-amino acid peptide. In fact, many of these proteins can substitute for CLV3 when expressed to sufficient levels in the meristem.
  • ARGONAUTE1(AGO1) and ZWILLE are genes involved in meristem differentiation that belong to the evolutionarily conserved family of AGO-like proteins involved in RNA mediated gene silencing. Their homologs, in animals atleast, are part of the RISC complex.

Plant Molecular Biology. Special Issue on meristem development

  • How did meristem evolve from earliest plant to current plants? —Preceding unsigned comment added by 35.11.48.243 (talk) 04:09, 26 October 2007 (UTC)
  • What happens in tall plants? How is their meristem different from normal plants?
  • Phenotypic difference between SAM of different plants
  • Meristem ---> Primordium of different types. Is there a conserved pattern?

Gauravm1312 18:49, 14 October 2007 (UTC)

[edit] Leaf Patterning

  • Phyllotaxy can be discussed evolutionarily. Change in expression of only one gene ABNORMAL PHYLLOTAXY causes change from distichous (alternate) phyllotactic program to decussate (arranged in pairs). Evolution of this gene studied?? Phyllotaxy can change during plant development. However the floral meristem produces organs in a whorled phyllotaxy. This is essential from an evolutionary view, because the various phyllotaxies of leaves permit maximal light harvesting, ie because the leaves are not so shaded by those above, whereas the whorled petals provide enhanced visual impact for pollinators, and the whorling of stamens and carpels is essential for the mechanisms of pollination and fertilization.
  • Evolution of class III HD-ZIP gene family in land plants
  • ARGONAUTE (ago) family of genes is conserved from yeast to plants to animals. miRNA.
  • Leaves serve as the main photosynthetic organs in plants. They develop from the SAM, through the leaf primordial cells, and at maturity, are mostly determinate. We see a huge diversity in plant leaf morphologies.
  • How is the variation in leaf shape and size generated?

Gauravm1312 00:42, 20 October 2007 (UTC)

[edit] miRNAs

  • ROLLED LEAF from maize has sequence similarity to REV, but functional similarity to PHV/PHB genes. Its expression is regulated by miRNA. It is necessary for the determination of the adaxial leaf surface. The significance of this gene lies in the fact that the miRNAs that control its expression are conserved from Arabidopsis to Maize. It underlines the important role of these miRNAs in evolution of the palnt form.

Gauravm1312 20:43, 21 October 2007 (UTC)

[edit] Vasculature

  • Not all plants are vascular. Evolution of vasculature has allowed plants to reach a much greater height

Gauravm1312 17:13, 24 October 2007 (UTC)

[edit] Flowering Time

  • The example of CO from Arabidopsis and Hd1 from rice. Rice flowers early in short days, as against Arabidopsis, which is a long day plant. Genetic analysis reveals that the players in this pathway are ALL THE SAME. But in Arabidopsis, CO, the junction regulator enhances FT expression, which is a Flowering Time gene, while in Rice, CO's homolog Hd1 represses Hd3a, which is a FT homolog. This results in opposite regulation of downstream pathways. The circadian rhythmicity is entrained to a ~24 hour cycle by light and CO expression has this ~24 hour rhythmicity.

It has been recently reported that the Hd1 orthologue from the long-day grass, wheat, can complement Hd1-deficient rice.(29) Similarly, a CO gene from a short-day plant Pharbitis nil can complement the Arabidopsis co mutation.

  • Another example is the intra-specific difference between various Arabidopsis ecotypes. While winter-annuals flower only after a prlonged period of vernalization, ecotypes from warmer regions and also common lab strains flower without this requirement. This has been found to be because of the variations in two critical flowering time genes FLC and FRIGIDA (FRI), atleast FLC being mutated in the summer-annuals.

Ref: Its time to flower: the genetic regulation fo flowering time

  • Natural variation in flowering time. What all do we know at the genetic level?

-- FT and FLC loci variation as mentioned above

-- Domestication of maize and barley Barley has a winter type, and requires sowing before winter. All have reduced response to photoinduction, all are low LD plants. Allelic difference at one locus reuslts in CONSTANTANS misexpression resulting in altered FT.

Gauravm1312 22:59, 4 November 2007 (UTC)

[edit] FLoral meristem

  • ap1/cal double mutants generate a cauliflower like inflorescence, wherein the floral meristem retains its vegetative identity to some extent. Turns out in cauliflower (Brassica oleraceae var botrytis), the CAL gene is mutated and not expressed.

Gauravm1312 05:19, 14 November 2007 (UTC)


[edit] Parallels between animal and plant evolution

1) homeotic genes - Hox genes, MADS Box. relate that to segmental patterns in drosophila and floral domains in plants

2) polycomb genes repress homeotic genes in later phases of development

3) mechanisms of evolution more or less remain similar

4) morphogen gradients - Drosophila embryonic development, wing development, leaf development, flower development. examples of morphogen gradients

5) Epigenetic mechanisms exist - vernalization, repression of homeotic genes

Gauravm1312 (talk) 20:27, 24 November 2007 (UTC)