Lecture 5 - Soilborne Diseases

Amplicon

RNA /DNA piece that is the source / product of amplification events (e.g. during PCR) used to study specific genes or sequences in various applications.

Biofumigation

Incorporating a Brassica cover crop into the soil to release volatiles for disease control

Chlorosis

loss of chlorophyll molecules from the leaf = yellowing of the leaf

Glucosinolates

organic compounds in Brassicas containing Sulphur & Nitrogen that are responsible for the release of bioactive substances during decomposition.

Grafting

surgical process to ensure plant has genetically distinct shoot & root system

Myrosinase

enzyme in Brassica vacuoles, when release converts glucosinolates to toxic volatiles which can deter herbivores and pathogens.

Notifiable

the grower has a legal obligation to report the presence of this soilborne disease to relevant authorities for monitoring and control.

Obligate

Pathogen requires presence of a host to complete its life cycle and cannot survive without it.

PCR

polymerase chain reaction = molecular biology technique to rapidly synthesise DNA

qPCR

quantitative technique to monitor levels of a specific DNA molecule during PCR amplification.

Senescence

natural (or disease-induced) completion of crop life cycle – often involves grain filling and maturation, leading to decreased photosynthetic activity.

Solarisation

covering soil with plastic to warm it, thereby effecting disease control and improving soil health.

Trap Crop

pathogen can infect roots but cannot complete its life cycle in this host , thus acting as a decoy to protect the main crop.

Zoospore

motile infection stage of certain soilborne diseases (e.g. Plasmodiophora) that can swim in water, facilitating the spread of pathogens and infections in soil.