Agrobacterium and Rhizobium (17)

Question 1

Agrobacterium

Answer 1

• parasitism
• Tumors in plants from bacterial infection at wound site
• transfer of DNA inter-kingdom

Question 2

Rhizobia

Answer 2

• Mutulaism
• root nodules and N2 fixers (make A.A.’s)
• form on legumenous plants (clover, soybeans etc.)

Question 3

Agrobacteria Plasmid

Answer 3

• vir genes (tra genes but virulant), code for transfer of DNA
• transfer DNA, goes into plant

Question 4

Agrobacteria Signaling

Answer 4

• Sensor Kinase & response regulator
• recognizes when wound on plant
• proteins encoded from plasmid up transcription for Tra genes
• single stranded binding protects it through into plant nucleus

Question 5

Tumor genes

Answer 5

Oncogenes - production of auxin and cytotoxins, cell devision, make tumor
Opines - A.A. like compounds plant produces, food for agrobacteria (and only agrobacteria)

Question 6

Root Nodules

Answer 6

• Red colour

- hemoglobin, binds to oxygen (keeps away from nitrogenase)

Question 7

Biovar

Answer 7

What type of association, plant type it associates with.

Question 8

Nitrogen Fixation

Answer 8

Nitrogen gas put into amino acids.

• Lots of ATP required.
• sensitive to oxygen

Question 9

Steps of Infection Rhizobia

Answer 9

1. Root hairs (send flavanoids) are infected,
2. cyclic B-1,2 glucans make it stick.
3. nod factors produced by bacteria
4. plant curls hair, lets in specific matching bacteria
5. move along thread, grow, devide, differentate
6. become Bacteroid (fix nitrogen)

Question 10

Bacteroids

Answer 10

Plant makes sugars, converted to organic acids.
1. Makes ATP from acids.
2. pruvate able to provide electrons for nitrogenase
Oxygen mopped by leghemoglobin.
PHB granules from extra carbon

Question 11

NodD

Answer 11

activated by plant flavanoids and increas transcription of nod genes and nitrogen fixation genes.

Question 12

NodA,B,C

Answer 12

Make nod factors, send signal to plant, induces root curling.

Question 13

Node,f,l,m

Answer 13

Modify the nod factors to customize for specificity.

Question 14

NodI,J

Answer 14

Export message to plant.

Question 15

Specificity of Nod Factors

Answer 15

Lipids, chitin and sugar.
lipochitooligosaccharides
(NAG, NAG, NAG)
Also get R-groups for specificity custom for the plant.

Question 16

Specificity of Flavonoids

Answer 16

Common in fruits of plants, roots.

Inducer and inhibitor flavanoids. To get the type of rhizobia they want.

Question 17

Infection of Agrobacterium

Answer 17

1. Wounding required.
   2a. Attachment of Agrobacterium to plant cells.
   2b. vir gene induction in response to signals from plant (phenolics, monosaccharides, acidic pH)
2. T-DNA processing.
3. T-DNA transfer into plant cell.
4. Integration of T-DNA into plant nuclear genome and expression of genes.
5. Tumour formation, opine synthesis.