Hydroxy-L-Proline-Resistant Mutants in Rice

Abstract

Mutants resistant to chemical stress such as antibiotics, amino acid analogs, and phytotoxins, are considered to be excellent materials for research on plant cell genetics. To obtain such mutants, it has been shown that selection of mutants in vitro is a very efficient method, because large cell populations can be screened easily and the cell culture itself produces genetical variability (Larkin and Scowcroft 1981; Sun et al. 1983; Oono 1984). However, there are some problems in the cell culture method to maintain the mutant cell lines or to obtain whole plant mutants: the regenerative capacity of cultured cells is lost with increasing time in culture (Widholm 1977), instability in the chromosome number is frequently observed in cultured cells or regenerated plants (Karp et al. 1982), and variant traits selected from the cultured cells are not always expressed in the whole plants (Kool 1982; Miflin et al. 1983). An alternative method, the selection of mutants from mutagenized population, has been proposed as a practical method for establishing a genetic marker useful both in the whole plant system and in the cultured cell system (Hasegawa and Inoue 1983; Miflin et al. 1983).