Double fertilization Hamamura.Nagahara and Higashivama 75 2.Kle shen in pollen de ery in 3. M- n ML:Usir 23. 2 ing th ception and f Me0eTaKenR4aniedtgs0otheEmbnologyolAngospems 2009.1913271新 25. n-D 9 o3 26. 2。 d time-la and 28 it of sp clei.By 29. 12epmpna8sa路en8m296atonn 15.Wetor2t5107S118 16 ntntTor o t2010137.i4731481. de enabled the zygote to avoid 18 ver GP, 3. 5e1595 by G s1. nsab as the N- ativ ntial eful f the mo te Pe Wong JL.Leydon AR.Joh MA: To ide on.theN www.sciencedirect.com Current Opinion in Plant:70-772. Kessler SA, Grossniklaus U: She’s the boss: signaling in pollen tube reception. Curr Opin Plant Biol 2011, 14:622-627. 3. Dresselhaus T, Lausser A, Marton ML: Using maize as a model to study pollen tube growth and guidance, cross-incompatibility and sperm delivery in grasses. Ann Bot 2011, 108:727-737. 4. Takeuchi H, Higashiyama T: Attraction of tip-growing pollen tubes by the female gametophyte. Curr Opin Plant Biol 2011, 14:614-621. 5. 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The authors performed time-lapse imaging of double fertilization and found three behavioral steps of the two sperm cells: rapid movement from the ruptured pollen tube, a stationary phase between the two female gametes, and gamete fusion leading to movement of sperm cell nuclei toward the target female nuclei. By labeling the two sperm cells differently with a photo-convertible fluorescent protein, they found no preference in fertilization targets between the front and back sperm cells of the male germ unit. 12. Twell D: Male gametogenesis and germline specification in flowering plants. Sex Plant Reprod 2011, 24:149-160. 13. Chevalier E, Loubert-Hudon A, Zimmerman EL, Matton DP: Cell￾cell communication and signalling pathways within the ovule: from its inception to fertilization. New Phytol 2011, 192:13-28. 14. Tian HQ, Yuan T, Russell SD: Relationship between double fertilization and the cell cycle in male and female gametes of tobacco. Sex Plant Reprod 2005, 17:243-252. 15. Weterings K, Russell SD: Experimental analysis of the fertilization process. Plant Cell 2004, 16(Suppl.):S107-S118. 16. Higashiyama T, Kuroiwa H, Kawano S, Kuroiwa T: Explosive discharge of pollen tube contents in Torenia fournieri. Plant Physiol 2000, 122:11-14. 17. Faure JE, Rotman N, Fortune P, Dumas C: Fertilization in Arabidopsis thaliana wild type: developmental stages and time course. Plant J 2002, 30:481-488. 18. Sandaklie-Nikolova L, Palanivelu R, King EJ, Copenhaver GP, Drews GN: Synergid cell death in Arabidopsis is triggered following direct interaction with the pollen tube. Plant Physiol 2007, 144:1753-1762. 19. Huck N, Moore JM, Federer M, Grossniklaus U: The Arabidopsis mutant feronia disrupts the female gametophytic control of pollen tube reception. Development 2003, 130:2149-2159. 20. Rotman N, Rozier F, Boavida L, Dumas C, Berger F, Faure JE: Female control of male gamete delivery during fertilization in Arabidopsis thaliana. Curr Biol 2003, 13:432-436. 21. Escobar-Restrepo JM, Huck N, Kessler S, Gagliardini V, Gheyselinck J, Yang WC, Grossniklaus U: The FERONIA receptor-like kinase mediates male-female interactions during pollen tube reception. Science 2007, 317:656-660. 22. Capron A, Gourgues M, Neiva LS, Faure JE, Berger F, Pagnussat G, Krishnan A, Alvarez-Mejia C, Vielle-Calzada JP, Lee YR et al.: Maternal control of male-gamete delivery in Arabidopsis involves a putative GPI-anchored protein encoded by the LORELEI gene. Plant Cell 2008, 20:3038-3049. 23. Kessler SA, Shimosato-Asano H, Keinath NF, Wuest SE, Ingram G, Panstruga R, Grossniklaus U: Conserved molecular components for pollen tube reception and fungal invasion. Science 2010, 330:968-971. In this study, nortia (nta) was identified as a female gametophytic mutant displaying pollen tube overgrowth in the female gametophyte, such as feronia ( fer). The NTA gene encodes a member of the Mildew Resistance Locus O (MLO) family, suggesting that pollen tube reception and fungal invasion share common components. Using fer/fer mutant plants, the authors also showed that FER was involved in powdery mildew infection as well as pollen tube reception. 24. Miyazaki S, Murata T, Sakurai-Ozato N, Kubo M, Demura T, Fukuda H, Hasebe M: ANXUR1 and 2, sister genes to FERONIA/ SIRENE, are male factors for coordinated fertilization. Curr Biol 2009, 19:1327-1331. 25. Boisson-Dernier A, Roy S, Kritsas K, Grobei MA, Jaciubek M, Schroeder JI, Grossniklaus U: Disruption of the pollen￾expressed FERONIA homologs ANXUR1 and ANXUR2 triggers pollen tube discharge. Development 2009, 136:3279-3288. 26. Antoine AF, Faure JE, Cordeiro S, Dumas C, Rougier M, Feijo JA: A calcium influx is triggered and propagates in the zygote as a wavefront during in vitro fertilization of flowering plants. Proc Natl Acad Sci USA 2000, 97:10643-10648. 27. Portereiko MF, Sandaklie-Nikolova L, Lloyd A, Dever CA, Otsuga D, Drews GN: NUCLEAR FUSION DEFECTIVE1 encodes the Arabidopsis RPL21M protein and is required for karyogamy during female gametophyte development and fertilization. Plant Physiol 2006, 141:957-965. 28. Maruyama D, Endo T, Nishikawa S: BiP-mediated polar nuclei fusion is essential for the regulation of endosperm nuclei proliferation in Arabidopsis thaliana. Proc Natl Acad Sci USA 2010, 107:1684-1689. 29. Mori T, Kuroiwa H, Higashiyama T, Kuroiwa T: GENERATIVE CELL SPECIFIC 1 is essential for angiosperm fertilization. Nat Cell Biol 2006, 8:64-71. 30. von Besser K, Frank AC, Johnson MA, Preuss D: Arabidopsis HAP2 (GCS1) is a sperm-specific gene required for pollen tube guidance and fertilization. Development 2006, 133:4761-4769. 31. Hirai M, Arai M, Mori T, Miyagishima SY, Kawai S, Kita K, Kuroiwa T, Terenius O, Matsuoka H: Male fertility of malaria parasites is determined by GCS1, a plant-type reproduction factor. Curr Biol 2008, 18:607-613. 32. Liu Y, Misamore MJ, Snell WJ: Membrane fusion triggers rapid degradation of two gamete-specific, fusion-essential proteins in a membrane block to polygamy in Chlamydomonas. Development 2010, 137:1473-1481. Both FUS1 and HAP2 (GCS1) of the green alga Chlamydomonas are expressed in the plus and the minus gametes, respectively, and are rapidly degradated after gamete fusion. The authors concluded that this rapid degradation of essential proteins enabled the zygote to avoid polygamy in Chlamydomonas. 33. Mori T, Hirai M, Kuroiwa T, Miyagishima SY: The functional domain of GCS1-based gamete fusion resides in the amino terminus in plant and parasite species. PLoS ONE 2010, 5:e15957. The authors performed an Arabidopsis gcs1 mutant complementation assay by transforming plants with modified versions of GCS1, of which various domains were disrupted, separated, or exchanged by GFP insertions. Expression and localization of transformed genes was visua￾lized by GFP fluorescence. The C-terminus of GCS1, a putative intracel￾lular region, was dispensable, whereas the N-terminus domain, a putative extracellular region, was essential for successful fertilization. Further￾more, an in vitro fertilization assay of the mouse malaria parasite Plas￾modium berghei possessing modified versions of GCS1 also represented less contribution of the C-terminus to gamete fusion in P. berghei. 34. Wong JL, Leydon AR, Johnson MA: HAP2(GCS1)-dependent gamete fusion requires a positively charged carboxy-terminal domain. PLoS Genet 2010, 6:e1000882. To identify the HAP2 (GCS1) functional region, the N-terminus and C-terminus of Arabidopsis HAP2 was exchanged with those of other Double fertilization Hamamura, Nagahara and Higashiyama 75 www.sciencedirect.com Current Opinion in Plant Biology 2012, 15:70–77