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

摘要： 以盐粳2号脱壳种子为外植体研究了培养基不同浓度琼脂对愈伤组织植株再生率的影响及可能的机理。在分别进行脱分化、分化和继代培养基中琼脂浓度试验时，当琼脂从0.5％提高到1.0％ 植株再生率均显著升高。在继代和分化培养基琼脂浓度均为1.0%时植株再生率最高，而脱分化培养基0.5%或1.0%琼脂和分化培养基1.0%琼脂 组合，再生率最高，两者均为1.0% 琼脂反而降低。试验还表明，随着培养基中琼脂浓度提高，愈伤组织含水量显著降低而脯氨酸含量上升。较高浓度（1.0%）琼脂继代培养的愈伤组织内源ABA含量显著高于较低浓度（0.5%）琼脂的，而ZRs含量则显著较低。同样，在分化培养过程中，较高浓度琼脂分化培养的愈伤组织内源ABA含量显著地高于较低琼脂的，而ZRs含量则相反，但差异不显著。 V 关键词：琼脂浓度：精

关键词: 琼脂, 植株再生率, 水稻, 愈伤组织, 激素