Hewelt A, Prinsen E, Thomas M, Van Onckelen H, Meins F
Friedrich Miescher Institute, Novartis Research Foundation, Basel, Switzerland.
Planta. 2000 May;210(6):884-9. doi: 10.1007/s004250050693.
The ectopic expression of knotted homologues has cytokinin-like effects on plant morphology. The functional relationship between knotted and cytokinins was investigated in cultures of leaf tissue established from tobacco (Nicotiana tabacum L. cv. Havana 425) plants transformed with the maize knotted1 (kn1) gene regulated by cauliflower mosaic virus 35S RNA expression signals. In contrast to leaf tissues of untransformed plants, leaf tissues of kn1 transformants were capable of sustained, cytokinin-autotrophic growth on auxin-containing medium and resembled the tobacco cytokinin-autotrophic mutants Hl-1 and Hl-2. The concentration of 18 cytokinins was measured in cultures initiated from leaves of three independent kn1 transformants and the Hl-1 and Hl-2 mutants. Although cytokinin contents were variable, the content of several cytokinins in Kn1, Hl-1 and Hl-2 tissue lines was at least 10-fold higher than that of wild-type tobacco tissues and in the range reported for other cytokinin-autotrophic tobacco tissues. These results suggest that the cytokinin-autotrophic growth of Kn1 lines could result from elevated steady-state levels of cytokinins.
同源异型结蛋白的异位表达对植物形态具有类似细胞分裂素的作用。利用受花椰菜花叶病毒35S RNA表达信号调控的玉米结瘤1（kn1）基因转化烟草（Nicotiana tabacum L. cv. Havana 425）植株，从其叶片组织培养物中研究了结瘤蛋白与细胞分裂素之间的功能关系。与未转化植株的叶片组织不同，kn1转化体的叶片组织能够在含生长素的培养基上持续进行细胞分裂素自养生长，类似于烟草细胞分裂素自养突变体Hl-1和Hl-2。测定了来自三个独立的kn1转化体以及Hl-1和Hl-2突变体叶片起始培养物中18种细胞分裂素的浓度。尽管细胞分裂素含量存在差异，但Kn1、Hl-1和Hl-2组织系中几种细胞分裂素的含量至少比野生型烟草组织高10倍，且处于其他细胞分裂素自养烟草组织报道的范围内。这些结果表明，Kn1系的细胞分裂素自养生长可能是由于细胞分裂素稳态水平升高所致。
