Pathology L3 Bacteria

Question 1

What are the 3 domains

Answer 1

Bacteria, archaea, eukarya

Question 2

2 groups of bacteria

Answer 2

Proteobacteria (purple bacteria), gram-positive bacteria

Question 3

Gram positive bacteria

Answer 3

One layer of cell wall, no outer membrane layer (purple)
Mostly phylum actinobacteria

Question 4

Gram negative bacteria

Answer 4

Thin layer of cell wall, has an outer membrane layer (pink)
Mostly phylum proteobacteria

Question 5

Different shapes of bacteria

Answer 5

Spheres
Pleomophic rods
Spirals
Bacilli (most common)

Question 6

Bacteria reproduce ________ through __________

Answer 6

Asexually, binary fission

Question 7

Biofilm

Answer 7

Groups of bacterial cells that allow bacteria to be visible under magnification

Question 8

How are bacteria disseminated

Answer 8

Wind and rain
Vectors

Question 9

Bacterial spots/blight

Answer 9

Spots on aireal parts of the plant that can smell and ooze
Commonly caused by pseudomonas and xanthomonas

Question 10

PV (pathovar)

Answer 10

Bacterial strain with similar characteristics

Question 11

Canker

Answer 11

Localized dead areas on branches, stems, or roots that are discolored and sunken, as well as smelly and produces a gummy exudate

Question 12

Wilting

Answer 12

Bacteria enter and multiply in vascular tissue, affecting transportation of nutrients and water

Question 13

Symptoms of bacterial infection

Answer 13

Bacterial spot/blight
Canker
Wilting
Gall
Soft rots
Scabs

Question 14

Goss’s wilt

Answer 14

Gram positive bacterial disease of corn caused by clavibacter Michigan ennis nebraskensis
Can overwinter in soil and enter through wounds on the plant

Question 15

Fireblight

Answer 15

Disease of apples and pears that kills branches from canker caused by erwinia amylovora
Overwinters on branches and infects through open flowers

Question 16

Blackleg in potatos

Answer 16

Caused by several bacteria species that are gram negative, necrotrophic, non-sporing, and rod-shaped
Develops Gall, soft rots, and scabs

Question 17

Mollicutes

Answer 17

Major group of small gram-negative plant pathogenic bacteria with only a plasma membrane
Main genera are phytoplasmas and spiroplasmas

Question 18

Spiroplasma shape

Answer 18

Helical

Question 19

Phytoplasma shape

Answer 19

Pleiomorphic or filamentous

Question 20

Where can phytoplasmas and sprioplasmas able to live

Answer 20

Phloem and in some insects vectors

Question 21

How do mollicutes reproduce and spread

Answer 21

Reproduce in plant hosts by binary fission or budding. Spread mainly by insects

Question 22

Corn stunt

Answer 22

Spiroplama disease caused by spiroplasm kukelii and transmitted by corn leafhopper

Question 23

Citrus stubborn disease

Answer 23

Sprioplasma disease caused by spiroplsma citri that infects citrus and some brassica and aster species. Transmitted in budwood and multiple leafhopper sppecies

Question 24

Aster yellows

Answer 24

Phytoplasma disease caused by candidtus phytoplasma asteris

Question 25

What does candidatus mean

Answer 25

It cannot be cultured and thus cannot be properly named

Question 26

Aster yellows symptoms in canola

Answer 26

Phyllody, purpling of pods, blue-green colouration, yield loss

Question 27

Purple top in potatoes

Answer 27

Phytoplasma disease caused by at least 7 distinct strains Symptoms are purple eave, small tubers, aerial tubers, odd hair sprouts

Question 28

Liberibacters

Answer 28

Very similar to phytoplasma and mollicutes

Question 29

Liberibacter diseases

Answer 29

Huanglongbing, potato zebra chip

Question 30

How to identify bacterial diseases

Answer 30

Visual signs and symptoms Observe phenotypes of bacterial cultures Microscopy Serological PCR based signs

Question 31

Types of bactericides

Answer 31

Antibiotics Disinfectants Combinations with fungicides and copper

Question 32

How do we manage proteobacteria

Answer 32

Cultural control Breeding for resistance Destroy vectors (No effective pesticides)