Ethylene

Pheromones

Chemical messengers that are broken down by individuals and released in the environment to the elect a response from a different individual.

Parasitoids

* free living adults that are like larvea
* they must kill their hosts and to complete a development

Systemin

a hormone that is released in damaged cells

Hypersensitive Response

* a mount a defense

Stages of a Hypersensitive Response

1. somata closes to keep out the pathogens
2. Toxins target the pathogen which are produced
3. Cell Walls are reinforced to a pathogen movement
4. Rapid Sucicide by the cells in the infected area

**SAR** Systemic Aquired Resistance

* primes roots or shoots to resist the assult
* a hormone that is produces at the infection site that triggers a slower more widespread set of events
* the signal results in the expression of a suite of that pathogen related genes **(** **PR)**

Methyl Sallicitate **MeSA**

* hormone that is responsible for **SAR**
* levels increase dramatically after the tissues are infected with the pathogen
* adding this to tobacco plants can help to the increase of SAR but decrease in plant development

Plant psychical defenses

* wax cuticle covering epidermal cells ( the skin) is an effective barrier to many pathogens
* Thorns, spines and trichomes protect leaves and stems from damage in herbivores

Ethylene Gas

* present in inches smoke
* induces production of enzymes that help in fruit ripening
* increases cellular respiration in ATP
* controls fruit ripening
* \

Auxin

* produced in healthy leaves and transported from leaf to stem through the petiole
* the leaves age and respond to the changes in the temperature and day length which is when this is less produced

**increase ethylene sensitivity**

* activates enzymes that weaken the walls of the cells in the abscission zone

Cytokinesis

reverses the process of leaf abscission and extends the life of the leaf

Response to a herbivore attack

* protinease inhibitors are located within the plant. This is what blocks the protinease enzymes in the mouth and stomach of the herbivores
* the herbivore will get sick
* they learn to detect to avoid the plant tissues which contain high concentrations of the proteins

Systemin

1. the hormone is released from the damaged cells
2. it travels through the phloem membrane receptors and binds to the membrane receptors of the undamaged target cells
3. activated receptors trigger chemical reactions that synthesize the hormone of the jasmonic acid
4. the josmonic acid activates a cyctsolic signaling pathway that induces the production of a suite of the gene products including the proteinase inhibitors