Collin Hudzik Abstract:

Cuscuta campestris is an obligate parasitic plant which attaches to host stems through a specialized organ called the haustoria.  While bidirectional movement of photosynthates, proteins, microRNAs, etc between the parasite and host facilitated by the haustoria is characterized, it is unknown whether virulence factors from the haustoria impact overall host performance.  Previous research has identified multiple microRNAs accumulating in the haustoria during parasitism of A. thaliana which target and silence mRNAs involved in development, defense, and other biological processes through the production of secondary short interfering RNAs (siRNAs).  Because tomato (Solanum lycopersicum)is an world-wide important crop and often a host to C. campestris, the same miRNAs identified during infection of A. thaliana was also confirmed at the haustoria interface of tomato.  All previous experiments which identified trans-species miRNAs were performed ten days after infection of the parasite. In order to understand when trans-species miRNAs are active during infection, a time course experiment was performed starting from initial contact with a host and lasted a total of 14 days.  sRNA sequencing was performed at the host parasite interface and showed that trans-species miRNAs begin expression two days after initial contact with a host. It is also unknown which cells are responsible for trans-species miRNA production. Laser ablation tomography was performed at the same time interval as the sRNA sequencing experiments to identify the stage of haustorium development where trans-species miRNAs are able to be produced.