超大型烟草突变株的生理生化特征和分子生物学鉴定

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。

Physiological and Biochemical Characteristics and Molecular-Biological Identification of a Gigantic Tobacco Mutant

A new gigantic late-flowering tobacco mutantwas isolated in tobacco field in Xunyang county, Shaanxiprovince, in 2001. It was rescued through tissue cultureand a large amount of regenerated plantlets were obtained.The results of the comparison between the regeneratedplants from this mutant and the wild type plant (K346)were as follows: (1) Morphological observation showedthat the leaf number of the mutant was 3.3 times as manyas that of the wild type, the height of mutant was 2.2folds that of the wild type, and the mutant had the late-flowering character. (2) Cytological examination showedthat the mutant was a normal diploid, and the number ofchloroplasts in a guard cell of mutant was 1.3 times thatof the wild type. (3) Both chlorophyll a and b content ofthe mutant were larger than that of the wild type; solubleprotein content of the mutant was 1.18 times as much asthat of the wild type. Peroxidase isozyme and cyto-chrome-oxidase isozyme electrophoresis analyses indi-cated differences between the mutant and the wild type.The soluble protein SDS-PAGE patterns showed the ab-sence of four bands [P1 (114.6 kD), P2 (103 kD), P3(66.2 kD), P4 (24 kD)] in the mutant. (4) RAPD analysisshowed that the similarity index of the mutant and thewild type was 0.612. This suggested that there werechanges at DNA level. The mRNA of mutant leaves atflowering stage was isolated; DDRT-PCR was carriedout using 10 random primers, using OligodT15M (M=A/G/C) as anchor primer. It has been proved that gene ex-pression at anthesis was different between the mutant andthe wild type. (5) Genetic observation showed that themutant was homozygotic and bred true. And the mutantwas a late-flowering one.