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Summary Chemical analysis of each individual leaf of fivePlantago lanceolata (Plantaginaceae) plants showed that iridoid glycoside content increased from undetectable in the oldest photosynthetic leaves to over 9% dry weight in the youngest leaves. The relative proportion of the two iridoid glycosides inP. lanceolata also changed with leaf age: older leaves had significantly more aucubin, whereas the youngest leaves had primarily or solely catalpol. Oviposition tests with femaleJunonia coenia (Nymphalidae) butterflies, showed that they laid most of their eggs on new leaves. 相似文献
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Summary. Many secondary plant compounds are involved in defense against both insect herbivores and pathogens. Two secondary plant
compounds of Plantago lanceolata, the iridoid glycosides catalpol and its precursor aucubin, are well known for their deterrent effects on generalist and
non-adapted specialist insect herbivores. We tested the effects of these compounds on the in-vitro growth of a specialist
and generalist fungal pathogen of this host species. Two chemical forms of these iridoids were tested. The glycosides and
their aglycones, the products of enzymatic conversion by specific $/Beta$-glucosidase enzymes. The glycosides enhanced growth
of both the specialist fungus Diaporthe adunca and the generalist fungus Fusarium moniliforme var. subglutinans. The positive effect of these glycosides on the generalist fungus is in sharp contrast with the generally negative effects
of these glysosides on generalist insect herbivores. The aglycones of aucubin and catalpol reduced the growth of the specialist
fungus D. adunca, but, contrary to expectation, enhanced the growth of the generalist fungus F. moniliforme var. subglutinans. Effects of aucubin on D. adunca were stronger than effects of catalpol. This was true both for the growth stimulating effects of the glycosides and for the
fungitoxic effects of the aglycones. We therefore expect that the effects of these iridoids in P. lanceolata on the specialist fungus will strongly depend on the ratio between catalpol and its precursor aucubin and the chemical form
(glycoside or aglycone) in which these compounds are encountered by the fungus during growth. Our results suggest that iridoid
glycosides in P. lanceolata can be used as defense against both herbivores and pathogens, but that their effects are highly specific with respect to
the natural enemy species that is encountered.
Received 11 April 2002; accepted 9 August 2002 相似文献
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模拟酸雨对杜仲抗性生理及药用有效成分含量的影响 总被引:2,自引:0,他引:2
研究了模拟酸雨对杜仲抗性生理及药用成分绿原酸、桃叶珊瑚甙、总黄酮含量的影响.结果表明,春夏秋季在系列模拟酸雨胁迫下,杜仲叶叶液pH值、K 、Ca2 含量随酸雨pH值降低而降低,呈显著正相关;杜仲叶膜保护酶超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)和膜保护物质抗坏血酸(AsA)含量在春夏两季随酸雨pH值降低呈单峰曲线型变化,秋季则均随酸雨pH值降低而降低,且呈显著正相关;抗性物质脯氨酸(Pro)含量春夏两季随酸雨pH值降低而升高,呈显著负相关,秋季则在pH3.0和2.5的强酸雨胁迫下急剧降低;膜脂过氧化产物丙二醛(MDA)含量无论春夏秋季均与酸雨pH值呈显著负相关;春季仅pH2.5的强酸雨对杜仲叶绿原酸、桃叶珊瑚甙和总黄酮等药用成分含量影响较大,夏秋两季各药用有效成分则均随酸雨pH值降低而降低,呈显著正相关.图1表2参27 相似文献
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