Adaptations of the floral characteristics and biomass allocation patterns of Gentiana hexaphylla to the altitudinal gradient of the eastern Qinghai-Tibet Plateau

This study addressed the floral component traits and biomass allocation patterns of Gentiana hexaphylla as well as the relationships of these parameters along an elevation gradient(approximately 3700 m, 3800 m, 3900 m, and 4000 m) on the eastern Qinghai-Tibet Plateau. The plant height, floral characteristics, and biomass allocation of G. hexaphylla were measured at different altitudes after field sampling, sorting, and drying. Plant height was significantly greater at 3700 m than that at other elevations. Flower length was significantly greater at 4000 m than that at other elevations, whereas the flower length at low elevations showed no significant differences. Corolla diameter increased with altitude, although the difference was not significant between 3800 m and 3900 m. Variations in biomass accumulation, including the aboveground, photosynthetic organ, flower and belowground biomasses, showed non-linear responses to changes in altitude. The aboveground and photosynthetic organ biomasses reached their lowest values at 4000 m, whereas the belowground and flower biomassreached minimum values at 3700 m. The sexual reproductive allocation of G. hexaphylla also increased with altitude, with a maximum observed at 4000 m. These results suggest that external environmental factors and altitudinal gradients as well as the biomass accumulation and allocation of G. hexaphylla play crucial roles in plant traits and significantly affect the ability of this species to adapt to harsh environments. The decreased number of flowers observed at higher altitudes may indicate a compensatory response for the lack of pollinators at high elevations, which is also suggested by the deformed flower shapes at high altitudes. In addition, the individual plant biomass(i.e., plant size) had significantly effect on flower length and corolla diameter. Based on the organ biomass results, the optimal altitude for G. hexaphylla in the eastern Qinghai-Tibet Plateau is 3800 m, where the plant exhibits minimum propagule biomass and asexual reproductive allocation.

高效液相色谱法测定六叶龙胆不同部位的龙胆苦苷含量

目的采用高效液相色谱法测定六叶龙胆不同部位的龙胆苦苷含量,比较不同部位龙胆苦苷的含量。方法 CAPCELL PAK C18（250 mm×4.6 mm,5μm）色谱柱;流动相为甲醇-0.5%乙酸水溶液（25∶75）;检测波长为270 nm;流速为1.0 mL/min;柱温为32℃。结果龙胆苦苷在0.5-6.9μg范围内呈线性关系,回归方程为Y=1.2908×106X＋4.8047×104,相关系数（r）=0.9999,测定方法的平均回收率为98.56%,RSD=1.01%（n=6）。龙胆苦苷含量测量结果为：花〉根〉茎〉叶〉枯龙胆。结论本研究所采用的高效液相色谱法快速简便,准确,精密度好;六叶龙胆不同部位中龙胆苦苷含量有较大差异。

横断山地区六叶龙胆复合群的遗传分化与种群动态历史

以六叶龙胆(Gentiana hexaphylla Maximowicz ex Kusnezow)复合群的21个居群为材料,首先通过居群内关键形态性状的统计对复合群加以区分,随后以叶绿体片段trnS-trnG为分子标记,对其遗传分化与种群动态历史进行研究。结果显示:六叶龙胆复合群21个居群共鉴定出20个单倍型,居群平均单倍型多样性、核苷酸多样性和核苷酸多样性指数分别为0.444、0.00732和3.73,表现出较高的遗传多样性水平;居群间共享单倍型少,遗传变异主要发生在居群间(72.74%)。贝叶斯分析结果表明复合群内的遗传分化主要发生在近两百万年以内。歧点分布分析和中性检验结果均显示,复合群近期未经历明显的居群扩张。因此,六叶龙胆复合群的遗传分化可能是横断山地区第四纪环境与气候变化以及高山峡谷地貌的地理隔离两者共同作用的结果。

六叶龙胆化学成分研究

目的研究六叶龙胆化学成分。方法采用硅胶柱色谱、Sephadex LH-20葡聚糖凝胶柱色谱、制备液相色谱等色谱技术进行分离和纯化,通过理化方法和波谱数据分析鉴定化合物的结构。结果从六叶龙胆中分离鉴定了17个化合物,分别为:龙胆苦苷(1),獐牙菜苷(2),獐牙菜苦苷(3),三叶草苷(4),rindoside(5),rigenolides G(6),poacynose(7),vanillyl alcohol-4-O-β-D-glucopyranoside(8),isotachioside(9),tachioside(10),1,5-bis (β-D-glucopyranosyloxy-2-(3′,3′-dimethylallyl) benzene(11),松柏苷(12),5,7,3′,4′-四羟基-8-C-β-D-葡萄糖黄酮碳苷(13),牡荆素(14),丁香树脂酚葡萄糖苷(15),松脂酚-4-O-β-D吡喃葡萄糖苷(16)和腺苷(17)。其中化合物1~6为裂环环烯醚萜苷类成分,化合物7~12为苯基糖苷类衍生物,化合物13~14为黄酮类成分,化合物15~16为木脂素类成分。结论化合物1~17均为首次从该植物中分离得到。