Phytophthora root rot (PRR) is the most severe and damaging disease in avocado plantations in South Africa. The causal agent, Phytophthora cinnamomi, is an oomycete that also causes disease on thousands of other plant species. The pathogen is a heterothallic species that can reproduce by sexual or asexual means. It can persist in soil or infected plant material for extended periods of time, and there is no means to eradicate this oomycete from infected areas once the pathogen has successfully established in soils. Currently, phosphite injections, along with the use of good agricultural practices, are commonly used as methods of control for PRR.

Given the severity of the disease, however, little is known regarding the biology, population diversity, and the molecular basis for the P. cinnamomi - avocado interaction. Current research of ARP therefore focuses on characterizing the genetic diversity and monitoring pathogen populations using microsatellite markers, and using genomics and genetics tools to characterize effectors genes (RxLR and Crinkler) as well as other genes that are known to contribute to the pathogenicity of the oomycete. The sensitivity and effectiveness of phosphite control and its mode of action towards P. cinnamomi is also being investigated.

 

ARP Team Members

·         Melissa Joubert: Identification and expression analysis of RxLR effector genes in Phytophthora cinnamomi

·         Mohamed Seedat: Identification of CRN effector genes in Phytophthora cinnamomi during avocado root infection

·         Tsakani Miyambo: The identification and characterization of polygalacturonases in Phytophthora cinnamomi

·         Juanita Hanneman: Analysing the effect of phosphite on the morphology and transcriptome of South African Phytophthora cinnamomi strains

·         Juanita Engelbrecht: Population genetics and genomics of Phytophthora cinnamomi