title: Calreticulin expression and localization in plant cells during pollen-pistil interactions.
abstract: In this report, the distributions of calreticulin (CRT) and its transcripts in Haemanthus pollen, pollen tubes, and somatic cells of the hollow pistil were studied. Immunoblot analysis of protein extracts from mature anthers, dry and germinated pollen, growing pollen tubes, and unpollinated/pollinated pistils revealed a strong expression of CRT. Both in vitro and in situ studies confirmed the presence of CRT mRNA and protein in pollen/pollen tubes and somatic cells of the pistil transmitting tract. The co-localization of these molecules in ER of these cells suggests that the rough ER is a site of CRT translation. In the pistil, accumulation of the protein in pollen tubes, transmitting tract epidermis (tte), and micropylar cells of the ovule (mc) was correlated with the increased level of exchangeable calcium. Therefore, CRT as a Ca(2+)-binding/buffering protein, may be involved in mechanism of regulation calcium homeostasis in these cells. The functional role of the protein in pollen-pistil interactions, apart from its postulated function in cellular Ca(2+) homeostasis, is discussed.
authors.affiliation: Laboratory of Developmental Biology, Nicolaus Copernicus University, Gagarina 9, 87-100, Toruń, Poland. mlenart@umk.pl
authors.forename: Marta
authors.initials: M
authors.lastname: Lenartowska
authors.forename: Robert
authors.initials: R
authors.lastname: Lenartowski
authors.forename: Dariusz Jan
authors.initials: DJ
authors.lastname: Smoliński
authors.forename: Bogdan
authors.initials: B
authors.lastname: Wróbel
authors.forename: Janusz
authors.initials: J
authors.lastname: Niedojadło
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Jaworski
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Bednarska
mesh_terms: D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D037282:Calreticulin / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D018506:Gene Expression Regulation, Plant; D005936:Glucans / Q000378:metabolism; D019668:Liliaceae / Q000166:cytology* / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D031425:Plasmodesmata / Q000378:metabolism / Q000648:ultrastructure; D011058:Pollen / Q000166:cytology* / Q000378:metabolism* / Q000648:ultrastructure; D053205:Pollen Tube / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D054817:Pollination; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D037282:Calreticulin; D005936:Glucans; D012333:RNA, Messenger; C048306:callose; D002118:Calcium