Virus inoculation and visualization of disease symptoms
All viruses were inoculated 14 days after plants were treated with different hydrogels. The rubbing method was used to inoculate TMV labeled with a green fluorescent protein (GFP) in hydrogel treated plants or CML30 silenced plants. The agroinfiltration was used to inoculate TRV-GFP, TuMV-GFP and PVX in hydrogel treated plants. The infection of virus-GFP in N. benthamiana was observed under UV lamp (Blak-Ray B-100AP, Upland, CA, U.S.A.) at the appropriate time (TMV-GFP: 2 and 7 dpi, TRV-GFP: 5 and 9 dpi, TuMV-GFP: 12 and 16 dpi). The infection of PVX in N. benthamiana was observed under a fluorescent lamp at 18 and 22 dpi. At the same time, the inoculated leaves and young leaves of each group were collected in liquid nitrogen and stored at -80 °C for a subsequent experiment.