Localization of the Ca2+-binding protein, Bra r 1, in anthers and pollen tubes

Takashi Okada, Zhaojie Zhang, Scott D. Russell, Kinya Toriyama

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24 Citations (Scopus)


Calcium plays an essential role during pollen development and pollen tube growth, and several Ca2+-binding proteins are expressed in anthers. We have previously reported that Brassica pollen allergens encoded by Bra r 1 and Bra r 2 show sequence similarities to Ca2+-binding proteins [Toriyama et al. (1995) Plant Mol. Biol. 29: 1157]. Herein, we report that both genes are expressed in the diploid tapetum and haploid microspores, as detected by in situ RNA hybridization. Immunoblot analysis revealed that Bra r 1 and Bra r 2 were accumulated in anthers during pollen development. When pollen grains were suspended in an aqueous solution, both proteins were mainly detected in the pollen extracellular fraction, indicating that Bra r 1 and Bra r 2 are released from the pollen upon hydration. Localization of Bra r 1 was further investigated in sections of anthers and pollen tubes. Bra r 1 was detected in the tapetum, microspores and pollen grains. In longitudinal sections of cross-pollinated pistils, Bra r 1 was detected throughout pollen tubes elongating in transmitting-tissue. These findings suggest that Bra r 1 may be involved in pollen-pistil interaction and pollen tube growth.

Original languageEnglish
Pages (from-to)1243-1252
Number of pages10
JournalPlant and Cell Physiology
Issue number12
Publication statusPublished - 1999


  • Ca-binding protein
  • Calcium
  • Immuno-localization
  • Pollen allergen
  • Pollen tube growth

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology


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