Strawberry vein banding virus (SVBV)-infected strawberry cells contain cytoplasmic inclusions with isometric particles.  To identify the components of the inclusions, green fluorescent protein (GFP) was fused to the carboxy-terminus (C-terminus) of SVBV open reading frames, these constructs were separately transformed into Agrobacterium tumefaciens and infiltrated into Nicotiana benthamiana leaves.  Results showed that the SVBV P6 protein assembled into prominent and amorphous inclusion bodies (IBs).  To investigate P6 subcellular localization, P6-GFP was ectopically expressed in N. benthamiana leaves by agroinfiltration and then stained with 4´,6-diamidino-2-phenylindole (DAPI).  We found the P6 protein accumulated in the nuclei and also formed cytoplasmic IBs with different sizes.  To further determine the location of P6 IBs in the cytoplasm, and explore whether the P6 IBs move freely or depend on cytoskeleton and endoplasmic reticulum (ER), the microfilament marker protein (GFP-ABD2-GFP), microtubules marker protein (mCherry-MAP65-1) and ER marker protein (mCherry-HDEL) were separately coexpressed with P6-GFP and into N. benthamiana leaves by agroinfiltration, exhibiting that P6 IBs aligned with cytoskeleton and endoplasmic reticulum.  Meanwhile, coinfiltration of P1 and P6 indicated the P6 colocalized with the P1 protein at periphery of cells.  The P6 protein contains one C-terminal nuclear localization signal (NLS) region, a P6 protein mutant with a deleted NLS did not localize in the nucleus, did not form IBs, and was unable to facilitate exogenous GFP expression.  These results demonstrate that the deleted NLS region is an important P6 domain required for biological functions.  In summary, the mobile P6 IBs are associated with ER, microfilaments and microtubules and move along microfilaments to the SVBV P1 protein in the PD. 

 

Resistance of five field populations of Mythimna separata (Walker) collected from Shaanxi and Shanxi provinces of China to six different insecticides was evaluated by leaf dip method in the laboratory.  The results showed that all populations were relatively sensitive to emamectin benzoate with a resistance ratio (RR) of 0.583–1.583 folds.  All populations showed susceptible or low level resistance to chlorantraniliprole and beta-cypermethrin.  Compared with a relatively susceptible strain of M. separata, the resistance level of the whole populations ranged from susceptible to moderate to chlorpyrifos and lambda-cyhalothrin, moderate to high to phoxim (RR=19.367–70.100) except for population from Sanyuan County (RR=2.567).  Pair-wise correlation analysis among different insecticides indicated that chlorpyrifos has a significantly positive and significant correlation with emamectin benzoate.  Chlorantraniliprole didn’t have significant correlation with emamectin benzoate, chlorpyrifos and phoxim.  Therefore, emamectin benzoate, chlorantraniliprole and beta-cypermethrin are recommended to control oriental armyworm.  Meanwhile, to postpone the occurrence and development of insecticide resistance in Shaanxi and Shanxi provinces, alternative and rotational application of insecticides between chlorantraniliprole and emamectin benzoate or chlorpyrifos is necessary.