COMPARATIVE STUDIES ON IN-VITRO RESPONSE OF FRESH AND OLD CALLI OF RICE (Oryza sativa L.)

Abstract

In-vitro responses of fresh and old calli of japonica variety, Taipei 309, and indica variety, Qiuguiai 11, were investigated with different culture procedures to develop an efficient protocol to improve the regeneration efficiency of long-term cultured calli of rice. Pre-culture media were used to restore the declined plant regeneration ability in long-term cultured calli. Both proliferation rates and regeneration efficiencies were compared between 2 varieties with fresh and old calli before and after using pre-culture media. It was clear that in-vitro culture responses were being declined after the second subculture of calli, indicating the loss of abilities to regenerate plants from long-term cultured calli in rice. An efficient protocol developed in this study with a pre-culture medium containing 10 mg/l BA,4 mg/l ABA, 1 mg/l NAA and 3% maltose showed 7-9 folds increase of in-vitro responses in longterm cultured old calli. This protocol not only restored the declined in-vitro ability, but also reduced the somaclonal variation, especially in indica variety, Qiuguiai 11. Furthermore, japonica variety, Taipei 309, performed well in the proliferation cultures before and after using pre-culture media, showing higher proliferation rates with both fresh and old calli, comparing with indica variety, Qiuguiai 11. Higher regeneration efficiencies with less number of albino plants were given by indica variety, Qiuguiai 11 throughout the study. This study clearly indicates that the invitro culture responses in rice depend mainly on the varieties of different subspecies, culture conditions and compositions, and the stages of the culture procedures.