Journal Article

Cloning of cDNA Encoding NtEPc, a Marker Protein for the Embryogenic Dedifferentiation of Immature Tobacco Pollen Grains Cultured in Vitro

Masaharu Kyo, Hiroaki Miyatake, Kouki Mamezuka and Ken Amagata

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 41, issue 2, pages 129-137
Published in print February 2000 | ISSN: 0032-0781
Published online February 2000 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/41.2.129
Cloning of cDNA Encoding NtEPc, a Marker Protein for the Embryogenic Dedifferentiation of Immature Tobacco Pollen Grains Cultured in Vitro

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We partially purified three Nicotiana tabacum L. embryogenic pollen-abundant phosphoproteins (NtEPa to c) which appeared in the cells undergoing a dedifferentiation process from immature pollen grains to embryogenic cells, caused by glutamine-deficiency in vitro. All the NtEPs had a highly conserved N-terminal amino acid sequence. Using degenerate oligonucleotide probes designed from the amino acid sequences, the cDNA for NtEPc was isolated from a cDNA library of pollen cultured in glutamine-free medium. The cDNA sequence showed moderate homology with several type-1 copper-binding glycoproteins and with a kind of early nodulin though its function could not be predicted. Expression analysis revealed that the level of mRNA for NtEPc was high during the dedifferentiation and also in the very early period of pollen embryogenesis but it was low in the developmental process of microspores/pollen in anthers, in the in vitro maturation process and both in the stational and logarithmic growth phases of tobacco BY-2 cells. Furthermore, an acidic medium pH, which promoted the induction of dedifferentiation increased the level of mRNA for NtEPc, whereas the presence of 6-benzylaminopurine, which inhibited it, decreased the level. These results suggest that the expression of NtEPc gene is correlated with the dedifferentiation but not with pollen development or cell division.

Keywords: cDNA cloning; Dedifferentiation; Nicotiana tabacum L; Phosphoproteins; Pollen embryogenesis; Protein purification

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Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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