20. Baumberger N, Baulcombe DC (2005) Arabidopsis ARGONAUTE1 is an RNA Slicer that selectively recruits microRNAs and short interfering RNAs. Proc Natl Acad Sci U S A 102: 11928–11933. 21. Vaucheret H (2008) Plant ARGONAUTES. Trends Plant Sci 13: 350–358. 22. Bohmert K, Camus I, Bellini C, Bouchez D, Caboche M, et al. (1998) AGO1 defines a novel locus of Arabidopsis controlling leaf development. Embo J 17: 170–180. 23. Lynn K, Fernandez A, Aida M, Sedbrook J, Tasaka M, et al. (1999) The PINHEAD/ZWILLE gene acts pleiotropically in Arabidopsis development and has overlapping functions with the ARGONAUTE1 gene. Development 126: 469–481. 24. Moussian B, Schoof H, Haecker A, Jurgens G, Laux T (1998) Role of the ZWILLE gene in the regulation of central shoot meristem cell fate during Arabidopsis embryogenesis. Embo J 17: 1799–1809. 25. McConnell JR, Barton MK (1995) Effect of mutations in the PINHEAD gene of Arabidopsis on the formation of shoot apical meristems. Dev Genet 16: 358–366. 26. Brodersen P, Sakvarelidze-Achard L, Bruun-Rasmussen M, Dunoyer P, Yamamoto YY, et al. (2008) Widespread translational inhibition by plant miRNAs and siRNAs. Science 320: 1185–1190. 27. Mallory AC, Hinze A, Tucker MR, Bouche N, Gasciolli V, et al. (2009) Redundant and specific roles of the ARGONAUTE proteins AGO1 and ZLL in development and small RNA-directed gene silencing. PLoS Genet 5: e1000646. doi:10.1371/journal.pgen.1000646. 28. Cheng Y, Kato N, Wang W, Li J, Chen X (2003) Two RNA binding proteins, HEN4 and HUA1, act in the processing of AGAMOUS pre-mRNA in Arabidopsis thaliana. Dev Cell 4: 53–66. 29. Emery JF, Floyd SK, Alvarez J, Eshed Y, Hawker NP, et al. (2003) Radial patterning of Arabidopsis shoots by class III HD-ZIP and KANADI genes. Curr Biol 13: 1768–1774. 30. Mallory AC, Reinhart BJ, Jones-Rhoades MW, Tang G, Zamore PD, et al. (2004) MicroRNA control of PHABULOSA in leaf development: importance of pairing to the microRNA 59 region. Embo J 23: 3356–3364. 31. Chen X, Meyerowitz EM (1999) HUA1 and HUA2 are two members of the floral homeotic AGAMOUS pathway. Mol Cell 3: 349–360. 32. Chen X, Liu J, Cheng Y, Jia D (2002) HEN1 functions pleiotropically in Arabidopsis development and acts in C function in the flower. Development 129: 1085–1094. 33. Li J, Chen X (2003) PAUSED, a putative exportin-t, acts pleiotropically in Arabidopsis development but is dispensable for viability. Plant Physiol 132: 1913–1924. 34. Wang W, Chen X (2004) HUA ENHANCER3 reveals a role for a cyclin- dependent protein kinase in the specification of floral organ identity in Arabidopsis. Development 131: 3147–3156. 35. Western TL, Cheng Y, Liu J, Chen X (2002) HUA ENHANCER2, a putative DExH-box RNA helicase, maintains homeotic B and C gene expression in Arabidopsis. Development 129: 1569–1581. AGO10 and Floral Stem Cell Termination 36. Tucker MR, Hinze A, Tucker EJ, Takada S, Jurgens G, et al. (2008) Vascular signalling mediated by ZWILLE potentiates WUSCHEL function during shoot meristem stem cell development in the Arabidopsis embryo. Development 135: 2839–2843. 37. Mayer KF, Schoof H, Haecker A, Lenhard M, Jurgens G, et al. (1998) Role of WUSCHEL in regulating stem cell fate in the Arabidopsis shoot meristem. Cell 95: 805–815. 38. Clark SE, Running MP, Meyerowitz EM (1995) CLAVATA3 is a specific regulator of shoot and floral meristem development affecting the same processes as CLAVATA1. Development 121: 2057–2067. 39. Kidner CA, Martienssen RA (2005) The role of ARGONAUTE1 (AGO1) in meristem formation and identity. Dev Biol 280: 504–517. 40. Park W, Li J, Song R, Messing J, Chen X (2002) CARPEL FACTORY, a Dicer homolog, and HEN1, a novel protein, act in microRNA metabolism in Arabidopsis thaliana. Curr Biol 12: 1484–1495. 41. Baker CC, Sieber P, Wellmer F, Meyerowitz EM (2005) The early extra petals1 mutant uncovers a role for microRNA miR164c in regulating petal number in Arabidopsis. Curr Biol 15: 303–315. 42. McConnell JR, Barton MK (1998) Leaf polarity and meristem formation in Arabidopsis. Development 125: 2935–2942. 43. Liu Q, Yao X, Pi L, Wang H, Cui X, et al. (2008) The ARGONAUTE10 gene modulates shoot apical meristem maintenance and leaf polarity establishment by repressing miR165/166 in Arabidopsis. Plant J. 44. Wenkel S, Emery J, Hou BH, Evans MM, Barton MK (2007) A feedback regulatory module formed by LITTLE ZIPPER and HD-ZIPIII genes. Plant Cell 19: 3379–3390. 45. Qi Y, He X, Wang XJ, Kohany O, Jurka J, et al. (2006) Distinct catalytic and non-catalytic roles of ARGONAUTE4 in RNA-directed DNA methylation. Nature 443: 1008–1012. 46. Vaucheret H, Vazquez F, Crete P, Bartel DP (2004) The action of ARGONAUTE1 in the miRNA pathway and its regulation by the miRNA pathway are crucial for plant development. Genes Dev 18: 1187–1197. 47. Sun B, Xu Y, Ng KH, Ito T (2009) A timing mechanism for stem cell maintenance and differentiation in the Arabidopsis floral meristem. Genes Dev 23: 1791–1804. 48. Prigge MJ, Otsuga D, Alonso JM, Ecker JR, Drews GN, et al. (2005) Class III homeodomain-leucine zipper gene family members have overlapping, antago- nistic, and distinct roles in Arabidopsis development. Plant Cell 17: 61–76. 49. Zhou GK, Kubo M, Zhong R, Demura T, Ye ZH (2007) Overexpression of miR165 affects apical meristem formation, organ polarity establishment and vascular development in Arabidopsis. Plant Cell Physiol 48: 391–404. 50. Bowman JL, Smyth DR, Meyerowitz EM (1991) Genetic interactions among floral homeotic genes of Arabidopsis. Development 112: 1–20. 51. Pall GS, Codony-Servat C, Byrne J, Ritchie L, Hamilton A (2007) Carbodiimide-mediated cross-linking of RNA to nylon membranes improves the detection of siRNA, miRNA and piRNA by northern blot. Nucleic Acids Res 35: e60. PLoS Genetics | www.plosgenetics.org 14 March 2011 | Volume 7 | Issue 3 | e1001358