P-370 - Understanding Rose Rosette Disease: Viral Dynamics and Host Response Leading to Rosetting

Rose rosette disease (RRD) is caused by Rose rosette virus (RRV), marked by stem thickening, hyper-thorniness, malformed and discolored leaves and flowers and clustering of branches tightly around the apical growing point of a stem. The aim of this project is to understand the molecular mechanisms underpinning the rosetting phenotype. RRV accumulation was determined by RT-qPCR to be significantly higher in symptomatic than asymptomatic tissues. Three plant hormones affecting plant growth and development, ABA, IAA, and GA accumulated to distinct levels in symptomatic and asymptomatic tissues. RNAseq analysis was performed using pooled samples from rosetting, non-symptomatic, and healthy shoots. Quantitative differences were identified in the expression of key auxin factors influencing auxin biosynthesis, transport, and gene regulation that are known contributors to shoot architecture and flower development. Genes involved in zeatin, ABA, and GA biosynthesis and signaling were dysregulated in a manner pointing to their putative roles in rosetting disease. We demonstrate that genes that are known to control apical and lateral meristem development, prickle development, as well as flower development were uniquely altered in RRD expressing tissues.