弱光对长春花（Catharanthus roseus）幼苗中可溶性糖、生物碱及激素含量的影响

阐述了低光照强度和正常光照条件下长春花（Catharanthus roseus）幼苗叶片中可溶性糖、生物碱及内源激素等几种生理活性物质含量的动态变化，以揭示弱光胁迫对长春花生理代谢的影响及上述生理代谢对植物适应弱光环境的生态学意义。结果显示，弱光培养提高了长春花在自身支撑结构的投入，如叶柄长和节间长都显著增加，同时抑制了有性生殖。在弱光培养的第1周，长春花叶片中果糖（fructose，Fru）、葡萄糖（glucose，Glc）和蔗糖（sucrose，Suc）的含量分别由处理前的（0．62±0．01），（1．86±0．12），（0．24±0．01）mg／g FW下降为（0．38±0．02），（0．60±0．03），（0．17±0．02）mg／g FW，均显著低于对照（P〈0．01），表明碳同化水平下降。长春花叶片中文朵灵（vindoline，VIN）和长春质碱（catharanthine，CAT）含量在弱光条件下呈显著增加趋势，处理结束时是对照的3倍左右，而它们的耦合产物长春碱（vinblastine，VLB）合成和积累受到抑制，其含量在第3周时仅为对照的50％。弱光条件处理前2周促进了长春花叶片中脱落酸（abscisic acid，ABA）、赤霉素（gibberelline，GA3）和吲哚乙酸（indole-3-acetic acid，IAA）含量水平的积累。这些结果表明，在弱光条件下长春花幼苗的上述生理代谢都发生着显著的变化，可能在植物适应弱光胁迫过程中发挥着积极的调控作用。

Effects of low light intensity on changes of soluble sugars, alkaloids and phytohormones in Catharanthus roseus seedlings

The variations of soluble sugars, alkaloids and phytohormones contents in leaves of Catharanthus roseus seedling subjected to low light intensity (LL) and normal light (NL) condition were investigated in this paper. The purpose was to elucidate the effects of LL on soluble sugars, alkaloids and phytohormones of C. roseus and the possible roles of these physiological metabolisms played during acclimation to LL. Leafstalk and node length were significantly increased upon LL exposure, while the lower energy percent were allocated to sexual reproduction. In the first week, the concentrations of fructose (Fru), glucose (Glc) and sucrose (Suc) significantly deceased under LL from (0.62±0.01), (1.86±0.12), (0.24±0.01) mg/g FW to (0.38±0.02), (0.60±0.03), (0.17±0.02) mg/g FW, respectively. This may be related to decreased level of assimilation of leaves under LL. The accumulation of vindoline (VIN) and catharanthine (CAT) contents in leaves elevated after LL exposure up to threefold compared to control at the end of treatment. At the same time, however, the content of the anticancer compound vinblastine (VLB) generated by its precursors VIN and CAT decreased to 50% of the control. In the first two weeks, the contents of abscisic acid (ABA), gibberelline (GA3) and indole-3-acetic acid (IAA) in C. roseus leaves were enhanced. This result may be related to the rapid increasing of plant nodes and leafstalk length. In conclusion, these results indicate that the acclimations of plants to LL were positively regulated by physiological metabolisms. This may have important implications for the production of the anticancer drug VLB in plantations and greenhouses at an industrial scale.