Engineering Research Centre of Plant Growth Regulators, Ministry of Education, College of Science, China Agricultural University, Beijing, PR China.
Heze Agricultural Bureau, Heze, PR China.
Pestic Biochem Physiol. 2017 Nov;143:265-271. doi: 10.1016/j.pestbp.2016.12.003. Epub 2016 Dec 7.
Glutathione S-transferases (GSTs) have been widely studied in relation to their role in herbicide tolerance and detoxification. However, a detailed characterization of GSTs from herbicide tolerant and sensitive maize cultivars is still lacking. In this study, we determined the mechanism of differential tolerance between two maize cultivars which had 4-fold difference tolerance to metolachlor. The metabolism rate of metolachlor was more rapid in the tolerant cultivar (Zea mays L. cv Nongda86) than the susceptible one (Zea mays L. cv Zhengda958). Addition of the GST inhibitor ethacrynic acid reduced the metabolism of metolachlor indicating the involvement of GSTs in the differential detoxification of metolachlor. The expression profiles of 32 GST isozymes were measured using quantitative RT-PCR. The results showed the expression of GST genes were slightly up-regulated in Nongda86, but severely inhibited in Zhengdan958 24h after metolachlor treatment. The genes GSTI, GSTIII, GSTIV, GST5, GST6 and GST7, which can detoxify chloroacetanilide herbicides, were all expressed higher in Nongda86 compared to Zhendgan958. The result of GST activity was consistent with the gene expression profiles. Collectively, higher-level expression of GST genes, leading to higher GST activity and faster herbicide detoxification, appears to be responsible for the difference in tolerance to metolachlor in two maize cultivars.
谷胱甘肽 S-转移酶（GSTs）在除草剂耐受性和解毒方面的作用已得到广泛研究。然而，对于具有除草剂耐受性和敏感性的玉米品种中 GSTs 的详细特征描述仍然缺乏。在这项研究中，我们确定了两个玉米品种之间差异耐受性的机制，这两个品种对甲草胺的耐受性差异高达 4 倍。在耐受品种（玉米 L. cv 农达 86）中甲草胺的代谢率比敏感品种（玉米 L. cv 郑达 958）更快。添加 GST 抑制剂 ethacrynic acid 可降低甲草胺的代谢，表明 GSTs 参与了甲草胺的差异解毒。使用定量 RT-PCR 测量了 32 种 GST 同工酶的表达谱。结果表明，在甲草胺处理 24 小时后，Nongda86 中的 GST 基因表达略有上调，但在 Zhengdan958 中则严重受到抑制。可以解毒氯代乙酰胺类除草剂的 GSTI、GSTIII、GSTIV、GST5、GST6 和 GST7 基因在 Nongda86 中的表达均高于 Zhendgan958。GST 活性的结果与基因表达谱一致。总的来说，GST 基因的高水平表达，导致 GST 活性更高，除草剂解毒更快，这似乎是两个玉米品种对甲草胺耐受性差异的原因。
