Question

The bacteria most commonly associated with the soft rotting of carrots is

• A. Corynebacterium spp.
• B. Lactobacillus spp.
• C. Pectobacterium spp.
• D. Xanthomonas spp.

Hint:

Remember the connection between the name and function: \textbf{Pecto}bacterium breaks down \textbf{pectin}, the glue holding plant cells together. This breakdown is what causes the characteristic "soft rot" symptom.

Answer 1

The Correct Option is C

Step 1: Define bacterial soft rot. This is a type of plant disease characterized by the breakdown and decay of plant tissues, resulting in a soft, watery, and often foul-smelling mass.

Step 2: Analyze the causative agents. The primary cause of this type of rot is the production of pectinolytic enzymes (pectinases) by bacteria, which break down the pectin that cements plant cells together.

Step 3: Evaluate the bacterial genera listed.
Pectobacterium spp.: This genus (which includes species formerly classified as Erwinia) is the most notorious and widespread cause of bacterial soft rot in numerous vegetables, including carrots. Pectobacterium carotovorum is a classic example. They are highly effective at producing pectinases.
Lactobacillus spp.: These are lactic acid bacteria used in fermentation and are not associated with plant disease.
Xanthomonas spp.: These are plant pathogens but typically cause different symptoms like leaf spots, blights, and cankers, not soft rot.
Corynebacterium spp.: While some species are plant pathogens, they are not the primary agents of soft rot.
Therefore, Pectobacterium is the genus most commonly associated with soft rot.