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LEC 144 - Global Change Biology - Coggle Diagram

- - - - potato blight thought to become more problematic under CC
      - to deal with potato blight:
        
        resistance genes already existing in wild relative species
        
        potato (Solanum) spp have co-evolved with Phytophthora infestans for generations
        
        difficult to breed blight resistant potatoes as it takes time: one generate a year
  - - - method:
        
        Stress tolerant crossed with existing elite
        
        select the offspring that show both traits
        
        cross the two parental lines to produce offspring (F1 Hybrid)
        
        multiple generations of backcrossing to recover most of genetic material of original elite line over time
        
        select wild relatives showing trait of interest
      - advantages
        
        limited tech required
        
        socially acceptable
        
        works and is free
      - disadvantages
        
        difficult to modify multi-genic traits
        
        high genetic uniformity --> vulnerability
        
        time consuming + labour intensive
      - can plant breeding keep up with CC?
        
        green revolution from semi-dwarf cereal varieties + improved agronomy led to gains in cereal yield and pop growth but by 2000, parity in cereal population + pop growth
  - - - experimental trials e.g. implementing cc treatment
      - historical yield/environmental analysis
      - predictive yield modelling for the future - crop simulation models
    - - to cope: experimentally impose high temperatures
        
        screen varieties in the field by late planting
        
        augment natural temp variation e.g. put a screen over the crop
- - - - • Maize promoter & sunflower transcription factor HaHB4 - smaller grains but more of them = more yield
  - - - introducing genes may induce allergenic responses
        
        herbicide residues e.g. glyphosate
    - - positive selection pressure results in herbicide resistant weeds (though not a uniquely GM problem)
        
        toxic GM pollen falling on milkweed eaten by monarch caterpillars (though 89% of Bt pollen falls within 5 metres of the field)
    - - happens through: wild relatives being in pollen dispersal radius; gene flow detected up to 50m in experiments with superweed - most likely dispersal method is seed loss during transit to factory
  - - - • AtGolS2 GM work was proof-of-concept - another 5-10 years to produce non-GM rice using same concept; meanwhile other genes investigated (2020 paper)
      - • Chinese rice self-sufficiency via conventional breeding / agronomy - no GM need ?
      - • Public attitudes driving GM policy ? (Scientists attacked @ public lectures)
- - - - nitrogen monoxide
      - sulphur dioxide
    - - nitrogen dioxide
      - ozone
- - - - By increasing the gradient for CO2 uptake
      - BUT
      - Since C4 plants achieve high [CO2] in the bundle sheath even under ambient atmospheric conditions there is little/no increase in the efficiency of RUBISCO (i.e. no decrease in photorespiration)
      - temperature-related increases in photosynthesis are far greater in C4 plants than in C3 plants
        
        that being said, direct effect of increased CO2 on photosynthesis is greater in C3 than C4 plants
- - - - reduce light interception by reducing leaf area
      - reducing efficiency with which light is utilised (~ photosynthesis)
      - most often a combo of both
- - - - fibre conc
      - cellulose content
      - tannin conc
      - toughness
      - severity of herbivory decreases with increased:
    - - water content
      - nitrogen content
  - - - tannin conc
      - lignin cont
      - C:N ratio
      - lignin:N ratio
    - - nitrogen conc
- - - - examples of triggers: Heat stress, light stress, cold stress, high dissolved inorganic nitrogen, hypoxia, hyposalinity, acidification
      - examples of endpoints:
        
        Cell death of host
        
        Digestion of symbiont by host
        
        Expulsion of symbiont (exocytosis or vomocytosis)
        
        Host cell detachment
      - examples of cascades:
        
        unfolded protein responses
        
        photoinhibition of symbiont
        
        disruptive balance of nitrogen and phosphate btw coral and symbiont
- - - - Ocean currents – coral larvae are positively buoyant, passive particles so the direction and speed of dispersal depends on surface ocean currents