干旱和UV-B辐射胁迫及其互作对白沙蒿抗性生理的影响

以白沙蒿为试验材料，在干旱（D）、UV-B辐射（U）和干旱与UV-B辐射复合（D+U）胁迫下，从幼苗生长、膜脂氧化、次生物质类黄酮、脂肪酸代谢及其基因表达等方面研究了干旱和UV-B辐射胁迫及其互作对白沙蒿抗性生理的影响。结果显示，D和U处理下，白沙蒿幼苗叶、茎、根生物量及总生物量积累减少，株高、叶面积和相对含水量（RWC）降低。D+U处理缓解了D和U处理造成的白沙蒿生物量的下降。D和U处理下，叶相对电导率（REC）显著升高；D+U处理的REC显著下降。D处理的丙二醛（MDA）含量和脂氧合酶（LOX）活性分别为对照（CK）的1.65和3.69倍，而U处理MDA含量和LOX活性无显著变化；D+U处理MDA含量和LOX活性分别为D处理的66.69%和44.00%。D和U处理类黄酮含量分别为CK的1.25和1.37倍；D+U处理类黄酮含量为D处理的1.57倍。D处理未引起不饱和脂肪酸指数（IUFA）显著变化，U处理造成IUFA显著降低，为CK的91.96%；D+U处理IUFA为U处理的1.08倍。结果表明，干旱和UV-B辐射胁迫引起的膜损伤是造成白沙蒿生物量下降的主要原因；干旱和UV-B辐射复合胁迫通过增加类黄酮含量、抑制LOX活性和提高脂肪酸不饱和度的效应产生叠加作用，缓解了彼此对白沙蒿造成的膜损伤。

Interactive effects of drought and UV-B radiation on physiological defences in Artemisia sphaerocephala

This research explored the physiological effects of drought （D）， UV-B radiation stress （U） and their interactions （D+U） on Artemisia sphaerocephala and its stress tolerance. The seedling growth， membrane lipid oxidation， flavonoid metabolism， fatty acid metabolism and FAD gene expression in A. sphaerocephala were studied under D， U， and D+U， and unstressed （CK） treatments. In D and UV treatments， leaf weight， stem weight， root weight， total biomass， plant height， leaf area and relative water content were decreased， compared to CK. For the D+UV treatment， biomass reductions were less than those observed in D or UV treatments applied alone. Compared to CK， relative electric conductivity increased significantly in both D and UV treatments， but decreased significantly in the D+UV treatment. Malondialdehyde （MDA） content and lipoxygenase （LOX） activity in the D treatment were， respectively， 1.65 and 3.69 times those in the control treatment （CK）， while MDA content and LOX activity in the UV treatment showed no significant change. MDA content and LOX activity in the D+UV treatment were， respectively， 66.69% and 44.00% of those in the D treatment. Flavonoid content in D and UV treatments was， respectively， 1.25 and 1.37 times that in CK. Flavonoid content in the D+UV treatment was 1.57 times that in the D treatment. An index of unsaturated fatty acid （IUFA） in the D treatment showed no significant change， while IUFA in the UV treatment were 91.96% of that in CK. IUFA in the D+UV treatment was 1.08 times of that in UV treatment. These results indicate： An important reason for the stress-induced biomass decline in A. sphaerocephala was that drought and UV-B radiation caused membrane damage； The combined stress of drought and UV-B radiation inhibited LOX activity by increasing flavonoid content and increased unsaturated fatty acids， which alleviated the membrane damage caused by drought and UV-B radiation in A. sphaerocephala.