bio 7.2

plant fungal infections sign and symptoms

Signs:

• Leaf rust, Stem rust

• White mould

• Powdery mildew

Symptoms:

• Birdseye spot on berries

• Damp seeds

• Brown leaf spots

• Yellowing leaves

plant bacterial infections signs and sympotoms

Signs:

• Ooze

• Water-soaked lesions

• Bacteria stream in water from stem cut

Symptoms:

• Fruit spot

• Canker, crown gall

• Fruit spot

• Shepherd’s crook stem ends in woody plants

plants viral infection signs and symptoms

No signs - pathogens cannot be directly observed

passsive (innate) plant defences : physical

passsive (innate) plant defences : physical

passsive (innate) plant defences : chemical

• Defensins: block pathogen growth in seeds

• Resins and Tannins: antimicrobial agents

• Oils repel pests

• Gum seals area

Active (Induced) Plant Defences

• Thickened cell wall: cytoplasm accumulates around invasion site to isolate

• Hypersensitive reaction/ Programming cell death :

  • Rapid cell death initiated by plant OR

  • Endophyte assistance: roots release chemical to attract beneficial bacteria to fight infection

  • Loacalsied responde activnared so taht eh painft does tn respond 

  • Plants cells in that region 

Active (Induced) Plant Defences

• Abscission layer: hormones trigger formation of a layer around infection to separate infected tissue and cause it to drop off

Fungal Case Study - Phytophthora

• Fungus that infects banksias, eucalyptus and camellias

• Attacks the roots and stems of plants & destroys the root system which reduces the plants ability to absorb water and nutrients

• Above the ground symptoms include yellowing, wilting, dried foliage.

• World Heritage sites have been alerted, including; Barrington Tops NP, Wollemi NP, southern NSW Eden NP.

• This fungus increases rapidly when conditions are moist and warm within the root system

what is the first line of defence

Innate is non specific it provide the first and second line of defence form pathogens form birth 

nonspecific : response does not change to the pathogen 

types of first line of defence

physical and chemical

physical first line of defence

Physical : blocking you pathogens from getting in

Skin: Thick layer of dead cells, periodic shedding to remove microbes, acidic → slowing the growth of the bacteria and good bacteria compete with bad bacteria, sebum → fatty acid 

sweat: through a constant outward flow that pushes microbes away from pores and a unique chemical makeup that physically breaks down germs.

Hair: Filters air that contains dust, microbes, pollutants in nose

Cilia: hairs that line upper respiratory tract, traps and propels droplets, mucus → sweep pathogens to exist 

Mucus and earwax: trap pathogens

Urine: flushes microbes through urethra

excretion : 

• vomiting, urine →  expels microorganisms

• saliva tears → chemicals that kill pathogens → lysozyme, dilutes/ washes 

Microbiome: beneficial microorganisms on skin and intestines compete with pathogens

Chemicals 

Chemicals on skin surface or internal epithelium minimise pathogenic growth

• Acidity of skin: inhibits bacterial growth

• Gastric acid: acidity of stomach (pH 2-3) destroys bacteria/toxins

• Lysozymes: enzyme produced in tears, saliva, sweat. Breaks down cell walls

• Saliva: contains lysosomes, dilutes number of organisms and washes teeth/mouth

• Sebum: fatty acids provide protective film on skin to inhibit bacterial growth

• Hyaluronic acid: gelatinous substances that slows spread of toxins

chemical second line of defence

Chemicals 

Chemicals on skin surface or internal epithelium minimise pathogenic growth

• Acidity of skin: inhibits bacterial growth

• Gastric acid: acidity of stomach (pH 2-3) destroys bacteria/toxins

• Lysozymes: enzyme produced in tears, saliva, sweat. Breaks down cell walls

• Saliva: contains lysosomes, dilutes number of organisms and washes teeth/mouth

• Sebum: fatty acids provide protective film on skin to inhibit bacterial growth

• Hyaluronic acid: gelatinous substances that slows spread of toxins

what is the second line of defence

When pathogens break through the first line of defence, a non-specific innate response is triggered. 

• Phagocytosis

• Inflammation

• Antimicrobial proteins

what is phagocytosis

• Target smaller pathogens

• Act more quickly but live for 1-2 days

• Fight short-term acute infections

what are neutrophils ( non specific)

• Target smaller pathogens

• Act more quickly but live for 1-2 days

• Fight short-term acute infections

what is a macrophafge

• Target smaller pathogens

• Act more quickly but live for 1-2 days

• Fight short-term acute infections

what is inflammation

• Target smaller pathogens

• Act more quickly but live for 1-2 days

• Fight short-term acute infections

explain the whole 3 line of defence

what are the 2 types of immunity

• Active immunity:involves the production of antibodies by the body itself and the subsequent development of memory cells. 

• Passive Immunity: acquisition of antibodies from another source and memory cells are not developed.

Case study: HPV

Human papillomavirus is a STD which can lead to cervical cancers. 

• Vaccine incorporated into Australia’s National Immunisation Programme (NIP)

  • >50% of females under 30 are vaccinated

  • Evidence shows school-based immunisation has significantly lowered rates of cervical abnormalities

• Side effects are predominantly mild, safety records like other well-established vaccines.

Types of vaccines 

 Viral

1. Purified/Disabled Virus – Polio, Rabies, Hep A

2. Weakened virus - measles, mumps, chicken pox

3. Inject a protein from the virus – HPV, Hep B, Influenza

●Bacterial

1. Inject Polysaccharide (sugar) coating of bacteria - meningococcal

2. Inject proteins from the bacteria - Whooping cough

3. Inject a toxin (protein) from bacteria – Tetanus, Diphtheria

●New Methods

1. Inject mRNA – inoculate people with a gene to create proteins to produce antibodies - Covid-19

2. Replicate a Defective Virus (one that can not reproduce once inside the body) – created in vitro and inserted into humans