The class IId bacteriocin thuricin-17 increases plant growth

Area of Science:

• Microbiology
• Plant Science
• Biochemistry

Background:

• Plant growth-promoting rhizobacteria (PGPR) mechanisms remain largely unknown.
• Bacillus thuringiensis NEB17, a rhizosphere bacterium, was isolated for its soybean growth promotion.
• This bacterium produces a novel bacteriocin, thuricin-17 (class IId).

Purpose of the Study:

• To investigate the plant growth-stimulating properties of thuricin-17.
• To determine if thuricin-17 directly affects plant growth.
• To explore the evolutionary implications of thuricin-17's dual functions.

Main Methods:

• Isolated Bacillus thuringiensis NEB17 and screened its growth medium for plant growth factors.
• Applied purified thuricin-17 to soybean (C3 dicot) and corn (C4 monocot) via leaf spray and root drench.
• Analyzed the gene copies for thuricin-17 in strain NEB17.

Main Results:

• Thuricin-17 directly stimulated the growth of both soybean and corn plants.
• The observed growth stimulation was comparable to Nod factor treatments.
• Strain NEB17 possesses three identical gene copies for thuricin-17.

Conclusions:

• Bacteriocins, like thuricin-17, can directly enhance plant growth.
• This finding represents the first report of direct plant growth enhancement by a bacteriocin.
• The conserved nature of thuricin-17 suggests evolutionary constraints due to its dual functions.