Meiosis is a fundamental process in all sexual organisms that ensures fertility and genome stability and creates genetic diversity. For each of these outcomes, the exclusive formation of crossovers between homologous chromosomes is needed. This is more difficult to achieve in polyploid species which have more than 2 sets of chromosomes able to recombine. In this review, we describe how meiosis and meiotic recombination ‘deviate' in polyploid plants compared to diploids, and give an overview of current knowledge on how they are regulated. See also the sister article focusing on animals by Stenberg and Saura in this themed issue.

Akiyama T, Ohuchi T, Sumida S, Matsumoto K, Toyoshima K: Phosphorylation of the retinoblastoma protein by cdk2. Proc Natl Acad Sci USA 89:7900-7904 (1992).
Al-Kaff N, Knight E, Bertin I, Foote T, Hart N, et al: Detailed dissection of the chromosomal region containing the Ph1 locus in wheat Triticumaestivum: with deletion mutants and expression profiling. Ann Bot 101:863-872 (2008).
Armstrong SJ, Caryl AP, Jones GH, Franklin FCH: Asy1, a protein required for meiotic chromosome synapsis, localizes to axis-associated chromatin in Arabidopsis and Brassica. J Cell Sci 115:3645-3655 (2002).
Benavente E, Orellana J: Chromosome differentiation and pairing behavior of polyploids: an assessment of preferential metaphase I associations in colchicine-induced autotetraploid hybrids within the genus Secale. Genetics 128: 433-442 (1991).
Berger F, Twell D: Germline specification and function in plants. Annu Rev Plant Biol 62:461-484 (2011).
Boden SA, Langridge P, Spangenberg G, Able JA: TaAsy1 promotes homologous chromosome interactions and is affected by deletion of Ph1. Plant J 57:487-497 (2009).
Brownfield L, Köhler C: Unreduced gamete formation in plants: mechanisms and prospects. J Exp Bot 62:1659-1668 (2011).
Brubaker CL, Paterson AH, Wendel JF: Comparative genetic mapping of allotetraploid cotton and its diploid progenitors. Genome 42:184-203 (1999).
Brush GS, Najor NA, Dombkowski AA, Cukovic D, Sawarynski KE: Yeast IME2 functions early in meiosis upstream of cell cycle-regulated SBF and MBF targets. PLoS One 7:e31575 (2012).
Carlton PM, Farruggio AP, Dernburg AF: A link between meiotic prophase progression and crossover control. PLoS Genet 2:e12 (2006).
Carvalho A, Delgado M, Barão A, Frescatada M, Ribeiro E, et al: Chromosome and DNA methylation dynamics during meiosis in the autotetraploid Arabidopsisarenosa. Sex Plant Reprod 23:29-37 (2010).
Ceoloni C, Strauss I, Feldman M: Effect of different doses of group-2 chromosomes on homoeologous pairing in intergeneric wheat hybrids. Can J Genet Cytol 28:240-246 (1986).
Chelysheva L, Grandont L, Vrielynck N, le Guin S, Mercier R, Grelon M: An easy protocol for studying chromatin and recombination protein dynamics during Arabidopsisthaliana meiosis: immunodetection of cohesins, histones and MLH1. Cytogenet Genome Res 129:143-153 (2010).
Chelysheva L, Vezon D, Chambon A, Gendrot G, Pereira L, et al: The Arabidopsis HEI10 is a new ZMM protein related to Zip3. PLoS Genet 8:e1002799 (2012).
Chen Z, Higgins JD, Hui JTL, Li J, Franklin FCH, Berger F: Retinoblastoma protein is essential for early meiotic events in Arabidopsis. EMBO J 30:744-755 (2011).
Cifuentes M, Eber F, Lucas MO, Lode M, Chèvre AM, Jenczewski E: Repeated polyploidy drove different levels of crossover suppression between homeologous chromosomes in Brassicanapus allohaploids. Plant Cell 22:2265-2276 (2010a).
Cifuentes M, Grandont L, Moore G, Chèvre AM, Jenczewski E: Genetic regulation of meiosis in polyploid species: new insights into an old question. New Phytol 186:29-36 (2010b).
Contreras A, Hale TK, Stenoien DL, Rosen JM, Mancini MA, Herrera RE: The dynamic mobility of histone H1 is regulated by cyclin/CDK phosphorylation. Mol Cell Biol 23:8626-8636 (2003).
Corredor E, Lukaszewski AJ, Pachón P, Allen DC, Naranjo T: Terminal regions of wheat chromosomes select their pairing partners in meiosis. Genetics 177:699-706 (2007).
Crismani W, Girard C, Froger N, Pradillo M, Santos JL, et al: FANCM limits meiotic crossovers. Science 336:1588-1590 (2012).
Crowley JG, Rees H: Fertility and selection in tetraploid Lolium. Chromosoma 24:300-308 (1968).
Cuñado N, Callejas S, García MJ, Fernández A, Santos JL: The pattern of zygotene and pachytene pairing in allotetraploid Aegilops species sharing the U genome. Theor Appl Genet 93:1152-1155 (1996a).
Cuñado N, Callejas S, Gracía MJ, Santos JL, Fernández A: Chromosome pairing in the allotetraploid Aegilopsbiuncialis and a triploid intergeneric hybrid. Genome 39:664-670 (1996b).
Cuñado N, García MJ, Callejas S, Fernández A, Santos JL: The pattern of zygotene and pachytene pairing in allotetraploid Aegilops species sharing the D genome. Theor Appl Genet 93:1175-1179 (1996c).
d'Erfurth I, Jolivet S, Froger N, Catrice O, Novatchkova M, et al: Mutations in AtPS1 (Arabidopsisthaliana parallel spindle 1) lead to the production of diploid pollen grains. PLoS Genet 4:e1000274 (2008).
d'Erfurth I, Jolivet S, Froger N, Catrice O, Novatchkova M, Mercier R: Turning meiosis into mitosis. PLoS Biol 7:e1000124 (2009).
Desai A, Chee PW, Rong J, May OL, Paterson AH: Chromosome structural changes in diploid and tetraploid A genomes of Gossypium. Genome 49:336-345 (2006).
Dong C, Whitford R, Langridge P: A DNA mismatch repair gene links to the Ph2 locus in wheat. Genome 45:116-124 (2002).
Dvořák J, Chen K-C, Giorgi B: The C-band pattern of a Ph- mutant of durum wheat. Can J Genet Cytol 26:360-363 (1984).
Evans E, Sugawara N, Haber JE, Alani E: The Saccharomycescerevisiae Msh2 mismatch repair protein localizes to recombination intermediates in vivo. Mol Cell 5:789-799 (2000).
Feldman M: The effect of chromosomes 5B, 5D, and 5A on chromosomal pairing in Triticumaestivum. Proc Natl Acad Sci USA 55:1447-1453 (1966).
Gaeta RT, Pires CJ: Homoeologous recombination in allopolyploids: the polyploid ratchet. New Phytol 186:18-28 (2010).
Garcia BA, Busby SA, Barber CM, Shabanowitz J, Allis CD, Hunt DF: Characterization of phosphorylation sites on histone H1 isoforms by tandem mass spectrometry. J Proteome Res 3:1219-1227 (2004).
Gillies CB: Chromosome pairing and fertility in polyploids, in Gillies CB (ed): Fertility and Chromosome Pairing: Recent Studies in Plants and Animals, pp 137-176 (CRC Press, Boca Raton 1989).
Greer E, Martín AC, Pendle A, Colas I, Jones AME, et al: The Ph1 locus suppresses Cdk2-type activity during premeiosis and meiosis in wheat. Plant Cell 24:152-162 (2012).
Griffiths S, Sharp R, Foote TN, Bertin I, Wanous M, et al: Molecular characterization of Ph1 as a major chromosome pairing locus in polyploid wheat. Nature 439:749-752 (2006).
Gymer PT, Whittington WJ: Hybrids between Loliumperenne and Festucapratensis. New Phytol 74:295-306 (1975).
Hamant O, Ma H, Cande WZ: Genetics of meiotic prophase I in plants. Annu Rev Plant Biol 57:267-302 (2006).
Hartfield M, Otto SP, Keightley PD: The role of advantageous mutations in enhancing the evolution of a recombination modifier. Genetics 184:1153-1164 (2010).
Hobolth P: Chromosome pairing in allohexaploid wheat var. Chinese spring. Transformation of multivalents into bivalents, a mechanism for exclusive bivalent formation. Carlsberg Res Commun 46:129-173 (1981).
Hollister JD, Arnold BJ, Svedin E, Xue KS, Dilkes BP, Bomblies K: Genetic adaptation associated with genome-doubling in autotetraploid Arabidopsis arenosa. PLoS Genet 8:e1003093 (2012).
Holm PB: Chromosome pairing and chiasma formation in allohexaploid wheat, Triticumaestivum analyzed by spreading of meiotic nuclei. Carlsberg Res Commun 51:239-294 (1986).
Holm PB: Chromosome pairing and synaptonemal complex formation in hexaploid wheat, nullisomic for chromosome 5B. Carlsberg Res Commun 53:91-110 (1988).
Holm PB, Wang X: The effect of chromosome 5B on synapsis and chiasma formation in wheat, Triticumaestivum cv. Chinese spring. Carlsberg Res Commun 53:191-208 (1988).
Jannoo N, Grivet L, David J, D'Hont A, Glaszmann JC: Differential chromosome pairing affinities at meiosis in polyploid sugarcane revealed by molecular markers. Heredity 93:460-467 (2004).
Jenczewski E, Alix K: From diploids to allopolyploids: the emergence of efficient pairing control genes in plants. Crit Rev Plant Sci 23:21-45 (2004).
Jenczewski E, Eber F, Grimaud A, Huet S, Lucas MO, et al: PrBn , a major gene controlling homeologous pairing in oilseed rape (Brassica napus) haploids. Genetics 164:645-653 (2003).
Jenkins G: Chromosome pairing in Triticumaestivum cv. Chinese Spring. Carlsberg Res Commun 48:255-283 (1983).
Jenkins G: Synaptonemal complex formation in hybrids of Lolium temulentum x Lolium perenne (L.). I. High chiasma frequency diploid. Chromosoma 92:81-88 (1985a).
Jenkins G: Synaptonemal complex formation in hybrids of Lolium temulentum x Lolium perenne (L.). II. Triploid. Chromosoma 92:387-390 (1985b).
Jenkins G: Synaptonemal complex formation in hybrids of Lolium temulentum x Lolium perenne (L.). III. Tetraploid. Chromosoma 93:413-419 (1986).
Jenkins G: Chromosome pairing and fertility in plant hybrids, in Gillies CB (ed): Fertility and Chromosome Pairing: Recent Studies in Plants and Animals, pp 109-135 (CRC Press, Boca Raton 1989).
Jenkins G, Rees H: Strategies of bivalent formation in allopolyploid plants. Proc R Soc London B, 243:209-214 (1991).
Jenkins G, Chatterjee R: Chromosome structure and pairing preferences in autotetraploid rye (Secale cereale). Genome 37:784-793 (1994).
Jenkins G, White J, Parker JS: Elimination of multivalents during meiotic prophase in Scilla autumnalis. II. Tetraploid. Genome 30:940-946 (1988).
Jiao Y, Wickett NJ, Ayyampalayam S, Chanderbali AS, Landherr L, et al: Ancestral polyploidy in seed plants and angiosperms. Nature 473:97-100 (2011).
Jones GH: Meiosis in autopolypioid Crepiscapillaris. III. Comparison of triploids and tetraploids; evidence for non independence of autonomous pairing sites. Heredity 73:215-219 (1994).
Jones GH, Vincent JE: Meiosis in allopolyploid Crepiscapillaris. II. Autotetraploids. Genome 37:497-505 (1994).
Jones M, Rees H, Jenkins G: Synaptonemal complex formation in Avena polyploids. Heredity 63:209-219 (1989).
Knight E, Greer E, Draeger T, Thole V, Reader S, et al: Inducing chromosome pairing through premature condensation: analysis of wheat interspecific hybrids. Funct Integr Genomics 10:603-608 (2010).
Larionov A, Krause A, Miller W: A standard curve based method for relative real time PCR data processing. BMC Bioinformatics 6:62 (2005).
Le Comber SC, Ainouche ML, Kovarik A, Leitch AR: Making a functional diploid: from polysomic to disomic inheritance. New Phytol 186:113-122 (2010).
Leflon M, Grandont L, Eber F, Huteau V, Coriton O, et al: Crossovers get a boost in Brassica allotriploid and allotetraploid hybrids. Plant Cell 22:2253-2264 (2010).
Li Z, Zhao C, Iglesias-Ussel MD, Polonskaya Z, Zhuang M, et al: The mismatch repair protein Msh6 influences the in vivo AID targeting to the Ig locus. Immunity 24:393-403 (2006).
Li J, Harper LC, Golubovskaya I, Wang CR, Weber D, et al: Functional analysis of maize RAD51 in meiosis and double-strand break repair. Genetics 176:1469-1482 (2007).
Lim KY, Werlemark G, Matyasek R, Bringloe JB, Sieber V, et al: Evolutionary implications of permanent odd polyploidy in the stable sexual, pentaploid of Rosacanina L. Heredity 94:501-506 (2005).
Lim KY, Soltis DE, Soltis PS, Tate J, Matyasek R, et al: Rapid chromosome evolution in recently formed polyploids in Tragopogon (Asteraceae). PLoS One 3:e3353 (2008).
Liu Z, Adamczyk K, Manzanares-Dauleux M, Eber F, Lucas MO, et al: Mapping PrBn and other quantitative trait loci responsible for the control of homeologous chromosome pairing in oilseed rape (Brassica napus L.) haploids. Genetics 174:1583-1596 (2006).
Lloyd AH, Milligan AS, Langridge P, Able JA: TaMSH7: a cereal mismatch repair gene that affects fertility in transgenic barley (Hordeum vulgare L.). BMC Plant Biol 7:67 (2007).
Loidl J: Synaptonemal complex spreading in Allium. II. Tetraploid A. vineale. Canadian J Genet Cytol 28:754-761 (1986).
Loidl J: SC-formation in some Allium species, and a discussion of the significance of SC-associated structures and of the mechanisms for presynaptic alignment. Pl Syst Evol 158:117-131 (1988).
Loidl J, Jones GH: Synaptonemal complex spreading in Allium. I. Triploid A. sphaerocephalon. Chromosoma 93:420-428 (1986).
Lukaszewski AJ, Kopecký D: The Ph1 locus from wheat controls meiotic chromosome pairing in autotetraploid rye (Secale cereale L.). Cytogenetic Genome Res 129:117-123 (2010).
Luo MC, Dubcovsky J, Dvorák J: Recognition of homeology by the wheat Ph1 locus. Genetics 144:1195-1203 (1996).
Martinez M, Cuñado N, Carcelén N, Romero C: The Ph1 and Ph2 loci play different roles in the synaptic behaviour of hexaploid wheat Triticumaestivum. Theor Appl Genet 103:398-405 (2001a).
Martinez M, Naranjo T, Cuadrado C, Romero C: The synaptic behaviour of Triticumturgidum with variables doses of the Ph1 locus. Theor Appl Genet 102:751-758 (2001b).
Martinez-Pérez E, Shaw P, Reader S, Aragón-Alcaide L, Miller T, Moore G: Homologous chromosome pairing in wheat. J Cell Sci 112:1761-1769 (1999).
Martinez-Perez E, Shaw PJ, Moore G: Polyploidy induces centromere association. J Cell Biol 148:233-238 (2000).
Martinez-Perez E, Shaw P, Aragon-Alcaide L, Moore G: Chromosomes form into seven groups in hexaploid and tetraploid wheat as a prelude to meiosis. Plant J 36:21-29 (2003).
Mayrose I, Zhan SH, Rothfels CJ, Magnuson-Ford K, Barker MS, et al: Recently formed polyploid plants diversify at lower rates. Science 333:1257 (2011).
Mello-Sampayo T: Homoeologous pairing in pentaploid hybrids of wheat, in Finlay KW, Shepherd KW (eds): Proceedings of the Third International Wheat Genetics Symposium, pp 179-184 (Butterworths Australian Academy of Sciences, Canberra 1968).
Mello-Sampayo T, Canas AP: Suppressors of meiotic chromosome pairing in common wheat, in Sears LMS, Sears ER (eds): Proceedings of the Fourth International Wheat Genetics Symposium, pp 709-713 (University of Missouri, Columbia 1973).
Mikhailova EI, Naranjo T, Shepherd K, Wennekes-van Eden J, Heyting C, de Jong JH: The effect of the wheat Ph1 locus on chromatin organisation and meiotic chromosome pairing analysed by genome painting. Chromosoma 107:339-350 (1998).
Miller TE, Reader SM, Gale MD: The effect of homoeologous group 3 chromosomes on chromosome pairing and crossability in Triticum aestivum. Canadian J Genet Cytol 25:634-641 (1983).
Naranjo T: Finding the correct partner: the meiotic courtship. Scientifica DOI: 10.6064/2012/ 509073 (2012).
Neale MJ, Keeney S: Clarifying the mechanics of DNA strand exchange in meiotic recombination. Nature 442:153-158 (2006).
Newton WCF, Darlington CD: Meiosis in polyploids. I. Triploid and pentaploid tulips. J Genet 21:1-15 (1929).
Nicolas SD, Leflon M, Monod H, Eber F, Coriton O, et al: Genetic regulation of meiotic cross-overs between related genomes in Brassicanapus haploids and hybrids. Plant Cell 21: 373-385 (2009).
Norrmann GA, Quarin CL: Permanent odd ploidy in a grass (Andropogonternatus). Genome 29:340−344 (1987).
Ortega S, Prieto I, Odajima J, Martín A, Dubus P, Sotillo R, et al: Cyclin-dependent kinase 2 is essential for meiosis but not for mitotic cell division in mice. Nat Genet 35:25-31 (2003).
Osman K, Higgins JD, Sanchez-Moran E, Armstrong SJ, Franklin FC: Pathways to meiotic recombination in Arabidopsisthaliana. New Phytol 190:523-544 (2011).
Parisod C, Holderegger R, Brochmann C: Evolutionary consequences of autopolyploidy. New Phytol 186:5-17 (2010).
Pecinka A, Fang W, Rehmsmeier M, Levy AA, Mittelsten Scheid O: Polyploidization increases meiotic recombination frequency in Arabidopsis. BMC Biol 9:24 (2011).
Pradillo M, López E, Linacero R, Romero C, Cuñado N, et al: Together yes, but not coupled: new insights into the roles of RAD51 and DMC1 in plant meiotic recombination. Plant J 69:921-933 (2012).
Prieto P, Shaw P, Moore G: Homologue recognition during meiosis is associated with a change in chromatin conformation. Nat Cell Biol 6:906-908 (2004).
Ramsey J, Schemske DW: Neopolyploidy in flowering plants. Annu Rev Ecol Syst 33:589-639 (2002).
Rasmussen SW: Chromosome pairing in autotetraploid Bombyx males. Inhibition of multivalent correction by crossing over. Carlsberg Res Commun 52:211-242 (1987).
Rasmussen SW, Holm PB, Lu BC, Zickler D, Sage J: Synaptonemal complex formation and distribution of recombination nodules in pachytene trivalents of triploid Coprinuscinereus. Carlsberg Res Commun 46:347-360 (1981).
Riley R, Chapman V, Kimber G: Position of the gene determining the diploid-like meiotic behaviour of wheat. Nature 186:259-260 (1960).
Salmon A, Flagel L, Ying B, Udall JA, Wendel JF: Homeologous nonreciprocal recombination in polyploid cotton. New Phytol 186:123-134 (2010).
Sanchez-Moran E, Santos JL, Jones GH, Franklin FCH: ASY1 mediates AtDMC1-dependent interhomolog recombination during meiosis in Arabidopsis. Genes Dev 21:2220-2233 (2007).
Santos JL, Alfaro D, Sanchez-Moran E, Armstrong SJ, Franklin FC, Jones GH: Partial diploidization of meiosis in autotetraploid Arabidopsisthaliana. Genetics 165:1533-1540 (2003).
Sears ER: Genetic control of chromosome pairing in wheat. Annu Rev Genet 10:31-51 (1976).
Sherman JD, Stack SM, Anderson LK: Two-dimensional spreads of synaptonemal complexes from solanaceous plants. IV. Synaptic irregularities. Genome 32:743-753 (1989).
Smith-White S: The life history and genetic system of Leucopogonjuniperinus. Heredity 9:79−91 (1955).
Stack S: Two-dimensional spreads of synaptonemal complexes from solanaceous plants. I. The technique. Stain Technol 57:265-272 (1982).
Stebbins GL Jr: Types of polyploids; their classifications and significance. Adv Genet 1:403-429 (1947).
Sutton T, Whitford R, Baumann U, Dong C, Able JA, Langridge P: The Ph2 pairing homoeologous locus of wheat (Triticum aestivum): identification of candidate meiotic genes using a comparative genetics approach. Plant J 36:443-456 (2003).
Suwabe K, Morgan C, Bancroft I: Integration of Brassica A genome genetic linkage map between Brassicanapus and B. rapa. Genome 51:169-176 (2008).
Sved JA: The relationship between diploid and tetraploid recombination frequencies. Heredity 19:585-596 (1964).
Szadkowski E, Eber F, Huteau V, Lodé M, Huneau C, et al: The first meiosis of resynthesized Brassicanapus, a genome blender. New Phytol 186:102-112 (2010).
Szwarcwort-Cohen M, Kasulin-Boneh Z, Sagee S, Kassir Y: Human Cdk2 is a functional homolog of budding yeast Ime2, the meiosis-specific Cdk-like kinase. Cell Cycle 8:647-654 (2009).
Tam SM, Hays JB, Chetelat RT: Effects of suppressing the DNA mismatch repair system on homeologous recombination in tomato. Theor Appl Genet 123:1445-1458 (2011).
Thomas HW, Thomas BJ: Synaptonemal complex formation in two allohaxaploid Festuca species and a pentaploid hybrid. Heredity 71:305-311 (1993).
Tiang CL, He Y, Pawlowski WP: Chromosome organization and dynamics during interphase, mitosis, and meiosis in plants. Plant Physiol 158:26-34 (2012).
Wang K, Tang D, Wang M, Lu J, Yu H, et al: MER3 is required for normal meiotic crossover formation, but not for presynaptic alignment in rice. J Cell Sci 122:2055-2063 (2009).
Weismann A: The Germ-Plasm: a Theory of Heredity (C. Scribner's Sons, New York 1893).
White J, Jenkins G, Parker JS: Elimination of multivalents during meiotic prophase in Scillaautumnalis. I. Diploid and triploid. Genome 30:930-939 (1988).
Wood TE, Takebayashi N, Barker MS, Mayrose I, Greenspoon PB, Rieseberg LH: The frequency of polyploid speciation in vascular plants. Proc Natl Acad Sci USA 106:13875-13879 (2009).
Xiong Z, Gaeta RT, Pires JC: Homeologous shuffling and chromosome compensation maintain genome balance in resynthesized allopolyploid Brassicanapus. Proc Natl Acad Sci USA 108:7908-7913 (2011).
Youds JL, Boulton SJ: The choice in meiosis - defining the factors that influence crossover or non-crossover formation. J Cell Sci 124:501-513 (2011).
Yousafzai FK, Al-Kaff N, Moore G: The molecular features of chromosome pairing at meiosis: the polyploid challenge using wheat as a reference. Funct Integr Genomics 10:147-156 (2010).
Zickler D: From early homologue recognition to synaptonemal complex formation. Chromosoma 115:158-174 (2006).
Zickler D, Kleckner N: Meiotic chromosomes: integrating structure and function. Annu Rev Genet 33:603-754 (1999).
Zielinski M-L, Mittelsten Scheid O: Meiosis in polyploid plants, in Soltis PS, Soltis DE (eds): Polyploidy and Genome Evolution, pp 33-56 (Springer-Verlag, Berlin 2012).
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.