Chemical signaling for pollen tube guidance at a glance

Mizuta, Yoko; Higashiyama, Tetsuya

doi:10.1242/jcs.208447

Cited by 72 publications

(52 citation statements)

References 113 publications

(142 reference statements)

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“…In the amp1 mutant, 19% of the ovules showed EC1.1pro∷HTA6–3GFP expression in both synergid cells, whereas 26% of the ovules showed their expression in only one of the synergid cells (notably, 45% of the ovules have no detectable fluorescent signal) (Kong et al, 2015). The synergid cells play an important role in the pollen tube attraction, by secreting peptides (Mizuta and Higashiyama, 2018). Previously, we found that the laser disruption of the immature egg cells affects the cell differentiation for one of the synergid cells in the Torenia fournieri (Susaki et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

Dynamics of the cell fate specifications during female gametophyte development inArabidopsis

Susaki

Suzuki

Maruyama

et al. 2020

Preprint

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The female gametophytes of angiosperms contain cells with distinct functions, such as those that enable reproduction via pollen tube attraction and fertilization. Although the female gametophyte undergoes unique developmental processes, such as several rounds of nuclear division without cell plate formation, and the final cellularization, it remains unknown when and how the cell fate is determined during their development. Here, we visualized the living dynamics of female gametophyte development and performed transcriptome analysis of its individual cell types, to assess the cell fate specifications in Arabidopsis thaliana. We recorded time lapses of the nuclear dynamics and cell plate formation from the one-nucleate stage to the seven-cell stage after cellularization, using the in vitro ovule culture system. The movies showed that the nuclear division occurred along the micropylar-chalazal axis. During cellularization, the polar nuclei migrated while associating with forming edge of the cell plate. Then, each polar nucleus migrated to fuse linearly towards each other. We also tracked the gene expression dynamics and identified that the expression of the MYB98pro::GFP, a synergid-specific marker, was initiated before cellularization, and then restricted to the synergid cells after cellularization. This indicated that cell fates are determined immediately after cellularization. Transcriptome analysis of the female gametophyte cells of the wild type and myb98 mutant, revealed that the myb98 synergid cells had the egg cell-like gene expression profile. Although in the myb98, the egg cell-specific gene expressions were properly initiated only in the egg cells after cellularization, but subsequently expressed ectopically in one of the two synergid cells. These results, together with the various initiation timings of the egg cell-specific genes suggest the complex regulation of the individual gametophyte cells, such as cellularization-triggered fate initiation, MYB98-dependent fate maintenance, cell morphogenesis, and organelle positioning. Our system of live-cell imaging and cell-type-specific gene expression analysis provides insights into the dynamics and mechanisms of cell fate specifications in the development of female gametophytes in plants.

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Section: Discussionmentioning

confidence: 99%

Dynamics of the cell fate specifications during female gametophyte development inArabidopsis

Susaki

Suzuki

Maruyama

et al. 2020

Preprint

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“…Several mechanisms have been proposed to explain the precise growth of pollen tubes towards the ovules, including mechanical, chemotropic and physiological guidance cues (reviewed by Mizuta & Higashiyama, ). Our findings are consistent with an important role of DGK proteins in pollen tube growth and of DGK4 in tube guidance acting as a link between signalling pathways and secretion of cell wall material.…”

Section: Discussionmentioning

confidence: 99%

A role for diacylglycerol kinase 4 in signalling crosstalk during Arabidopsis pollen tube growth

et al. 2019

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Summary Diacylglycerol kinases (DGKs) play a major role in the production of phosphatidic acid (PtdOH) and were implicated in endomembrane trafficking and signalling cascades. In plants, the role of DGKs is less clear, as PtdOH seems to arise mostly from phospholipase D activity. Here, we investigated the function of the Arabidopsis gene encoding DGK4, which is highly expressed in pollen. In vitro, pollen tubes from homozygous dgk4 plants showed normal morphology, but reduced growth rate and altered stiffness and adhesion properties (revealed by atomic force microscopy). In vivo, dgk4 pollen was able to fertilize wild‐type ovules, but self‐pollination in dgk4 plants led to fewer seeds and shorter siliques. Phenotypic analysis revealed that the dgk4 mutation affects not only the male germ line but also the vegetative tissue. DGK4‐green fluorescent protein fusion imaging revealed a cytosolic localization with a slightly higher signal in the subapical or apical region. dgk4 pollen tubes were found to exhibit perturbations in membrane recycling, and lipid analysis revealed a minor increase of PtdOH concomitant with decreased phosphatidylcholine, compared with wild‐type. In vitro, DGK4 was found to exhibit kinase and guanylyl cyclase activity. Quantitative PCR data revealed downregulation of genes related to actin dynamics and phosphoinositide metabolism in mutant pollen, but upregulation of the DGK6 isoform. Altogether, these results are discussed considering a role of DGK4 in signalling cross‐talk.

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“…Fertilization is a key process for sexual reproduction, and an important point in this process is that the pollen tubes can reach the ovules. The synergid cells, in the embryo sac inside the ovule, produce signals to attract the pollen tube (Mizuta and Higashiyama, 2018). For pollen tubes to reach the ovules, cell wall modifications have to take place (Crawford and Yanofsky, 2008;Dresselhaus and Franklin-Tong, 2013).…”

Section: Introductionmentioning

confidence: 99%

New roles of NO TRANSMITTING TRACT and SEEDSTICK during medial domain development in Arabidopsis fruits

et al. 2018

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The gynoecium, the female reproductive part of the flower, is key for plant sexual reproduction. During its development, inner tissues such as the septum and the transmitting tract tissue, important for pollen germination and guidance, are formed. In Arabidopsis, several transcription factors are known to be involved in the development of these tissues. One of them is NO TRANSMITTING TRACT (NTT), essential for transmitting tract formation. We found that the NTT protein can interact with several gynoecium-related transcription factors, including several MADS-box proteins, such as SEEDSTICK (STK), known to specify ovule identity. Evidence suggests that NTT and STK control enzyme and transporterencoding genes involved in cell wall polysaccharide and lipid distribution in gynoecial medial domain cells. The results indicate that the simultaneous loss of NTT and STK activity affects polysaccharide and lipid deposition and septum fusion, and delays entry of septum cells to their normal degradation program. Furthermore, we identified KAWAK, a direct target of NTT and STK, which is required for the correct formation of fruits in Arabidopsis. These findings position NTT and STK as important factors in determining reproductive competence.

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Chemical signaling for pollen tube guidance at a glance

Cited by 72 publications

References 113 publications

Dynamics of the cell fate specifications during female gametophyte development inArabidopsis

Dynamics of the cell fate specifications during female gametophyte development inArabidopsis

A role for diacylglycerol kinase 4 in signalling crosstalk during Arabidopsis pollen tube growth

New roles of NO TRANSMITTING TRACT and SEEDSTICK during medial domain development in Arabidopsis fruits

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