| Deep application of agrochemical in rice fields and seedlings coating pesticide are efficient ways to achieve simple rice cultivation.Insecticides applied by these methods must be absorbed by rice seeds or roots and then distributed to various parts of the plant to exert their effects.Transporter proteins play an important role in the uptake and translocation of pesticides in crops.Constructing a simple and fast transient expression system provides a basis for studying the transport mechanism of pesticides in crops.In this study,we evaluated the interaction differences among 51 rice varieties and 4 neonicotinoid pesticides,and constructed a transient expression system for functional analysis of pesticide transporters in planta.The main results as follows:(1)A total of 51 rice cultivars were selected,and the pesticide contents in the roots and leaves of rice were detected by ultra-performance liquid phase(UPLC)and gas chromatography(GC)after being treated with neonicotinoids insecticides.At the same time,Win RHIZO software was used to measure the morphological indexes of the roots,and to evaluate the effect of neonicotinoid insecticides on root growth during seed germination.Obtaining rice varieties with high absorption pesticides will help to understand the mechanism of pesticide transport in crops.The results show that different rice varieties showed largely variation in their ability of uptake neonicotinoid pesticides,and their root to shoot neonicotinoid pesticides translocation rate were also significant different.The effect of neonicotinoid pesticides on the root morphology in rice varieties were also largely variation.Seven cultivars,Jinyuyou 397,Guiyu 9,Guang 8 You 169,Xunliangyou 78,Nongle 1 and Wuyou 1179 with the high ability of uptake and utilization of neonicotinoid pesticides were selected from the 51 cultivars tested.(2)The response of the two cultivars Wuyou 1179 and Longliangyou 1988 to either broadcasting fertilizer and spraying thiamethoxam(MFP)or buried fertilizer and thiamethoxam(DFP)was compared.The DFP treatment provided a superior level of control against the rice planthopper and rice case worm,and also boosted plant height,tillering and grain yield.Measurements of the thiamethoxam residue in the root,shoot,grain,husk and the soil showed that they were met the requirement of the safe standard.This study enhances our understanding of the uptake and distribution of thiamethoxam used in whole mechanization tillage mode and provided an idea to select and breeding pesticide-easyapplication crop for mechanization tillage mode,so that to reduce the pesticide application.(3)Agrobacterium-mediated transient expression system of nicotiana benthamiana was used to study the function of plant transporters and pesticides.The results show that Nt NUP1 transporter can increase the absorption of nicotine in both tobacco leaf discs and protoplasts,which proves that the tobacco transient expression transporter system is feasible for studying pesticide transporters in planta.In order to confirm whether the tobacco transient expression system is suitable to study the function of the pesticide transporters,we used it to carried out the functional analysis of 9E2,a metocard candidate transporter.The results showed that transient expression of 9E2 transporter in tobacco leaf discs led to the increased the uptake of metocarb.The absorption experiments of Xenopus oocytes and rice 9E2 mutants also proved that 9E2 could mediate the translocation of medocarb.The results indicate that tobacco transient expression system is a fast,easy and reliable tool for identification of transporter function in planta. |
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