Enhancement of Regeneration in Rice Tissue Cultures by Water and Salt Stress

Abstract

Studies of rice tissue culture and plant regeneration have increased recently, but some problem areas remain. Many reports have stated that genotypes and explant sources are important parameters in determining the success of rice plant regeneration after culture (Maeda 1967; Wernicke et al. 1981; Abe and Sasahara 1982; Lai and Liu 1982, 1986; Liu and Lai 1982; Ling et al. 1983; Heyser et al. 1983; Fatokun and Yamada 1984; Abe and Futsuhara 1984, 1986); but there is little discussion about what causes the differences of genotypes in regenerative ability and whether the poorly regenerating callus can be changed into vigorously regenerating callus. Another problem is that even high regenerative ability is lost very rapidly after subculture (Henke et al. 1978; Inoue and Maeda 1980; Heyser et al. 1983; Abe and Futsuhara 1985; Lai and Liu 1986). Several methods have been tried for maintaining and increasing the rate of regeneration. Many studies have been conducted on the effect of exogenous phytohormones (Yamada et al. 1967; Saka and Maeda 1969; Nishi et al. 1973; Henke et al. 1978; Cornejo-Martin et al. 1979; Inoue and Maeda 1980; Heyser et al. 1983). Some indicated that the medium should be enriched with yeast extract (Yatazawa et al. 1967), or certain amino acids, such as tryptophan (Siriwardana and Nabors 1983). It has also been suggested that the regenerable calli be carefully separated from unregenerable ones and transferred to fresh medium during each subculture (Heyser et al. 1983).