关键词: 琼脂, 植株再生率, 水稻, 愈伤组织, 激素

Abstract: Eftects of agar concentration in dedifferentiation, differentiation, and subculture media and in their combinations on the rate of plantlet regeneration were investigated in calli from mature seeds of rice cv. Yanjing 2. Optimal agar concentration in dedifferentiation, differentiation, and subculture media were 1.0% used in respective experiments when 0.5% agar in other one or two media were given. The effect was significant in combination of 1.0% agar in both subculture and differentiation media and in combination of 0.5% or 0.75% in dedifferentiation medium with 1.0% agar in differentiation medium while it was not significant in combination of 1.0% in both dedifferentiation and differentiation media for plantlet regeneration. Agar concentration affected water availability in calli, i. e. higher agar (1.0%) in medium limited water absorption of calli and made calli drier. The water content was reduced and proline level increased as agar concentration increased. Phytohormones play an important role in plantlet regeneration in vitro. Agar concentration greatly modified contents of endogenous hormones of calli. With increase of agar concentration in subculture medium, the rate of plantlet regeneration of endogenous ABA were increased while that of endogenous ZRs decreased. It is suggested that mechanism for improving the rate of plantlet regeneration with higher agar concentration in rice calli may resulted from the reduction of water content, which caused water stress in terms of the increase of proline content, followed by the regulation of the contents of endogenous ABA and ZRs, and finally improved the rate of plantlet regeneration.

Key words: Agar concentration: Endogenous ABA content: Endogenous ZRs content, The rate of plantlet regeneration, Rice calli