Virome characterization of native wild-rice plants discovers a novel
pathogenic rice Polerovirus with world-wide circulation
Abstract
Pandemics originating from zoonotic viruses have posed significant
threats to human health and agriculture. Recent discoveries have
revealed that wild-rice plants also harbor viral pathogens capable of
severely impacting rice production, a cornerstone food crop. In this
study, we conducted virome analysis on ~1000 wild-rice
individual colonies and discovered a novel single-strand positive-sense
RNA virus prevalent in these plants. Through comprehensive genomic
characterization and comparative sequence analysis, this virus was
classified as a new species in the genus Polerovirus, designated Rice
less tiller virus (RLTV). Our investigations elucidated that RLTV could
be transmitted from wild-rice to cultivated rice via a specific insect
vector, the aphid Rhopalosiphum padi, causing less tiller disease
symptoms in rice plants. We generated an infectious cDNA clone for RLTV
and demonstrated systemic infection of rice cultivars and induction of
severe disease symptoms following mechanical inoculation or stable
genetic transformation. We further illustrated transmission of RLTV from
stable transgenic lines to healthy rice plants by the aphid vector,
leading to the development of disease symptoms. Notably, our database
searches showed that RLTV and another polerovirus isolated from a wild
plant species are widely circulating not only in wild rice but also
cultivated rice around the world. Our findings provide strong evidence
for a wild plant origin for rice viruses and underscore the imminent
threat posed by aphid-transmitted rice Polerovirus to rice cultivar.