Study On The Mechanism Of Selective Action Of Fenclorim Between Oryza Sativa And Echinochloa Crusgalli

Pretilachlor is one of the most widely used herbicides in rice fields in Southeast Asian countries,it is often used in combination with herbicide safener because it is easy to cause herbicide injury.Fenclorim is one of the commonly used amide herbicide safener,which can protect crops from herbicide injury without affecting the herbicide’s weed control efficiency.The mechanism of selective action of the safener has not been clarified,and there is no clear conclusion on whether it has an effect on weed resistance.In order to further clarify the action mechanism of fenclorim,in this paper,we used the indoor agar culture method to clear the difference in the inhibition of pretilachlor on the growth of rice and Echinochloa crusgalli by fenclorim.Then the effects of pretilachlor and fenclorim on membrane lipid peroxidation,chlorophyll content,antioxidant enzyme and GSTS activity of rice and Echinochloa crusgalli were compared.In addition,the reasons for the difference of fenclorim detoxification in rice and Echinochloa crusgalli were explored at the molecular level.The purpose is to elucidate the mechanism of selective protection of fenclorim.The main results are as follows:1.Physiological and biochemical mechanism of detoxification of pretilachlor by fenclorimPretilachlor caused serious oxidative damage to rice and Echinochloa crusgalli.Fenclorim had no effect on the contents of chlorophyll,TBARS and antioxidant enzyme activities of rice,but could reduce membrane lipid peroxidation and oxidative stress of rice caused by pretilachlor.However,the content of chlorophyll and TBARS in Echinochloa crusgalli was increased by fenclorim,although the activity of antioxidant enzymes was not affected.The results showed that the antioxidant enzymes of rice and Echinochloa crusgalli could not be induced by fenclorim,but it could reduce the oxidative damage caused by pretilachlor in rice,and increase the oxidative damage caused by pretilachlor to Echinochloa crusgalli.Inhibitor tests had shown that ABC transporters and GSTs inhibitor could significantly increase the sensitivity of rice to pretilachlor,but only GSTS inhibitor increased the sensitivity of Echinochloa crusgalli to pretilachlor.These results indicated that GSTs and ABC transporters were closely related to the metabolism of pretilachlor in rice,while the metabolism of pretilachlor in Echinochloa crusgalli was only related to GSTs.GSTs assay showed that fenclorim only induced the activity of GSTs in rice but did not induce GSTs in Echinochloa crusgalli.2.Molecular mechanism of detoxification of pretilachlor by fenclorimThe analysis of transcriptome showed that the metabolizable detoxification genes induced by fenclorim in rice were more than those induced in Echinochloa crusgalli,in which 90.2% of metabolizable detoxification response genes in rice were upregulated,while only 22.0% of metabolizable detoxification response genes in Echinochloa crusgalli were up-regulated.Fenclorim can induced the up-regulation of the GST gene in rice,but not the up-regulation of the GST gene in Echinochloa crusgalli.Validated by q RT-PCR,it was determined that rice GSTF14,GSTU18,GSTU19,GSTU37 genes are related to the mechanism of action of fenclorim.3.Proximal gene analysis of GSTs gene family in Oryza sativa and Echinochloa crusgalliThe GSTs genes of Oryza sativa(japonica Oryza sativa)and Echinochloa crusgalli were classified according to the definite genes of Oryza sativa(indica Oryza sativa),blue mustard and potato.There were 11 subfamilies of Oryza sativa and 10 subfamilies of Echinochloa crusgalli.The differential response of 3 pairs of proximal genes in rice and Echinochloa crusgalli to fenclorim were determined by q RT-PCR,the result showed that the Oryza sativa GSTs gene expression upregulated,Echinochloa crusgalli GSTs gene downregulated or not induced.Through the research in this part,the molecular mechanism of fenclorim was preliminarily revealed.It indicates that the selectivity of fenclorim may be caused by the combined action of antioxidant system and metabolic detoxification system,and the difference in the induction of GSTs may be an important reason for fenclorim selectivity.