UV-B辐射对南方红豆杉生活史型和紫杉烷类含量的影响

Effects of supplementary UV-B radiation on life cycle forms and the accumulation of taxanes of Taxus chinensis var.mairei

运用植物生活史型的理论与方法,研究了UV-B辐射增强对南方红豆杉Taxus chinensis var.mairei表型性状和紫杉烷类次生代谢产物的影响。结果表明,随UV-B辐射强度增加,南方红豆杉无性生殖表型性状(C)明显增强(z值由0.18增加到0.52),营养生长表型性状(V)相应降低(x值由0.82降低至0.48);3.25μW.cm-.2nm-1UV-B辐射处理较对照组和9.76μW.cm-.2nm-1UV-B辐射处理组生物量增量更高;增补UV-B辐射处理显著促进了南方红豆杉叶片中紫杉醇(Taxol)的积累,但对10-去乙酰基巴卡亭Ⅲ(10-deacetylbaccatinⅢ,10-DAB)、7-木糖-10-去乙酰基紫杉醇(7-xylosyl-10-deacetyltaxol,7-xyl-10-DAT)有一定的抑制效应,其中3.25μW.cm-.2nm-1UV-B辐射处理对紫杉醇诱导效果最为明显。结果表明,在南方红豆杉田间栽培中应注意上层树种搭配、修剪,从而形成适当的UV-B辐射胁迫以诱导紫杉醇含量及生物量增量,达到高产、优质的生态培植目标。

Based on the theory of plant life history form,the present study explored the effects of supplemented UV-B radiation on phenotypic characteristics and taxane contents of Taxus chinensis var.mairei.The ecological adaptability of taxane accumulation to UV-B was studied in biennial-potted seedlings.The UV-B supplemented treatments were CK（＋0μW · cm-2 · nm-1,control）,T1 treatment（＋3.25μW · cm-2 · nm-1）,T2 treatment（＋9.76μW · cm-2 · nm-1）,respectively,under greenhouse conditions.The results showed that with increased intensity of UV-B radiation,seedling clone growth（C type） properties,e.g.number of shoots and branches,branch length,and height of shoot and branch of cloning,were all enhanced.In this occasion,the z value of the C parameter increased from 0.18 to 0.52,while the vegetative growth value（V） dropped from 0.82 to 0.48.At the same time,other phenotypic characteristics of vegetative growth were likewise reduced,including plant height,stem base diameter and biomass accumulation.Under exposure of 3.25μW · cm-2 · nm-1 UV-B radiation（T2 treatment）,individual biomass,the branch length of second level,the leaf length and leaf area were all higher than in control or T1 treatment,respectively.Moreover,the supplemental UV-B radiation significantly promoted the accumulation of taxol（P0.05）,especially for the T1 treatment,while the accumulation of 10-deacetylbaccatin III（10-DAB）,7-xylosyl-10-deacetyltaxol and 7-xyl-10-DAT was inhibited to different extent.The content of taxol was highest under 3.25μW · cm-2 · nm-1UV-B radiation. In this experiment,although the young plants of T.chinensis var.mairei grew under the woods and natural conditions,they still revealed adaptability to UV-B exposure.Moreover,the low level UV-B radiation could initiate the settlement ability of young seedlings of T.chinensis var.maire to clone growth.The height of plants dropped,however,main harvest position like branch shoot length,leaf area and biomass of single plants all increased.As a result,the plant displayed a VC life history form and the content of taxol also increased,taxol being the main bioactive substance.Consequently,it can be confirmed that some plants enhance their content and output of bioactive substance when switched from V form to VC life history form.Thus,for field cultivation of T.chinensis var.mairei,attention should be paid to i） match of tree species,ii） trim of upper layer,and iii） the relationship between life history form of and taxol content.The parameter of life history form can be used as the main indicator to adjust the intensity of photopermeability,with the aim to optimize UV-B exposure for increasing taxol content,biomass,high yield and good quality. In conclusion,the present study confirmed that the yield of bioactive substance increased when plant life history form was switched from V to VC.