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Plant bio

Plant pathogen IV

QuestionAnswer
Potato blight - Leading cause of potato crop loss
Phytophthora infestans Oomycete pathogen 5 day lifecycle Spores washed into soil by rain and blown long distances by wind Once on host zoospores released  Hyphae germinate spreading through plant & produce new spores
Causes of disease Same crop is grown repeatedly in the same area causing pathogen numbers to increase  Ensuring no infected tubers are left after harvest Using good-quality seed potatoes from suppliers  heat-treating soil or potting medium to 49 °C for 30 minutes
Cause of disease Crops experience stressful conditions, eg drought, flooding or heatwaves Weather forecasting  Smith Period - two consecutive days where min temperature is 10 °C or above and least 11 hours of each day has greater than 90% relative humidity
Fungicide use Preventative Foliar-applied fungicide sprays Organic farming - Copper pesticides Timing UK - spraying every few weeks African smallholders - every three days Drawbacks Fungicide & copper toxicity
Cause of disease Overuse of a small number of fungicides & pesticides creates selection pressure for resistance Combine & replace fungicides regularly Mix single-target fungicides with broad-spectrum fungicides New, more effective compounds regularly created
Cause of disease Breeding for fast growth and high yield (not disease resistance) Breeding for resistance Limited success - difficulty breeding potato to wild relatives Many varieties very susceptible but grown due to demand
Solanum americanum – Potential Source of Resistance Closely related – same genus Fruits easily Resistant to P. infestans Small genome Inbreeding
S. americanum has variation To find the gene responsible for resistance… DNA sequencing Resistance vs susceptability
Identified gene can be added into potato Traditional breeding: Requires closely related species Generally difficult in potatoes Genetic engineering: Any combination of genes and regulatory elements Transfer between unrelated species
Genetic Engineering can mean several things Genetic Modification: DNA is changed by modern biotechnology to create a new combination of genes and regulatory elements
Genetic Engineering can mean several things Genetic Editing: A section of DNA is targeted to insert or delete one or more base pairs
Genetic Engineering can mean several things Precision Bred Organism: Targeted genetic changes made to produce beneficial traits that can also occur through traditional breeding or natural processes
Genetic Modification DNA is changed by modern biotechnology to create a new combination of genes and regulatory elements Many genetic changes are not GMOs - specific hybrids - changing chromosome number - selective breeding - mutagenesis
Genetic Modification - agrobacterium used to create GMOs - selective markers - GM plants heavily regulated
Genetic editing A section of DNA is targeted to insert or delete one or more base pairs - CRISPR genes can then be bred away
Precision Bred Organism Targeted genetic changes: CRISPR editing Produce beneficial traits: Agricultural Commercial Nutritional
Precision Bred Organism Could have occurred naturally / via traditional breeding Species hybrids Mutagenesis Changing chromosome number DNA recombination & rearrangements
Stacking Overuse of a small number of fungicides & pesticides creates selection pressure for pathogen resistance Resistance genes should be used in stacks & updated regularly
Created by: reub8n
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