An efficient papaya leaf distortion mosaic potyvirus vector for virus-induced gene silencing in papaya

Papaya(Carica papaya L.)is regarded as an excellent model for genomic studies of tropical trees because of its short generation time and its small genome that has been sequenced.However,functional genomic studies in papaya depend on laborious genetic transformations because no rapid tools exist for this species.Here,we developed a highly efficient virus-induced gene silencing(VIGS)vector for use in papaya by modifying an artificially attenuated infectious clone of papaya leaf distortion mosaic virus(PLDMV;genus:Potyvirus),PLDMV-E,into a stable Nimble Cloning(NC)-based PLDMV vector,pPLDMV-NC,in Escherichia coli.The target fragments for gene silencing can easily be cloned into pPLDMV-NC without multiple digestion and ligation steps.Using this PLDMV VIGS system,we silenced and characterized five endogenous genes in papaya,including two common VIGS marker genes,namely,phytoene desaturase,Mg-chelatase H subunit,putative GIBBERELLIN(GA)-INSENSITIVE DWARF1A and 1B encoding GA receptors;and the cytochrome P450 gene CYP83B1,which encodes a key enzyme involved in benzylglucosinolate biosynthesis.The results demonstrate that our newly developed PLDMV VIGS vector is a rapid and convenient tool for functional genomic studies in papaya.

SUMOylation-modified Pelota-Hbs1 RNA surveillance complex restricts the infection of potyvirids in plants

RNA quality control nonsense-mediated decay is involved in viral restriction in both plants and animals.However,it is not known whether two other RNA quality control pathways,nonstop decay and no-go decay,are capable of restricting viruses in plants.Here,we show that the evolutionarily conserved Pelota–Hbs1 complex negatively regulates infection of plant viruses in the family Potyviridae(termed potyvirids),the largest group of plant RNA viruses that accounts for more than half of the viral crop damage worldwide.Pelota enables the recognition of the functional G1-2A6-7 motif in the P3 cistron,which is conserved in almost all potyvirids.This allows Pelota to target the virus and act as a viral restriction factor.Furthermore,Pelota interacts with the SUMO E2-conjugating enzyme SCE1 and is SUMOylated in planta.Blocking Pelota SUMOylation disrupts the ability to recruit Hbs1 and inhibits viral RNA degradation.These findings reveal the functional importance of Pelota SUMOylation during the infection of potyvirids in plants.