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Plant Pathogens (GATE)

Description: Proteins
Number of Questions: 15
Created by:
Tags: Bacteria and Viruses Botany Pathology Plants Bacteria and Viruses and Their Control Measures
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D-threo-aldose 1- dehydrogenase oxidises glucose. Which of the following plant pathogens produces enzyme D-threo-aldose 1- dehydrogenase?

  1. Burkholderia caryophylli

  2. Burkholderia cepacia

  3. Burkholderia gladioli

  4. Burkholderia glumae


Correct Option: A
Explanation:

Burkholderia caryophylli causes bacterial wilt. It is known to contain enzyme D-threo-aldose 1-dehydrogenase, which allows it to oxidise L-glucose.

Bacterial fruit blotch (BFB) affects cucurbit plants around the world. Which of the following bacteria is implicated in this disease?

  1. Acidovorax cattleyae

  2. Acidovorax citrulli

  3. Acidovorax konjaci

  4. Acidovorax avenae ssp. avenae


Correct Option: B
Explanation:

Acidovorax citrulli infection can result in bacterial fruit blotch (BFB). Lesions are necrotic and may be located near veins. The fruit eventually decays and cracks when the pathogen causes necrosis.

Burkholderia glumae is a Gram-negative soil bacterium. Which of the following diseases is caused by it?

  1. Leaf blight of grass

  2. Southern leaf blight in corn

  3. Bacterial leaf blight of rice

  4. Bacterial panicle blight of rice


Correct Option: D
Explanation:

Correct Answer: Bacterial panicle blight of rice

Phytoplasma antigenic protein interacts with which of the following?

  1. Endoplasmic reticulum

  2. Spindle fibers

  3. Microfilament complex

  4. Cytoplasmic membrane


Correct Option: C
Explanation:

Phytoplasma antigenic protein has been shown to interact with insect microfilament complexes. It is believed to be the determining factor in insect-phytoplasma interaction.

Which of the following bacteria produces unique red pigment that has been hypothesised to play a role in the pathogenesis of walnut?

  1. Brenneria salicis

  2. Brenneria populi

  3. Brenneria rubrifaciens

  4. Brenneria nigrifluens


Correct Option: C
Explanation:

Brenneria rubrifaciens produces a unique red pigment (rubrifacine) that has been hypothesised to play a role in pathogenesis of walnut.

Clavibacter michiganensis subsp. sepedonicus causes ring rot in potatoes. It resides in which of the following during the first stage of invasion?

  1. Plant leaves

  2. Xylem vessels

  3. Phloem vessels

  4. Parenchymatous tissue


Correct Option: B
Explanation:

In the first stages of invasion, Clavibacter michiganensis resides as a biotrophic pathogen in the xylem vessels. They multiply by binary fission inside the vessel and establish colony there. If colonisation is successful, they may plug the xylem vessels.

Dickeya dadantii causes necrosis, blight and soft rot of several different ornamental and horticultural host plants. Which of the following enzymes does it contain to macerate and break down the plant material?

  1. Pectinase

  2. Cellulase

  3. Hyaluronidase

  4. Oxidase


Correct Option: A
Explanation:

Dickeya dadantii contains many pectinases that are able to macerate and break down the plant cell wall material. This exposed part of the plant releases nutrients that can facilitate bacterial growth.

Curtobacterium flaccumfaciens is a Gram-positive soil bacterium that causes disease in plants. Which of the following diseases are caused by it in soybean?

a. Bacterial tan spot b. Bacterial pustules c. Bacterial blight d. Bacterial wilt

  1. Only a and b

  2. Only a and d

  3. Only a, c and d

  4. Only b and c


Correct Option: B
Explanation:

Bacterial wilt and bacterial tan spot are caused by Curtobacterium flaccumfaciens pv. flaccumfaciens.

Which of the following bacteria causes stunting and wilting of alfalfa?

  1. Clavibacter michiganensis subsp. insidiosus

  2. Clavibacter michiganensis subsp. tesselarius

  3. Clavibacter michiganensis subsp. nebraskensis

  4. Clavibacter michiganensis subsp. michiganensis


Correct Option: A
Explanation:

Clavibacter michiganensis subsp. insidiosus causes wilting and stunting in alfalfa.

Ratoon stunting disease is associated with which of the following pairs of pathogen and plant?

  1. Leifsonia xyli xyli - bermuda grass

  2. Leifsonia xyli cynodontis - bermuda grass

  3. Leifsonia xyli cynodontis - sugarcane plant

  4. Leifsonia xyli xyli - sugarcane plant


Correct Option: D
Explanation:

Leifsonia xyli subsp. xyli is a small, fastidious, Gram-positive and coryneform bacterium that is associated with the ratoon stunting disease, a major worldwide disease of sugarcane. Infected plants show reduced cane diameter and shortening of the inter-nodes.

Enterobacter cloacae is associated with normal gut flora of humans. What does it cause in liliac plants?

  1. Bacterial rot

  2. Bacterial wet wood

  3. Bulb decay

  4. Bacterial wilt


Correct Option: C
Explanation:

Enterobacter bulb decay is a recently described storage disease of onion (Allium cepa), member of liliaceae family that is caused by Enterobacter cloacae. The disease was reported in 2011. In this disease, the exterior of the bulb remains asymptomatic while the inner scales show a brown to black discoloration and decay.

Agrobacterium tumefaciens is a serious pathogen that causes crown gall disease. To initiate an infection, it needs to transfer t-DNA into the plant cell. Which of the following secretion mechanisms is used by it to transfer t-DNA?

  1. Type IV secretion mechanism

  2. Type III secretion mechanism

  3. Type II secretion mechanism

  4. Type I secretion mechanism


Correct Option: A
Explanation:

To transfer t-DNA into the plant cell, A. tumefaciens uses a type IV secretion mechanism that involves the production of a T-pilus.

Blackleg of potato is the typical blackening and decay of the lower stem portion of plant. Which of the following bacteria causes blackleg of potato?

  1. Pectobacterium carotovorum

  2. Pectobacterium betavasculorum

  3. Pectobacterium atrosepticum

  4. Pectobacterium chrysanthemi


Correct Option: C
Explanation:

Blackleg in potatoes is caused by Pectobacterium atrosepticum. It results in stunting, wilting, chlorosis of leaves, necrosis of several tissues, a decline in yield and the death of the potato plant.

Which of the following plant pathogens can be commercially exploited to obtain 6-Amino penicillanic acid (6-APA)?

  1. Pseudomonas citronellolis

  2. Pseudomonas cichorii

  3. Pseudomonas asplenii

  4. Pseudomonas marginalis


Correct Option: B
Explanation:

Pseudomonas cichorii is a Gram-negative soil bacterium that is pathogenic to lettuce, celery and chrysanthemum crops. It produces 6-aminopenicillanic acid that forms the core of penicillin. It shows the possibility of being commercially exploited for obtaining 6-Amino penicillanic acid.

Which of the following is injected into apple and pear plants to prevent fire blight disease caused by Erwinia amylovora?

  1. Oxacillin

  2. Streptomycin

  3. Tetracycline

  4. Oxytetracycline


Correct Option: D
Explanation:

There is no known cure for fire blight. Disease can be prevented by injecting plants with oxytetracycline.

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