Mr Quentin Santana

PhD Student
Tree Protection Co-operative Programme

Research Interests

Pitch canker of Pines

Pitch canker is a devastating disease of pines that is affecting pine plantations and forests around the world. This disease is caused by the ascoymycete fungus Fusarium circinatum, a member of the Gibberella fujikuroi species complex. The disease is characterised by the mass exudation of pitch from infection sites, these sites are often cankers that are resin soaked. Other important distinguishing symptoms include branch tip die back as well as needle necrosis. In South Africa, Fusarium circinatum has mainly been a problem in the pine seedling nurseries, where young pine seedlings infected with the fungus suffer from root and root collar disease. Recently, outbreaks of the pitch canker disease has been observed in mature pine plantations within the Eastern and Western Cape regions of South Africa.

 

Most filamentous fungi such as Fusarium circinatum undergo a process called vegetative compatibility whereby two hyphal cells fuse to form a heterokaryotic cell. These heterokaryotic cells have two distinct nuclei in the heterokaryotic cell whereas the cytoplasm is a mixture of the two original cells. The entire process is governed by vegetative compatible (vic) or heterokaryon compatible genes (het). These genes act as a recognition system in fungi and determine if the two cells will be able to remain as a heterokaryotic cell. If these genes are found to incompatibile the fused cells undergo programmed cell death and the heterokaryon is lost.

My PhD entails the determining the location of these genes in the Fusarium circinatum genome using markers such as microsatellites and amplified fragment length polymorphisms (AFLP) in a genetic linkage map. By locating these genes it will allow us to better understand the biology of this plant pathogen and in the future possible control measures.