The application of Science?

 

Case Number 1. Mimics of systemic acquired resistance.

 

A new form of agro-chemical: Elicitors of SAR in the field.

SA is rapidly broken down and is too toxic.

 

 

 

 

 

 

 

 

 

 

 

 

 


In the field the promise of BTH has not been fulfilled for cereal crops.

 

Now targeted use – Mango, Banana, tomato and tobacco.

 


BUT what is the cost –

 

 

 

 

 

 

 

 

 

Also BTH treatment suppresses plant anti-insect measures.

 

Case 2: Protection against insects: BT toxin

 

The Problem:

 

Crop Loss through insect grazing ($ Million)

(% of total crop where known)

 


Cotton                                              1870

Fruit and Vegetables                       2465 (6%)

Rice                                                  1190 (27%)

Maize                                               620 (12%)

Other                                                1965

 

Insecticide Expenditure ($ Million)

 


Rice                                                  45000

Vegetables                                       25000

Fruit                                                 20000

Maize                                               8000

 

 

•Bacillus thuringensis forms toxin crystals (Cry) during sporulation

 

 On injestion by insects, alkaline gut dissolves crystals

 

 Binds to membrane receptors of gut, forming pores, killing the cells.

 

 Large “family” of toxins, which display varied specificity, e.g..

 

lepidoptera, diptera and coleoptera. 

 

Important insect pests e.g. aphids and white fly are immune.

 

Spore and crystal mixture used as pesticide since 1930s, THURICIDE

 

Did not persist, not systemic, too specific

 

Transgenic approach involves introducing the BT gene.

 

Bt expression in chrysanthemum protecting against beet armyworm larvae

 

 

 

 

Problems? – effects of pollen dispersal as shown by work with

  monarch butterflies.