Relatively high calcium is localized in synergid cells of wheat ovaries

Chaubal, R.; Reger, Bonnie J.

doi:10.1007/bf00198852

Cited by 67 publications

(30 citation statements)

References 27 publications

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“…The distribution of elements in regions of the ovary other than the egg apparatus did not change after pollination as compared to their distribution in unpollinated ovaries (Chaubal and Reger 1990). Pollen tubes were not visible in the ovary tissues; however pollen grains with tubes penetrating the stigma were visualized in each pistil examined with the SEM.…”

Section: Resultsmentioning

confidence: 83%

The dynamics of calcium distribution in the synergid cells of wheat after pollination

Chaubal

Reger

1992

Sexual Plant Reprod

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Sister synergids of wheat were examined for post-pollination calcium distribution using freeze-substitution fixation, scanning electron microscopy, and energy-dispersive X-ray microanalysis. At 15-30 min postpollination (before pollen-tube penetration and discharge), the sister synergids were similar in size and in elemental concentrations. Both synergids measured about the same as the egg and contained relatively high concentrations of calcium, potassium, and magnesium. The sister synergids remained identical even in an aberrant case where a pollen tube had penetrated, but not discharged into a synergid. After 30 rain post-pollination (after pollen-tube discharge), typically one of the sister synergids was reduced in size and devoid of high concentrations of elements. The other synergid initially remained unaltered and only later underwent slight size reduction; however, it retained high concentrations of elements. The results indicate that high concentrations of calcium, potassium, and magnesium are rapidly lost from a synergid following pollen-tube discharge. A hypothesis is proposed to explain the regulation of entry by only a single pollen tube into an embryo sac.

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Section: Resultsmentioning

confidence: 83%

The dynamics of calcium distribution in the synergid cells of wheat after pollination

Chaubal

Reger

1992

Sexual Plant Reprod

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“…7). Although calcium has been detected in the synergid cell and the neighboring extracellular matrix, as described above (Jensen, 1965;Chaubal and Reger, 1990, 1992a, 1992bHuang and Russell, 1992;Tirlapur et al, 1993;Tian and Russell, 1997;Kristó f et al, 1999), Ca 21 may play a primary role in pollen tube discharge, gamete fusion, or both, but not in species-related pollen tube attraction. In an Arabidopsis mutant in which a plasma membrane Ca 21 pump of the pollen tube, ACA9, is disrupted, the pollen tube arrives at the embryo sac but cannot discharge its contents to the receptive synergid cell and shows overgrowth in the embryo sac (Schiøtt et al, 2004).…”

Section: Discussionmentioning

confidence: 98%

“…In vitro test results suggest that calcium is an attractant derived from the pistil, in particular the ovule Machlis, 1962, 1964;Reger et al, 1992). Using various histochemical methods including calcium antimonate precipitation, proton-induced x-ray emission, and fluorescent calcium probes, high concentrations of calcium have been observed in synergid cells and the neighboring extracellular matrices in various species (Jensen, 1965;Chaubal and Reger, 1990, 1992a, 1992bHuang and Russell, 1992;Tirlapur et al, 1993;Tian and Russell, 1997), including T. fournieri (Kristó f et al, 1999). The second potential attractant is ZmEA1 (Márton et al, 2005).…”

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confidence: 99%

Species Preferentiality of the Pollen Tube Attractant Derived from the Synergid Cell ofTorenia fournieri

et al. 2006

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The synergid cell of Torenia fournieri attracts pollen tubes by a diffusible but yet unknown chemical attractant. Here we investigated the species difference of the attractant using five closely related species in two genera, namely T. fournieri, Torenia baillonii, Torenia concolor, Lindernia (Vandellia) crustacea, and Lindernia micrantha. These five species have an exserted embryo sac, and ablation experiments confirmed that their synergid cells attracted the pollen tube. When ovules of T. fournieri and one of the other species were cultivated together with pollen tubes of each species, pollen tubes were significantly more attracted to synergid cells of the corresponding species. The attraction was not affected by the close proximity of embryo sacs of different species. This suggests that the attractant is a species-preferential molecule that is likely synthesized in the synergid cell. The calcium ion, long considered a potential attractant, could not serve as the sole attractant in these species, because elevation of the calcium ion concentration did not affect the observed attraction. In vivo crossing experiments also showed that the attraction of the pollen tube to the embryo sac was impaired when pollen tubes of different species arrived around the embryo sac, suggesting that the species preferentiality of the attractant may serve as a reproductive barrier in the final step of directional control of the pollen tube.

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“…Calcium has been proposed to be a guidance signal because it can attract pollen tubes in vitro in some species Machlis, 1962, 1964;Reger et al, 1992), is present in high concentrations in synergid cells (Jensen, 1965;Chaubal and Reger, 1990, 1992a, 1992bTian and Russell, 1997), and is necessary for pollen tube growth (Pierson et al, 1994(Pierson et al, , 1996Holdaway-Clarke et al, 1997;Li et al, 1999). However, the addition of calcium to the medium in the in vitro T. fournieri system does not affect pollen tube attraction, indicating that calcium is not a universal attractant (Higashiyama, 2002;Higashiyama et al, 2003).…”

Section: Pollen Tube Guidancementioning

confidence: 99%