Αναπτυξιακή Βιολογία Φυτών ΒΙΟΛ 447

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1 Αναπτυξιακή Βιολογία Φυτών ΒΙΟΛ 447 Μάθημα Επιλογής και των δύο κατευθύνσεων Διδάσκων: Κρίτων Καλαντίδης

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4 Εισαγωγή: Τι θα διδαχθεί* Oι βασικοί όροι, η φυτική βιολογία, τα επιστημονικά της πεδία Οργανισμοί μοντέλα Μεθοδολογία Γενετική Μοριακές Τεχνικές Βιοχημεία *εκτός απροόπτου

5 Τι θα διδαχθεί* Πρωτογενής και δευτερογενής ανάπτυξη Συντονισμός της ανάπτυξης στα φυτά Ο ρόλος των φυτο-ορμονών στην ανάπτυξη Ενδογενής και εξωγενής πληροφορία *εκτός απροόπτου

6 Τι θα διδαχθεί* Εμβρυογένεση Οι φυτικοί βλαστικοί ιστοί Το ακραίο μερίστωμα *εκτός απροόπτου

7 Τι θα διδαχθεί* Ανάπτυξη του φύλλου Βασικές αρχές Γονίδια που εμπλέκονται Ανάπτυξη του άνθους Βασικές αρχές Το μοντέλο ABC Ανάπτυξη της ρίζας Ανατομία της ρίζας Μοριακή Γενετική της ανάπτυξης της ρίζας *εκτός απροόπτου

8 Βασικοί όροι Διαφοροποίηση Μορφογένεση Αύξηση

9 Τι είναι αυτό που λέμε ανάπτυξη; Development: The coordinated sequence of cell divisions, growth, and differentiations leading to the formation of new organs and tissues (wikipedia) Η συντονισμένη αλληλουχία κυταρικών διαιρέσεων, αύξησης και διαφοροποίησης που έχει ως συνέπεια την δημιουργία νέων οργάνων και ιστών

10 Τα φυτά παρουσιάζουν εκπληκτική ποικιλομορφία, στο μέγεθος, στο χρόνο ζωής και φυσικά και στις αναπτυξιακές τους στρατηγικές Ορατό μόνο με μικροσκόπιο ζεί λίγες μέρες ~20εκ Ζεί λίγες εβδομάδες Δεκάδες μέτρα, ζεί δεκάδες χρόνια

11 Sequoia sempervirens (Lamb. ex D. Don) Endl. - redwood Πολλές δεκάδες μέτρα, ζει αιώνια

12 Οι αρχαιότεροι οργανισμοί στον πλανήτη Pinus longaeva

13 Pinus longaeva : Περιορισμένη εξάπλωση αλλά και περιορισμένοι κίνδυνοι

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15 Ποια είναι η σχέση μεταξύ μεγέθους γονιδιώματος και πολυπλοκότητας ενός οργανισμού;

16 Ποια είναι η σχέση μεταξύ μεγέθους γονιδιώματος και πολυπλοκότητας ενός οργανισμού;

17 Πόσα γονίδια έχει το ανθρώπινο γονιδίωμα; Στοιχήματα στο GeneSweep την άνοιξη του 2000 Με βάση τον ρυθμό των μεταλλάξεων, ο μέγιστος αριθμός των αναγκαίων γονιδίων είναι συγκεκριμένος και περιορισμένος (~40.000)

18 Sandwalk.blogspot.com Facts and Myths Concerning the Historical Estimates of the Number of Genes in the Human Genome Larry Moran is a Professor in the Department of Biochemistry at the University of Toronto. You can contact him by at "sandwalk (at) bioinfo.med.utoronto.ca".

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21 Wikipedia Selecting a model organism Models are those organisms with a wealth of biological data that make them attractive to study as examples for other species including humans that are more difficult to study directly. These can be classed as genetic models (with short generation times, such as the fruitfly and nematode worm), experimental models, and genomic models, with a pivotal position in the evolutionary tree [2]. Historically, model organisms include a handful of species with extensive genomic research data, such as the NIH model organisms.[3]

22 Οργανισμοί μοντέλα του NIH

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24 Selecting a model organism Wikipedia Often, model organisms are chosen on the basis that they are amenable to experimental manipulation. This usually will include characteristics such as short life-cycle, techniques for genetic manipulation (inbred strains, stem cell lines, and transfection systems) and non-specialist living requirements. Sometimes, the genome arrangement facilitates the sequencing of the model organism's genome, for example, by being very compact or having a low proportion of junk DNA (e.g. yeast, Arabidopsis, or pufferfish). Tetraodon When researchers look for an organism to use in their studies, they look for several traits. Among these are size, generation time, accessibility, manipulation, genetics, conservation of mechanisms, and potential economic benefit. As comparative molecular biology has become more common, some researchers have sought model organisms from a wider assortment of lineages on the tree of life.

25 Petunia hybrida

26 Nicotiana tabacum And BY-2 cells

27 Zea mays

28 Solanum lycopersicon

29 Salicaceae Populus balsamifera ssp. trichocarpa

30 Oryza sativa

31 Chlamydomonas reinhardtii

32 Medicago truncatula Medicago truncatula has been chosen as a model organism for legume biology. It has a small diploid genome, is self-fertile, has a rapid generation time and prolific seed production, and is also amenable to genetic transformation. The genome of M. truncatula is currently being sequenced. It forms symbioses with nitrogen-fixing rhizobia Sinorhizobium meliloti and arbuscular mycorrhizal fungi. The model plant Arabidopsis thaliana does not form either symbiosis, making M. truncatula an important tool for studying these processes.

33 Lotus formosissima

34 Physcomitrella patens

35 Lemna gibba Lemna gibba is a rapidly-growing aquatic monocot, one of the smallest flowering plants. Lemna growth assays are used to evaluate the toxicity of chemicals to plants in ecotoxicology. Because it can be grown in pure culture, microbial action can be excluded. Lemna is being used as a recombinant expression system for economical production of complex biopharmaceuticals. It is also used in education to demonstrate population growth curves.

36 Sorghum bicolor

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43 Διάγραμμα και εικόνα οριζόντιας τομής Άνθους Arabidopsis thaliana

44 2n = 10 The Arabidopsis Karyotype Chromosome μm Chromosome μm NOR Chromosome μm Chromosome μm NOR Chromosome μm

45 Evolutionary distance of Arabidopsis to other plant species Arabidopsis/ Capsella rubella Arabidopsis/ Brassica sp. Arabidopsis/ tomato Arabidopsis/ rice Plants/ Animals Myr Myr 150 Myr 200 Myr 1.6 Byr

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47 Sequencing project statistics Size: 125MBp (sequenced 115) Base composition: ~35% GC content Total number of genes: 25,5 Average gene length: ~1,9kb Density ~50% Exons: Av. Size 250bp, av. Per gene >5 Introns: av.size 165bp, av.per gene 4

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49 Sequencing project statistics 17% of all Arabidopsis are arranged in tandem repeats Unique genes in Arabidopsis 35% two 12.5% three 7% four 4.4% five 3.6% >five 37% 24 large duplicated segments of 100kb comprising 58% of the genome transcription factors are the less conserved category amongst eucaryots, Αναπτυξιακή protein Βιολογία synthesis Φυτών genes most conserved

50 Properties of the Arabidopsis genome The functions of 69% of the genes were classified according to similarity to known function in other orgnisms 48% of known human disease genes have their equivalent in Arabidopsis Transposons account for at least 10% of the genome

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53 Modules derived from meristems

54 Βασικά Σημεία της ανάπτυξης των φυτών Μη μετακίνηση του οργανισμού Μη μετακίνηση των κυτάρων Αποτελούνται από τον κύριο βλαστό, τούς κλώνους και τη ρίζα Η ανάπτυξή τους συμβαίνει σε επαναλαμβανόμενες μορφώματα (υπομονάδες) Η επαναλ. των ίδιων υπομονάδων προσδίδει πλαστικότητα στην ανάπτηξη των φυτών Η φυτικές ορμόνες κατευθύνουν πολλές διαδικασίες ταυτόχρονα

55 Βασικά Σημεία της ανάπτυξης των φυτών Η αναπτυξιακές υπομονάδες είναι προϊόντα της δράσης των φυτικών «βλαστικών» κυτάρων Η φυλλόταξη είναι αποτέλεσμα αλληλεπιδράσεων που συμβαίνουν στα μεριστώματα Τα μεριστώματα έχουν δομική οργάνωση Τα μεριστώματα συντηρούνται ως αποτέλεσμα μοριακών αλληλεπιδράσεων Τα μεριστώματα δημιουργούνται ήδη κατά την ανάπτυξη του εμβρύου

56 Η ανάπτυξη των φυτών χαρακτηρίζεται από αναπτυξιακές υπομονάδες (modules) και είναι συνεχής. Έχει δύο γενικές φάσεις, την αυξητική (vegetative) και την αναπαραγωγική (generative)

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58 Rules for module production plastochron

59 Η ΑΝΑΠΤΥΞΗ ΤΩΝ ΦΥΤΩΝ ΒΑΣΙΖΕΤΑΙ ΣΤΗΝ ΑΞΙΟΠΟΙΗΣΗ ΤΗΣ «ΑΝΑΠΤΥΞΙΑΚΗΣ ΥΠΟΔΟΜΗΣ» ΤΟΥ ΚΥΤΤΑΡΟΥ ΜΕΤΑ ΑΠΟ ΠΕΡΙΒΑΛΟΤΙΚΗ ΣΗΜΑΤΟΔΟΤΗΣΗ H ΑΝΑΠΤΥΞΙΑΚΗ ΥΠΟΔΟΜΗ ΕΙΝΑΙ ΑΠΟΤΕΛΕΣΜΑ ΚΥΤΤΑΡΙΚΗΣ ΚΑΤΑΓΩΓΗΣ ΑΛΛΑ ΚΥΡΙΩΣ ΚΥΤΤΑΡΙΚΗΣ ΘΕΣΗΣ

60 Primary and secondary plasmodesmata have very different size exclusions ranging from 1-20kDa, secondary plasmodesmata have usually smaller size exclusion limit (ca 1 kda)

61 Σηματοδότηση - Signalling Δύο τύποι σημάτων (σινιάλων): ενδογενή και εξωγενή Ενδογενή σήματα: Transcription factors, plant hormones (auxin), mirnas, etc (e.g. sterols)

62 Antirrhinum majus Aclaim images

63 Growth: An irreversible increase in size (length, volume, mass, dry weight). This is a measurable (quantitative) term. Differentiation: A progressive change toward a more specialized (different) state. The process by which cells become specialized (take on specific functions). This process is reversible for most plant cells: dedifferentiation (totipotency). This is a descriptive (qualitative) term. Development: The coordinated sequence of cell divisions, growth, and differentiations leading to the formation of new organs and tissues. The orderly outgrowth of organs and the progression from seed to seedling to vegetative plant to flowering plant. The process by which a fertilized egg becomes a flowering plant. Development is a general ("umbrella") term.

64 History of Arabidopsis thaliana as a research organism. "Arabidopsis thaliana was discovered by Johannes Thal (hence, thaliana) in the Harz mountains in the sixteenth century, though he called it Pilosella siliquosa (and it has gone through a number of name changes since). The earliest report of a mutant (that I know of) was in 1873 (by A. Braun). F. Laibach first summarized the potential of Arabidopsis thaliana as a model organism for genetics in he did some work on it much earlier though, publishing its correct chromosome number in The first collection of induced mutants was made by Laibach's student E. Reinholz. Her thesis was submitted in 1945, the work published in Langridge played an important role in establishing the properties and utility of the organism for laboratory studies in the 1950s, as did Rédei and others (such as J.H. van der Veen in the Netherlands, J. Veleminsky in Czechoslovakia and G. Röbbelen in Germany) in the 1960s. One of Rédei's many important contributions was to write scholarly reviews on Arabidopsis, a particularly thorough one is in Bibliographica Genetica vol 20, No. 2, 1970, pp He wrote a more easily found one in Ann. Rev. Genet. (1975) vol. 9, Both go through some of the early history of the use of Arabidopsis in the laboratory, though the longer 1970 one has all the details." --from Elliot Meyerowitz, 1998

65 Tobacco (Nicotiana tabacum) is one of the most studied high plant species. There are important economic reasons for this, but futhermore tobbaco can be easily transformed and has a relatively short generation time (1, 2, 3). It has been widely used in pathogen response (4, 5, 6, 7), pyridine alkaloid (like nicotine) biosynthesis (8, 9, 10), cell cycle (11, 12, 13, 14), oxidative stress (15, 16) and pollen tube development studies (17, 18). Chromosome number 12 Polyploid 4n (allotetraploid) Estimated genome size Information not available Genome sequencing project The Nicotiana tabacum genome is being sequenced by the Tobacco Genome Initiative (TGI). See Tobacco Genome Initiative (TGI).

66 Common tomato (Solanum lycopersicum) is one of the most popular fleshy fruit in the world. Tomato originated in the New World in the Andean region. The abundant genetic resources, like germplasm or mutants collections, high-density genetic maps (1, 2), efficient transient and stable transformation (3), EST databases (4, 5) and microarrays (6, 7), make tomato an essential model system in the study of fleshy fruits. It is a plant model for analysis of QTL (8, 9), fruit development (10), ripening processes (11, 12, 13), salinity tolerance (14), plant disease (15, 16, 17), carotenoid (18, 19) and cell wall biosynthesis (20, 21,22). Chromosome number 12 Polyploid 2n (mainly) and 4n Estimated genome size 950 Mb Genome sequencing project The Solanum lycopersicum genome is being sequenced by the International Tomato Genome Sequencing Consortium. See International Tomato Genome Sequencing Project.

67 Lemna Assessing the toxicity of chemicals with Lemna OECD[1] and US EPA[2] guidelines describe toxicity testing using Lemna gibba or Lemna minor as test organisms. Both of these species have been studied extensively for use in phytotoxicity tests. Genetic variability in responses to toxicants can occur in Lemna, and there are insufficient data to recommend a specific clone for testing. The US EPA test uses aseptic technique. The OECD test is not conducted axenically, but steps are taken at stages during the test procedure to keep contamination by other organisms to a minimum. Depending on the objectives of the test and the regulatory requirements, testing may be performed with renewal (semi-static and flow-through) or without renewal (static) of the test solution. Renewal is useful for substances that are rapidly lost from solution as a result of volatilisation, photodegradation, precipitation or biodegradation. [edit] Production of biopharmaceuticals Lemna has been transformed by molecular biologists to express proteins of pharmaceutical interest. Expression constructs were engineered to cause Lemna to secrete the transformed proteins into the growth medium at high yield. Since the Lemna is grown on a simple medium, this substantially reduces the burden of protein purification in preparing such proteins for medical use, promising substantial reductions in manufacturing costs.[3][4] In addition, the host Lemna can be engineered to cause secretion of proteins with human patterns of glycosylation, an improvement over conventional plant gene-expression systems.[5] Several such products are being developed, including monoclonal antibodies. [edit] Scientific farming High amounts of duck weed with a high protein content can be achieved by careful control of the growing conditions. Even though duckweed can tolerate the temperature of 6 to 33 C,the appropriate temperature range for a good harvest is 20 to 28 C. The acceptable ph range is 5 to 9, although better growth is possible in the ph range of 6.5 to 7.5. A minimum water depth of 1 ft is required. A sample of 20m.M Urea provides a protein content of 45%. Water could contain 60 mg/l of soluble nitrogen and 1 mg/l of phosphorus. Fertiliser is required on a daily basis. Duckweed can be farmed organically, with nutrients being supplied from for example cattle dung, pig waste, biogas plant slurry, or any other organic matter in slurry form. Because of the rapid growth, daily harvesting is necessary to achieve optimal yields. Harvesting is done such that less than a kilogram per square metre of duckweed remains. A duckweed farm can produce 10 to 30 tons of dried duckweed per hectare per year.[6]

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69 Σύγκριση ΠΚΘ (PCD) σε φυτά και ζώα Kuriyama and Fukuda Current Opinion in Plant Biology Volume 5, 2002, P:

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