The Moss- Physcomitrella patens : A Novel Model System for Plant Development and Genomic Studies

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The moss P.patens has been used as a versatile experimental model organism for the past 80 years and it falls in the division Bryophyta. Being relatively simple in morphology and it generates only few tissues that contain limited number of cell fates (Mark leech et al., 1993), it is extensively being undertaken by plant biologists on both basic and applied strategies covering major areas namely developmental biology, evolution, systems biology, biotechnology ,biodiversity etc., As the organism is predominantly haploid in nature, it is evident that it could allow to develop insights on straight forward investigation/understanding of plant systems and hence, it is amenable for genetic and molecular level studies (Cove., 2009). The availability of complete genome sequence information, genetic and physical map ease the utilization of P.patens in all most all the fields of biology (Yasuko Kamisugi., 2008). It is the only land plant with an efficient system of homologous recombination in its nuclear DNA by which specific gene targeting could be achieved and the strategy of loss of function mutants can be generated by RNAi approach. In this context, the functional genomics of P.patens helps in identifying novel genes which could be employed in metabolic engineering and stress tolerance like drought, salt and osmotic stress thus helps in improving the crop plant performance. Moreover, it serves as a valuable platform for the production of recombinant pharmaceuticals (Anna K. Beike., 2010) Thus, the transfer of novel genes from P.patens has a greater biotechnological impact and may help in better public acceptance. Hence, this presentation aims to confine the advantages of this model plant in plant molecular research by discussing its efficiency in reproduction, range of technologies applied, some interesting characteristic features behind this model and chosen case studies will establish the model behaving as a well-versed medium for wide variety of approaches

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The Moss- Physcomitrella patens : A Novel Model System for Plant Development and Genomic Studies

  1. 1. Overview Introduction  Drug production Established models  Epigenetic regulation Emerging model system  Moss culture Species fact sheet  Abiotic stress tolerance Timescale of evolution  Gene silencing Life cycle  Metabolic engineering Comparative studies  Experimental evidences
  2. 2. Ultimate goal of modern biology-relationship between biologicalsystems , presence and activity ofgenesModel systems serve as theexcellent platforms for exploringthe biological relationships andfunctions [Didier Schaefer.,2002]
  3. 3.  Physcomitrellahas been developed as a model system to study plant gene function Versatile model First established as a laboratory experimental system in the 1920s by Fritz von Wettstein (1924) [Cove et al., 1993]
  4. 4. Bryophyta are the simplestand ancient lineage of landplants It includes mosses, liverwortsand hornworts The mosses and floweringplants diverged more than 450million years ago. [Henrik Toft et al., 2009]
  5. 5. Models like Physcomitrella patens serves solvinginquisitive puzzles in plant biological systems
  6. 6. Kingdom Plantae Plants Division Bryophyta Mosses Subdivision Musci Class Bryopsida -True mosses Subclass Bryidae Order Funariales Family Funariaceae Genus Physcomitrella Bruch & Schimp. Species Physcomitrella patens(Hedw.) Bruch & Schimp. [Source:USDA.gov, NRCS ]
  7. 7. [Knight.,2009]
  8. 8. Physcomitrella is well-placed phylogenetically to provide important comparisonswith the flowering plants [Michael Prigge et al., 2010]
  9. 9. Distinguishing features of Physcomitrella patens P. patens is a monoecious moss- requires very simple growth conditions It is a terrestrial non vascular plant Relatively simple morphology, with fewer cell fates than in flowering plants. [Mark leech et al .,1993]
  10. 10. Spore (n) Sporophyte (2n) Gametophore (n)Gametophore Colony (n) Protonema (n) [Sung Hyun Cho.et al.,2007]
  11. 11. Systems biologyDNA barcodingDNA barcoding
  12. 12. Bryotechnology Abiotic stress toleranceApplied studies biopharmaceutical
  13. 13. [Tomoaki Nishiyama et al.,2003]
  14. 14. Bryology [Anna K. Beike et al., 2010]
  15. 15. The assembled P. patens genome (511 Mb) -released bythe Joint Genome Institute [Ralf Reski.,2005]Transcriptomic analyses illustrate commonalitiesamong plant lineages in gene content, structure,and regulation [Ralph Quatrano.,2007]
  16. 16. Sequence-anchored geneticlinkage map for the moss,P.patens has been established [Yasuko Kamisugi.,2008]
  17. 17. More than 2,50,000 ESTs are available covering 95 % of mosstranscriptome [Rensing et al., 2002]One-quarter genome contains genes with no known function –keyto identify new and novel gene functions. [David Cove.,2009]
  18. 18. Phytohormones like auxin , cytokinin,ABAand photomorphogenetic pigments arefound to be intact in P.patens [Cove et al., 2009]
  19. 19. Versatility…A remarkable feature P.patens is its ability toincorporate transforming DNA at targeted sites-Homologous recombination [Yasuko et al.,2006]Efficient system for reverse genetics [Strepp et al., 1998]
  20. 20. Genome analyses of the moss P.patens has revealed -57 familiesof nuclear genes were acquired from prokaryotes, fungi or viruses [Jipei Yue et al.,2012]
  21. 21. Horizontal gene transfer [Jipei Yue., 2012]
  22. 22. [HK Stenoien., 2005]
  23. 23. [Anna Beike et al ., 2010]
  24. 24. Epigenetic regulation…Epigenetic regulation…Protoplasts of the moss P.patens easily regenerate intoprotonema and therefore provide an ideal system toexplore how differentiated cells can be reprogrammed toproduce stem cells. [Lihong Xiao et al .,2012] [Bestor.,1988]
  25. 25. [Daniel Lang et al., 2008]
  26. 26. Culturing the mossCulturing the moss Continuous light from fluorescent tubes at anintensity of between 5 and 20 W/m2 Either on solid and liquid culture High capacity of regeneration Axenic growth Temperatures between 24°Cand 26°C [Cove.,2005]
  27. 27. Abiotic Stress tolerance in P.patens [Anna Beike et al ., 2010]
  28. 28. P.patens is highly tolerant against drought, saltand osmotic stress Tolerates water loss of up to 92% and were able torecover successfully Tolerates up to 350mM of NaCl and 500mM of sorbitol [Wolf et al., 2005]
  29. 29. 439 genes encoding transcription –associatedproteins in response to salt stress and ABA wasreported by microarray expression analysis [Sandra Richard et al., 2010]
  30. 30. Breakthrough technology… miRNA important regulators of gene expression for both plants and animals miRNA families are found to be conserved in evolution
  31. 31. Genome-wide expression analyses inArabidopsis - high specificity of amiRNAs amiRNAs can be designed to target any geneof interest- functional gene analysis
  32. 32. amiRNA expression in P.patens Tested for amiRNA function in Physcomitrella Gene PpFtsZ2-1, which is required for chloroplastdivision PpGNT1 gene encoding an N-acetylglucosaminyltransferase [Basel Khraiwesh et al., 2008]
  33. 33. LC-PUFAs important for human diet-C22 PUFAs Marine fish and algal oils chief sourceBut…High production cost,diminishing feed stock limitthe supply
  34. 34. Requires a economic and sustainable source…. Metabolic engineering of an artificial pathway thatactivates the production of C22-PUFAs in P.patens Production of Docosatetraenoic acid (ADA) and n-3docosapentaenoic acid (DPA) Pavlova sp. Encodes D5-elongase Transgenic P.patens with vegetable oil supplementation.
  35. 35. [Pichit et al.,2012]
  36. 36. Experimental evidences I. a.Osmotic stress treatments
  37. 37. I.b.Dehydration treatment [Wolf et al., 2005]
  38. 38. II. Gene silencing by amiRNAOverexpression construct PCR screen
  39. 39. RACE PCR for amiRNA transgenic lines RNA gel blot analysis
  40. 40. [Basel Khraiwesh et al., 2008]
  41. 41. III. Metabolic engineeringStructure of pMDC43-PsELO5 Primers used for PCR amplification
  42. 42. Comparison of ADA and ɷ -3DPA production ADA-2.3% and DPA -1.1% of total fatty acids
  43. 43. Southern blotting of P.patens [Pichit et al.,2012]
  44. 44. IMSC www.moss-stock-center.org
  45. 45. To conclude…
  46. 46. Moss researcher consortium (left to right): Stefan Rensing, AndyCuming, Tomoaki Nishiyama, Ralf Reski, Mitsuyasu Hasebe, RalphQuatrano, Brent Mishler, David Cove Source: http://www.mossgenome.org/members.php
  47. 47. Dr.Meena kapoorUniversity school of biotechnology,Guru Gobind Singh Indraprastha University,New Delhi
  48. 48. “In the post-genomic era,……………..to underline the most important contributions broughtto science and, further, to draw attention tonewcomers in the field, that are expected to fill upthe gaps and answer the most specific question weface in biology,………………………….is possible by the use of such “ClassicalPlant Models” [Daniel ., 2009]
  49. 49. Discussion…

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