Fertilization Recovery after Defective Sperm Cell Release in Arabidopsis

Kasahara, Ryushiro D.; Maruyama, Daisuke; Hamamura, Yuki; Sugihara, Takashi; Twell, David; Higashiyama, Tetsuya

doi:10.1016/j.cub.2012.03.069

Cited by 120 publications

(140 citation statements)

References 29 publications

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“…x 2 analysis was used to test for significant deviation from the expected ratio of 1:1 if there was no rescue of failed division (i.e., 50% tricellular and 50% bicellular pollen); **P < 0.01, ***P < 0.001. ns, not significant. In six observations of single gamete discharge, fertilization of the egg or central cell did not occur (Figures 6H to 6M; Supplemental Movie 1 and 2), similar to previous observations of mutant duo3 germ cells and gcs1/hap2 sperm cells (Kasahara et al, 2012). Given that daz1 daz2 double mutant gametes are not competent for fertilization, we monitored gamete differentiation by introducing markers for two DUO1 target genes, the male gamete-specific histone H3.3 variant HTR10/MGH3 (Okada et al, 2005) and the sperm plasma membrane protein GCS1/HAP2, which is required for gamete fusion (Mori et al, 2006;von Besser et al, 2006).…”

Section: Daz1/daz2-dependent Pathways Are Also Required For Gamete DIsupporting

confidence: 69%

“…The frequency of unfertilized ovules was 41.8 and 34.9%, respectively, which is less than the 50% expected based on the 1:1 segregation of wild-type and mutant pollen ( Figure 6G). These data are consistent with the secondary fertilization of some ovules by wild-type pollen tubes after initial entry of a mutant pollen tube (Beale et al, 2012;Kasahara et al, 2012). To directly investigate fertilization, we used a semi-in vitro assay (Kasahara et al, 2012) to observe the fate of single daz1 daz2 gametes released into the embryo sac.…”

Section: Daz1/daz2-dependent Pathways Are Also Required For Gamete DIsupporting

confidence: 64%

“…These data are consistent with the secondary fertilization of some ovules by wild-type pollen tubes after initial entry of a mutant pollen tube (Beale et al, 2012;Kasahara et al, 2012). To directly investigate fertilization, we used a semi-in vitro assay (Kasahara et al, 2012) to observe the fate of single daz1 daz2 gametes released into the embryo sac. Briefly, sperm nuclei were labeled with ProDUO1:H2B-tdTomato and nuclei of female gametophyte accessory cells were labeled with ProACT11:H2B-GFP.…”

Section: Daz1/daz2-dependent Pathways Are Also Required For Gamete DIsupporting

confidence: 64%

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An EAR-Dependent Regulatory Module Promotes Male Germ Cell Division and Sperm Fertility in Arabidopsis

et al. 2014

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The production of the sperm cells in angiosperms requires coordination of cell division and cell differentiation. In Arabidopsis thaliana, the germline-specific MYB protein DUO1 integrates these processes, but the regulatory hierarchy in which DUO1 functions is unknown. Here, we identify an essential role for two germline-specific DUO1 target genes, DAZ1 and DAZ2, which encode EAR motif-containing C 2 H 2 -type zinc finger proteins. We show that DAZ1/DAZ2 are required for germ cell division and for the proper accumulation of mitotic cyclins. Importantly, DAZ1/DAZ2 are sufficient to promote G2-to M-phase transition and germ cell division in the absence of DUO1. DAZ1/DAZ2 are also required for DUO1-dependent cell differentiation and are essential for gamete fusion at fertilization. We demonstrate that the two EAR motifs in DAZ1/DAZ2 mediate their function in the male germline and are required for transcriptional repression and for physical interaction with the corepressor TOPLESS. Our findings uncover an essential module in a regulatory hierarchy that drives mitotic transition in male germ cells and implicates gene repression pathways in sperm cell formation and fertility.

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Section: Daz1/daz2-dependent Pathways Are Also Required For Gamete DIsupporting

confidence: 69%

Section: Daz1/daz2-dependent Pathways Are Also Required For Gamete DIsupporting

confidence: 64%

Section: Daz1/daz2-dependent Pathways Are Also Required For Gamete DIsupporting

confidence: 64%

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An EAR-Dependent Regulatory Module Promotes Male Germ Cell Division and Sperm Fertility in Arabidopsis

et al. 2014

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“…The impaired degeneration of the remaining synergid in ap1g/+ might be a secondary effect due to the failure of pollen tube discharge (23,24). Although as a fertilization recovery strategy after defective sperm cell release, nondegenerating synergids keep sending out attractive signals for pollen tubes (26,38), no supernumerary pollen tubes were observed in ap1g/+ FGs likely due to reduced pollen tube guidance.…”

Section: Discussionmentioning

confidence: 98%

AP1G mediates vacuolar acidification during synergid-controlled pollen tube reception

Wang

Feng

Liu

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Double fertilization in angiosperms requires the delivery of immotile sperm through pollen tubes, which enter embryo sacs to initiate synergid degeneration and to discharge. This fascinating process, called pollen tube reception, involves extensive communications between pollen tubes and synergids, within which few intracellular regulators involved have been revealed. Here, we report that vacuolar acidification in synergids mediated by AP1G and V-ATPases might be critical for pollen tube reception. Functional loss of AP1G or VHA-A, encoding the γ subunit of adaptor protein 1 or the shared component of two endomembrane V-ATPases, respectively, impaired synergid-controlled pollen tube reception and caused partial female sterility. AP1G works in parallel to the plasma membrane-associated receptor FERONIA in synergids, suggesting that synergid-mediated pollen tube reception requires proper sorting of vacuolar cargos by AP1G. Although AP1G did not mediate the targeting of V-ATPases, AP1G loss of function or the expression of AP1G-RNAi compromised vacuolar acidification mediated by V-ATPases, implying their genetic interaction. We propose that vacuolar acidification might represent a distinct cell-death mechanism specifically adopted by the plant phylum, which is critical for synergid degeneration during pollen tube reception. . The female gametophyte (FG), i.e., the embryo sac, is formed inside the ovules and contains an egg cell, a central cell, two synergid cells, and three antipodal cells (3). Upon landing on a receptive pistil, a pollen grain forms a long cylindrical extension, called a pollen tube, which extends inside female sporophytic tissues. To deliver immotile sperm, pollen tubes perceive attractive signals sent out by the FG, change their growth axis, and finally enter the embryo sacs through the micropyle (1-4). A process called "pollen tube reception" instructs the cessation and discharge of the penetrating pollen tube, leading to sperm release and fertilization (1-4).Studies have uncovered key female factors controlling pollen tube reception, including FERONIA (FER) (5-7), LORELEI (LRE) (8, 9), and early nodulin-like proteins (ENODLs) (10) and NORTIA (NTA) (11). These synergid receptors likely operate in the same genetic pathway (10-12) whose functional loss caused the failure of pollen tube discharge and led to reduced female fertility (5-9, 11). Male ligands are yet to be identified. However, recent studies showed that the production of reactive oxygen species (ROS) and Ca 2+ spiking are downstream events of FER-controlled pollen tube reception (13-16).Synergid degeneration, a form of programmed cell death (PCD), is a key step during pollen tube reception. Between the two synergid cells, a receptive synergid cell is the one that succeeds in interacting with the pollen tube and induces it to burst and undergoes cell death first. The other synergid cell that continues to persist and then undergoes cell death orchestrated by the fertilized egg cell and the central cell is the persistent synergid (3,11,1...

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“…25 However, it has been reported that additional pollen tubes can invade the embryo sac [37][38][39] when the sperm cell-egg cell fusion and/or the sperm cell-central cell fusion does not progress successfully 40,41 . This suggests that the egg:sperm ratio can vary, and that penetration of extra pollen tubes into the embryo sac provides the opportunity for multiple sperm cells to fuse with an egg cell.…”

Section: Cmentioning

confidence: 99%