posted on 2023-06-06, 15:37authored byXiang Xu, Yubing Jiao, Lili Shen, Ying Li, Yunpeng Mei, Wengang Yang, Changquan Li, Yi Cao, Fenglei Chen, Bin Li, Jinguang Yang
Most crop viruses are carried and spread by seeds. Virus-infected
seeds are seed-borne viral disease infections, and thus, reducing
the rate of seed infection is an urgent problem in the seed-production
industry. The objective of this study was to use nanoparticles (NPs)
to directly deliver dsRNA into plants or pollen to initiate RNA interference
(RNAi) to reduce viral carryover in seeds. Chitosan quaternary ammonium
salt (HACC), complexed with dsRNAs, was selected for targeting the
genes for the tobacco mosaic virus (TMV) coat protein (CP) and TMV
RNA-dependent RNA polymerase (RdRP) to form HACC-dsRNA NPs. These
NP-based dsRNAs were delivered to the plants using four different
methods, including infiltration, spraying, root soaking, and pollen
internalization. All four methods were able to reduce the seed-carrying
rate of offspring seeds of the TMV-infected plants, with pollen internalization
being the most effective in reducing the TMV-carrying rate from 95.1
to 61.1% in the control group. By measuring the plant uptake of fluorescence-labeled
NPs and dsRNAs, the transportation of the HACC-dsRNA NPs into the
plants was observed, and the uptake of dsRNA in combination with small
RNA sequencing was further confirmed, resulting in the silencing of
homologous RNA molecules during the topical application. The results
demonstrated that the incidence of TMV infection was reduced by various
degrees via RNAi induction without the need to develop transgenic
plants. These results demonstrate the advantages of NP-based RNAi
technology in breeding for disease resistance and developing a new
strategy for virus-resistant breeding in plants.