高温对喜树生长及叶片喜树碱含量的影响

喜树碱是喜树(Camptotheca acuminata)的一种次生代谢物,有良好的抗肿瘤活性,在喜树体内的合成和积累受遗传和环境因子的影响。笔者在人工气候室中研究了温度对当年生喜树苗生长及叶片喜树碱合成的影响。试验设置了3种昼/夜(白天6:00至18:00,夜间18:00至次日6:00)温度处理,分别为30 ℃/25℃(T1)、35 ℃/30 ℃(T2)和40 ℃/35 ℃(T3)。结果表明:T3温度条件下,喜树有最高的生物量,T2处理有利于喜树苗高和地径的生长,而T3处理则有利于喜树根和茎的生物量积累。T2处理促进了喜树叶片内可溶性糖的积累,降低了可溶性蛋白质的含量,而T1和T3处理则提高了叶片色氨酸脱羧酶(TDC)的活性; T2处理下喜树碱含量和单株叶片喜树碱产量最高。试验期间喜树碱含量(产量)的变化趋势与TDC活性的变化不一致。综合认为,适宜的温度条件(T2)有利于喜树体内喜树碱的生物合成与积累,喜树碱在喜树体内的生物合成和积累是多种因素综合作用的结果。

Effects of temperature on the growth and camptothecin contents of Camptotheca acuminata

Camptothecin(CPT)is an important secondary metabolite in Camptotheca acuminata, and it can be used as an anticancer drug. The biosynthesis and accumulation of CPT in C. acuminata are affected by heredity and environment. In this paper, the effect of temperature on the growth and CPT biosynthesis of one year old C. acuminata was studied in phytotron. Three temperature day/night(day time 6:00-18:00,night time18:00-6:00), 30 ℃/25 ℃(T1), 35 ℃/30 ℃(T2)and 40 ℃/30 ℃(T3)were designed. We found that C. acuminata presented the highest biomass at T3, and T2 was beneficial to the height and caliper of seedlings, and T3 was favorable to the accumulation of stem and root biomass. T2 treatment presented the highest soluble sugar content, but the lowest soluble protein content and the activity of tryptophan decarboxylas(TDC). At T2 condition, the highest CPT content and CPT yield per plant in the leaves were observed. The changing regulation of CPT content was not in accordance with the activity of TDC. So appropriate temperature T2 is very important to the biosynthesis and accumulation of CPT, and the biosynthesis and accumulation of CPT is a comprehensive result of enzymes and environmental factors.