CHARACTERIZATION OF GENES CONTRIBUTING TO POTATO CYST NEMATODE RESISTANCE IN THE NONHOST SPECIES, SOLANUM SISYMBRIIFOLIUM.

Solanum sisymbriifolium(SSI), commonly called litchi tomato or sticky nightshadeIs resistant to a parasitic nematode of potatoes called Globodera pallida.This plantt secretes chemicals that "trick" otherwise dormant nematode eggs into hatching in the absence of a suitable host.The J2 larvae then chemotax towards the trap crop roots, invade, but are then killed or otherwise prevented from undergoing further molts to sexual maturity. The purpose of this study isto identify genes in SSI that protect it fromnematodes, anddetermine if these genes are capable of providing novel forms of nematode resistance in transgenic crops such as potato. We have identified 277 genes that change expression when SSI roots are infected by G. pallida. We have selected several of these genes for further study. Goal 1 will be to isolate and sequence the selected genes, and introduce them under the control of a strong promoter, into potatoes. The resulting plants will be then evaluated for increased nematode resistance. Objective 1:Isolate and sequence 4 kinase- and receptor kinase-genes from SSI, 2 NDR1/HIN1-like genes from SSI, and at least 4 representative peroxidase genes from SSI.Objective 2:Clone genes into plant expression vectors and transform them into potatoes.Objective 3:Assess the resistance of the transformed potatoes againstG. pallida, and additional pathogens such asPseudomonas syringaepv. DC3000,Phytophthora infestans, andMeloidogyne incognita, as facilities allow. Goal 2will be to develop effective protocols for stably transforming SSI so that we can knock out the selected genes and assess whether their loss renders SSI sensitive. Objective 4 will be to develop a protocol for SSI transformation using abeta-glucuronidase carrying T-DNA vector. If successful, we will then use CRISPR-Cas9 or RNAi to reduce expression of the genes under study in Objective 1. In this way, we will demonstrate whether these genes are essential for nematode resistance.