Abstract
In pollen culture methods developed for Nicotiana rustica and N. tabacum, it is possible to induce embryogenic dedifferentiation, i.e., transformation process from immature pollen to embryogenic cells. As biochemical markers for the dedifferentiation of pollen attention has been focused on several phosphoproteins which characteristically appeared in the two-dimensional gel electrophoretogram of total protein from pollen fed with 32Pi in both species. Here, the six phosphoproteins of N. rustica, NrEP1 to 6, were partially purified and their N-terminal amino acid sequences were identified. The sequences were similar to each other and also to those of the phosphoproteins (NtEPs) previously identified in N. tabacum. This suggests that a protein family possessing a common structure plays an important role in the induction process of pollen embryogenesis in Nicotiana.