Mechant E, De Marez T, Aper J, Bulcke R
Ghent University, Faculty of Bioscience Engineering, Dept. Plant Production, Weed Science Unit, Coupure Links 653, BE-9000 Gent, Belgium.
Commun Agric Appl Biol Sci. 2010;75(2):83-90.
Sugar beet growers in Europe are more often confronted with an unsatisfactory control of Chenopodium album L. (fat-hen), possibly due to the presence of a triazinone resistant biotype. So far, two mutations on the psbA-gene, i.e. Ser264-Gly and Ala251-Val, are known to cause resistance in C. album to the photosystem II-inhibiting triazinones metamitron, a key herbicide in sugar beet, and metribuzin. The Ser264-Gly biotype, cross-resistant to many other photosystem II-inhibitors like the triazines atrazine and terbuthylazine, is most common. The second resistant C. album biotype, recorded in Sweden, is highly resistant to triazinones but only slightly cross-resistant to terbuthylazine. Since farmers should adapt their weed control strategy when a resistant biotype is present, a quick and cheap detection method is needed. Therefore, through trial and error, a protocol for detection with chlorophyll fluorescence measurements was developed and put to the test. First, C. album leaves were incubated in herbicide solution (i.e. 0 microM, 25 microM metribuzin, 200 microM metamitron or 25 microM terbuthylazine) during three hours under natural light. After 30 minutes of dark adaptation, photosynthesis yield was measured with Pocket PEA (Hansatech Instruments). In Leaves from sensitive C. album, herbicide treatment reduces photosynthesis yield due to inhibition of photosynthesis at photosystem II. This results in a difference of photosynthesis yield between the untreated control and herbicide treatment. Based on the relative photosynthesis yield (as a percentage of untreated), a classification rule was formulated: C. album is classified as sensitive when its relative photosynthesis yield is less than 90%, otherwise it is resistant. While metribuzin, and to a lesser extent, metamitron treatment allowed a quick detection of triazinone resistant C. album, terbuthylazine treatment was able to distinguish the Ser264-Gly from the Ala251-Val biotype. As a final test, 265 plants were classified with the protocol. Simultaneously, a CLeaved Amplified Polymorphic Sequence (CAPS)-analysis was conducted on the same plants to verify the presence of the Ser264-Gly mutation. Only one mismatch was found when results of both detection methods were compared. The test results illustrate that this protocol provides a reliable, quick and cheap alternative for DNA-analysis and bio-assays to detect the triazinone resistant C. album biotypes.
欧洲的甜菜种植者常常面临对藜（肥母鸡草）控制效果不理想的情况，这可能是由于存在对三嗪酮具有抗性的生物型。到目前为止，已知psbA基因上的两个突变，即Ser264 - Gly和Ala251 - Val，会导致藜对抑制光系统II的三嗪酮类除草剂苯嗪草酮（甜菜中的一种关键除草剂）和嗪草酮产生抗性。Ser264 - Gly生物型对许多其他光系统II抑制剂如三嗪类除草剂莠去津和特丁津具有交叉抗性，是最常见的。在瑞典记录的第二种抗性藜生物型对三嗪酮具有高度抗性，但对特丁津只有轻微的交叉抗性。由于当存在抗性生物型时农民应调整他们的杂草控制策略，因此需要一种快速且廉价的检测方法。因此，通过反复试验，开发了一种用于叶绿素荧光测量检测的方案并进行了测试。首先，将藜叶片在自然光下于除草剂溶液（即0微摩尔、25微摩尔嗪草酮、200微摩尔苯嗪草酮或25微摩尔特丁津）中孵育三小时。在暗适应30分钟后，使用便携式PEA（Hansatech Instruments）测量光合作用产量。在敏感藜的叶片中，除草剂处理由于抑制光系统II的光合作用而降低光合作用产量。这导致未处理对照和除草剂处理之间的光合作用产量存在差异。基于相对光合作用产量（作为未处理的百分比），制定了一个分类规则：当藜的相对光合作用产量小于90%时，将其分类为敏感型，否则为抗性型。虽然嗪草酮处理以及在较小程度上苯嗪草酮处理能够快速检测出对三嗪酮具有抗性的藜，但特丁津处理能够区分Ser264 - Gly生物型和Ala251 - Val生物型。作为最终测试，使用该方案对265株植物进行了分类。同时，对同一批植物进行了切割扩增多态性序列（CAPS）分析，以验证Ser264 - Gly突变的存在。当比较两种检测方法的结果时，仅发现一处不匹配。测试结果表明，该方案为检测对三嗪酮具有抗性的藜生物型提供了一种可靠、快速且廉价的替代DNA分析和生物测定的方法。
