Plant Growth-promoting Rhizobacteria Provide Greater Control Of Root-knot Nematodes

Bacillus
Suppression of the root-knot nematode [Meloidogyne incognita (Kofoid & White) Chitwood] on tomato by dual inoculation with arbuscular mycorrhizal fungi and plant growth-promoting rhizobacteria.

Arbuscular mycorrhizal (AM) fungi and plant growth-promoting rhizobacteria (PGPR) have potential for the biocontrol of soil-borne diseases. The objectives of this study were to quantify the interactions between AM fungi [Glomus versiforme (Karsten) Berch and Glomus mosseae (Nicol. & Gerd.) Gerdemann & Trappe] and PGPR [Bacillus polymyxa (Prazmowski) Mace and Bacillus sp.] during colonization of roots and rhizosphere of tomato (Lycopersicon esculentum Mill) plants (cultivar Jinguan), and to determine their combined effects on the root-knot nematode, Meloidogyne incognita, and on tomato growth. Three greenhouse experiments were conducted. PGPR increased colonization of roots by AM fungi, and AM fungi increased numbers of PGPR in the rhizosphere. Dual inoculations of AM fungi plus PGPR provided greater control of M. incognita and greater promotion of plant growth than single inoculations, and the best combination was G. mosseae plus Bacillus sp. The results indicate that specific AM fungi and PGPR can stimulate each other and that specific combinations of AM fungi and PGPR can interact to suppress M. incognita and disease development.

STUDY LINK: http://www.ncbi.nlm.nih.gov/pubmed/21755407

Symbiosis: Enforced Surrender?

Symbiosis Enforced Surrender

Scientists from INRA and Lorraine University in France unraveled a key mechanism in the symbiosis between fungi and trees. During this mutually beneficial interaction, the fungus takes control of its host plant by injecting a small protein that neutralizes its immune defenses thereby allowing the fungus to colonize the plant. This finding is a major advance in our understanding of the evolution and functioning of symbiotic interactions between fungi and plants – relationships that play a significant role in supporting the health and sustainability of our natural ecosystems.

In the complex world of the rhizosphere – the soil surrounding plant roots – thousands of species of bacteria and fungi compete for resources released by plants. Some fungi, such as truffles and boletus, are able to live in symbiosis with plants through their roots, by-passing their competitors to obtain sugars directly from their host.  In return, symbiotic fungi allow plant roots to absorb mineral nutrients; this improves the plant’s health, vigor and productivity. Mycorrhizal fungi are one class of symbiotic fungi that make their way to plant roots where they negotiate for housing and all-you-can-eat sugar services. But how does this negotiation play out?  Is the host plant able to distinguish between beneficial and parasitic fungi? How does the fungus avoid the plant’s immune defenses during the interaction?

Continue reading “Symbiosis: Enforced Surrender?”