Bacterial Crown Gall

agrobacterium radiobacter

Bacterial Crown Gall is a fascinating and highly consequential plant disease caused by the soil-dwelling bacterium Agrobacterium radiobacter (specifically the pathogenic biovars historically known as Agrobacterium tumefaciens). Known as nature's premier genetic engineer, this single-celled organism possesses the extraordinary ability to naturally transfer a segment of its own DNA directly into the genome of host plants. This horizontal gene transfer reprogrammes the host's cellular machinery to produce swollen, tumor-like growths called galls at the crown or roots, while simultaneously forcing the plant to manufacture specialized nutrients called opines that only the bacteria can digest. While agriculturalists view it as a destructive pest that stunts growth and lowers crop yields in vineyards and orchards, biotechnologists revere it. By replacing the disease-causing genes on its tumor-inducing (Ti) plasmid with beneficial traits, scientists transformed this bacterium into a vital vector for plant genetic engineering.

Habitat: Found globally in agricultural soils, home gardens, and nurseries, particularly in close association with the root systems of susceptible woody and herbaceous plants.

Appearance

While the microscopic bacterial cells themselves are invisible to the naked eye, the infections they cause are easily recognized by the presence of rough, swollen, tumor-like growths called galls. These galls typically develop near the soil line on the plant's crown, main stem, or roots. Initially, the young galls appear as light-colored, soft, fleshy swellings that blend with the plant tissue. As they age, they enlarge significantly, turning dark brown to black, becoming highly woody, cracked, and rough in texture, mimicking natural bark irregularities but in a distinctly globose or irregular form.

KingdomBacteriaPhylumProteobacteriaClassAlphaproteobacteriaOrderRhizobialesFamilyRhizobiaceaeGenusAgrobacterium

Bacterial Crown Gall

Interesting facts

It is often referred to as nature's genetic engineer because it is the only known organism that naturally transfers its genes into a completely different kingdom of life.

Strains of the non-pathogenic bacterium Agrobacterium radiobacter strain K84 are used as a biological control agent to protect crop seeds from infection by pathogenic strains.

The woody tumors (galls) it creates can grow larger than a grapefruit, cutting off the plant's nutrient flow and eventually stunting its growth.

Special abilities

The bacterium transfers a specific segment of DNA, known as T-DNA, from its tumor-inducing plasmid into the genome of a host plant, permanently altering the host's genetic makeup.

It utilizes highly sensitive chemotaxis to detect plant wound signals, such as phenolic compounds, swimming toward damaged roots to initiate infection.

By forcing the host plant to synthesize opines, the bacterium creates an exclusive chemical food source that neighboring soil microbes cannot easily utilize.

Measurements & details

Length: 0+ cm

Diet & Feeding

Feeds primarily on plant-emitted chemical compounds, including specialized nutrient molecules called opines synthesized by infected host plants, along with general organic carbon in the rhizosphere.

Primary Foods

Opines
Plant root exudates
Sugars
Amino acids

Foraging Method

Foraging

Ecological connections

host plant

Wine Grape

Vitis vinifera

Serves as a host plant, where the bacterium causes crown gall disease on stems and roots.

host plant

Peach

Prunus persica

Commonly infected by the bacterium, developing large galls at the graft union or root crown.

host plant

Sweet Briar

Rosa rubiginosa

Infects wild and cultivated roses, creating unsightly galls that weaken the plant's overall vigor.

Traits

Social

Social animals live in organized groups, cooperating for survival benefits such as foraging, defense, and raising offspring.

Colorful

Colorful describes organisms or objects displaying a wide range of bright and distinct colors.

Herbivorous

This trait characterizes organisms whose diet consists entirely or primarily of plant material.

Decomposer

Describes organisms that break down dead organic material, recycling nutrients back into the ecosystem.

Aquatic

Aquatic habitats encompass environments where organisms live predominantly in water, including oceans, rivers, lakes, and wetlands.

Also known as

AgrobacteriumCrown Gall BacteriumGall Bacterium

Collections

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Safety

Danger

1/5 · Very low

No special safety notes yet.

Frequently Asked Questions

How to identify Bacterial Crown Gall?

The easiest way to identify Bacterial Crown Gall is to use the Snappit nature identifier app.

How long is Bacterial Crown Gall?

0+ cm

What does Bacterial Crown Gall eat?

Feeds primarily on plant-emitted chemical compounds, including specialized nutrient molecules called opines synthesized by infected host plants, along with general organic carbon in the rhizosphere.

Where is Bacterial Crown Gall usually found?

Found globally in agricultural soils, home gardens, and nurseries, particularly in close association with the root systems of susceptible woody and herbaceous plants.

How does Bacterial Crown Gall hunt?

Foraging