Bacillus firmus Strain I-1582, a Nematode Antagonist by Itself and Through the Plant

Abstract

Bacillus firmus I-1582 is approved in Europe for the management of Meloidogyne on vegetable crops. However, little information about its modes of action and temperature requirements is available, despite the effect of these parameters in its efficacy. The cardinal temperatures for bacterial growth and biofilm formation were determined. The bacteria was transformed with GFP to study its effect on nematode eggs and root colonization of tomato (Solanum lycopersicum) and cucumber (Cucumis sativus) by laser-scanning confocal microscopy. Induction of plant resistance was determined in split-root experiments and the dynamic regulation of genes related to jasmonic acid (JA) and salicylic acid (SA) by RT-qPCR at three different times after nematode inoculation. The bacteria was able to grow and form biofilms between 15 and 45 • C; it degraded eggshells and colonized eggs; it colonized tomato roots more extensively than cucumber roots; it induced systemic resistance in tomato, but not in cucumber; SA and JA related genes were primed at different times after nematode inoculation in tomato, but only the SA-related gene was up-regulated at 7 days after nematode inoculation in cucumber. In conclusion, B. firmus I-1582 is active at a wide range of temperatures; its optimal growth temperature is 35 • C; it is able to degrade Meloidogyne eggs, and to colonize plant roots, inducing systemic resistance in a plant dependent species manner.

Bacillus firmus I-1582 promotes plant growth and impairs infection and development of the cyst nematode Heterodera schachtii over two generations

“… Microscopic observations during the reported study showed that the bacterium colonizes the root system building layers of bacterial cells along the root. This is in accordance with a recent study documenting B. firmus biofilm formation and colonization of tomato and cucumber roots 59 . Thus, it might be that the bacterium constitutes a physical barrier protecting the plant from nematode invasion.…”

Tomato and Melon Meloidogyne Resistant Rootstocks Improve Crop Yield but Melon Fruit Quality Is Influenced by the Cropping Season

“…However, the occurrence of abiotic and/or biotic stresses and its intensity during a given phenological stage of the plant can lead to changes in fruits and vegetables quality such as an increase of bioactive compounds ( Nicoletto et al, 2019 ; Toscano et al, 2019 ). Interestingly, there is a crossing-talk between signaling pathways allowing plant plasticity to be adapted to environmental situations ( Martinez-Medina et al, 2017 ; Ghahremani et al, 2020 ). Atkinson et al (2011) studied the effect of water stress and M. incognita (10 eggs g –1 soil) alone and in combination on the nutritional fruit quality of tomato cv.…”

Biocontrol of the root‐knot nematodeMeloidogyne incognitaby a nematicidal bacteriumPseudomonas simiaeMB751with cyclic dipeptide

“…To evaluate the resistance inducibility of MB751 in tomato against M. incognita , a split‐root experiment was conducted 25,26 . Three pots 13 cm diameter × 12 cm deep were filled with sterile soil (~10.0 cm depth in each pot, ~1.0 kg soil).…”