超大型烟草突变株再生植株高度是野生型的2.2倍,叶片数是野生型的3.3倍,呈现晚花发育特征;叶片气孔保卫细胞中叶绿体数是野生型的1.3倍,叶绿素a、b和叶绿素总量均高于野生型,可溶性蛋白质含量是野生型的1.18倍,过氧化物酶、细胞色素氧化酶同工酶电泳图谱上有一定差异;可溶性蛋白SDS-PAGE电泳图谱上比野生型少4条谱带;RAPD结果表明突变体在DNA水平上确实发生了变化,DDRT-PCR结果显示出两者在基因表达上有差异.突变株再生植株可以开花结实,植株高大、叶数多,晚花的特征可以稳定遗传.%A new gigantic late-flowering tobacco mutant was isolated in tobacco field in Xunyang county, Shaanxi province, in 2001. It was rescued through tissue culture and a large amount of regenerated plantlets were obtained.The results of the comparison between the regenerated plants from this mutant and the wild type plant (K346)were as follows: (1) Morphological observation showed that the leaf number of the mutant was 3.3 times as many as that of the wild type, the height of mutant was 2.2folds that of the wild type, and the mutant had the lateflowering character. (2) Cytological examination showed that the mutant was a normal diploid, and the number of chloroplasts in a guard cell of mutant was 1.3 times that of the wild type. (3) Both chlorophyll a and b content of the mutant were larger than that of the wild type; soluble protein content of the mutant was 1.18 times as much as that of the wild type. Peroxidase isozyme and cytochrome-oxidase isozyme electrophoresis analyses indicated differences between the mutant and the wild type.The soluble protein SDS-PAGE patterns showed the absence of four bands [P1 (114.6 kD), P2 (103 kD), P3(66.2 kD), P4 (24 kD)] in the mutant. (4) RAPD analysis showed that the similarity index of the mutant and the wild type was 0.612. This suggested that there were changes at DNA level. The mRNA of mutant leaves at flowering stage was isolated; DDRT-PCR was carried out using 10 random primers, using OligodT15M (M=A/G/C) as anchor primer. It has been proved that gene expression at anthesis was different between the mutant and the wild type. (5) Genetic observation showed that the mutant was homozygotic and bred true. And the mutant was a late-flowering one.
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