Summary
Using energy-dispersive X-ray microanalysis of mature, unpollinated wheat ovaries fixed by freeze-substitution, we show here that the synergid cells store a relatively high concentration of calcium. Based on our results and other indirect evidence, we suggest that supraoptimal levels of calcium in synergids may regulate: (1) correct orientation of the pollen tube, by forming a calcium gradient in the vicinity of the synergids, and (2) arrest and rupture of the pollen tube to release the sperm near the egg.
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Chaubal, R., Reger, B.J. Relatively high calcium is localized in synergid cells of wheat ovaries. Sexual Plant Reprod 3, 98–102 (1990). https://doi.org/10.1007/BF00198852
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DOI: https://doi.org/10.1007/BF00198852