摘要
马唐[Digitariasanguinalis(L.)Scop]生防菌画眉草弯孢霉(CurvulariaeragrostidisJ.A.Meyer)菌株QZ2000产生一种具有除草剂活性毒素α,β-dehydrocurvularin。毒素对马唐叶片类囊体膜光系统Ⅱ(PSⅡ)的电子传递有较强的抑制作用,当毒素浓度达到0.688mmol·L-1时,电子传递速率比对照降低了19.37%。毒素对PSⅠ的电子传递影响较小。叶绿素荧光动力学参数测定显示,用0.516mmol·L-1浓度的毒素处理马唐离体叶片24h后,叶片的Fv/Fo、Fv/Fm、ΦPSⅡ、qP、qN、Fm都显著降低,而Fo呈上升趋势。试验结果显示,该毒素对PSⅡ光化学活性的抑制作用与均三氮苯类除草剂阿特拉津(Atrazine)、西玛津(Simazine)和取代脲类除草剂敌草隆(Diuron)有相似之处,叶绿素荧光动力学参数的变化表明,该毒素损坏PSⅡ中心和抑制QA的再氧化。表明该毒素可能是通过损坏PSⅡ中心及抑制QA的再氧化,使PSⅡ反应中心向QA、QB电子传递受阻,从而影响马唐的光合磷酸化与碳同化,引起马唐叶片坏死。qN的显著降低,表明毒素对PSⅡ中心的损坏也可能是由于毒素导致还原型电子受体积累增加了自由基的产生所致。
Curvularia eragrostidis strain QZ2000, a potential biocontrol candidate for large crabgrass [Digitaria sanguinalis (L.) Scop], produced a mycotoxin with herbicidal activity, which was identified as α,β-dehydrocurvularin. Inhibition of photosynthetic electron transport in isolated thylakoids from large crabgrass was investigated. The electron transport activities of the photosystem II (PS II) in isolated thylakoids was significantly inhibited by the mycotoxin. At a concentration of 0.688 mmol·L-1, the electron transport rate of PS II was reduced by 19.37%. The mycotoxin had a little effect on the electron transport rate of the photosystemⅠ (PSⅠ). When the detached leaves were treated with mycotoxin (0.516 mmol·L-1) for 24 h, Fv/Fo, Fv/Fm, ΦPSⅡ, qP, qN, Fm values of large crabgrass declined significantly, but Fo values increased considerably. In the experiment, the changes of chlorophyll fluorescence parameter suggested that the mycotoxin was similar as herbicides atrazine, simazine, and diuron with inhibitory activities on the PS II, namely, the mycotoxin may damage the PS II reaction center and blocks the reoxidation of the primary electron acceptor (QA). These results indicate that the mode of action of mycotoxin might be the damage of PS II reaction center and inhibition of the reoxidation of the primary electron acceptor (QA), which resulted in the inhibition in electron transport between PS II reaction center and QA or between QA and the second electron acceptor (QB). Sequentially photophosphorylation and carbon assimilation were inhibited and metabolism of large crabgrass was disturbed. The decrease of qN value suggested that mycotoxin caused the accumulation of reductive electron acceptor and increased the production of the free radicals. This could be the cause of the damage of PS II reaction center.
出处
《中国农业科学》
CAS
CSCD
北大核心
2005年第7期1373-1378,共6页
Scientia Agricultura Sinica
基金
国家"863"项目(2001AA246012)
国家自然科学基金项目(30170164)
