赤霉素调控木质部发育的细胞学研究

Cytological study of gibberellin regulated xylem development

以烟草为材料,通过转基因技术与外源施用激素,获得了超表达PtGA20ox、PtGA2ox1及NtGA20ox RNAi转基因植株及不同激素处理野生型烟草植株,并对这些植株茎部木质部进行了石蜡切片及显微观察。结果表明:提高内源赤霉素(GA)水平或外源施用GA3能够明显促进烟草节间快速伸长,并促使木质部形成提前,木质部分化程度提高;降低内源GA水平或外源施用GA合成抑制剂PAC则延缓木质部的发育。研究结果证明了GA在木质部发育过程中起到正向调控作用,且存在依赖GA浓度的调控机制;生长素IAA对木质部发育的正向调控作用至少部分是通过促进GA的合成实现的。

We conducted the studies on xylem development of tobacco stem by over-expressed PtGA2Oox and PtGA2oxl genes, NtGA2Oox RNAi transgenic lines and added extra different hormones with paraffin-cut section method and microscopic observation. The results showed that rapid elongation of internodes as well as xylem formation and development were stimulated by increasing endogenous gibberellins （GAs） levels or exogenous application of GA3 , while xylem growth was delayed by decreasing endogenous GAs levels or exogenous application of PAC （GAs biosynthetic inhibitor）. Thus our experiment proved that GAs played positive regulatory roles in the development process of xylem and this happened through a GAs concentration-dependent mechanism. Besides, we proved that the positive effects of IAA on xylem development were realized through increasing the level of GAs syntheses at least in some degree.