16D10 siRNAs Inhibit Root-Knot Nematode Infection in Transgenic Grape Hairy Roots

To develop a biotech-based solution for controlling Root-knot nematodes (RKNs) in grapes, we evaluated the efficacy of plant-derived RNA interference (RNAi) silencing of a conserved RKN effector gene, 16D10, for nematode resistance in transgenic grape hairy roots. Two hairpin-based silencing constructs, containing a stem sequence of 42 bp (pART27-42) or 271 bp (pART27-271) of the 16D10 gene, were transformed into grape hairy roots and compared for their small interfering RNA (siRNA) production and efficacy on suppression of nematode infection.  Transgenic hairy root lines carrying either of the two RNAi constructs showed less susceptibility to nematode infection compared with control. Small RNA libraries from four pART27-42 and two pART27-271 hairy root lines were sequenced using an Illumina sequencing technology and several interesting molecular characteristics of 16D10-specific siRNAs from these libraries were observed.  This study demonstrated the feasibility of using a plant-derived RNAi approach for generation of novel nematode resistance in grapes and provided insights into optimizing plant RNAi constructs for enhancing silencing efficacies.