Stimulation of Defense Reactions in Medicago truncatula by Antagonistic Lipopeptides from Paenibacillus sp. Strain B2

Abstract

With the aim of obtaining new strategies to control plant diseases, we investigated the ability of antagonistic lipopolypeptides (paenimyxin) from Paenibacillus sp. strain B2 to elicit hydrogen peroxide (H 2 O 2 ) production and several defense-related genes in the model legume Medicago truncatula. For this purpose, M. truncatula cell suspensions were used and a pathosystem between M. truncatula and Fusarium acuminatum was established. In M. truncatula cell cultures, the induction of H 2 O 2 reached a maximum 20 min after elicitation with paenimyxin, whereas concentrations higher than 20 M inhibited H 2 O 2 induction and this was correlated with a lethal effect. In plant roots incubated with different concentrations of paenimyxin for 24 h before inoculation with F. acuminatum, paenimyxin at a low concentration (ca. 1 M) had a protective effect and suppressed 95% of the necrotic symptoms, whereas a concentration higher than 10 M had an inhibitory effect on plant growth. Gene responses were quantified in M. truncatula by semiquantitative reverse transcription-PCR (RT-PCR). Genes involved in the biosynthesis of phytoalexins (phenylalanine ammonia-lyase, chalcone synthase, chalcone reductase), antifungal activity (pathogenesis-related proteins, chitinase), or cell wall (invertase) were highly upregulated in roots or cells after paenimyxin treatment. The mechanisms potentially involved in plant protection are discussed.

An Extract Purified from the Mycelium of a Tomato Wilt-Controlling Strain of Fusarium sambucinum Can Protect Wheat against Fusarium and Common Root Rots

“…B. sorokiniana ) at micromolar concentrations [56,58]. In addition, data presented here confirm results of other authors showed the role defensins in protection of wheat and other plants against root diseases that are inefficiently controlled by fungicides [31,32]. Thus, we can expect that gene expression of these defensive peptides in seedlings grown from PME-treated seeds might also contribute to wheat protection against root rot causative agents under field conditions.…”

“…Seed treatments with biocontrol microorganisms or their biomolecules conjointly with other management procedures (healthy seeds, resistant cultivars, rotation with appropriate non-host crops, correct selection of fertilizers) might be an approach for improving the systems of integrated wheat protection from FCR and CRR without increasing the chemical impact in cereal-growing regions [19]. To implement this approach, biocontrol microorganisms, potential biopesticides or resistance inducers, which would effectively reduce the diseases on wheat plants after application on seeds should be available [31,32]. Several years ago, we discovered that F. sambucinum FS-94 induced systemic resistance to the vascular wilt of tomato [33], and briefly reported the inhibition of some rot- or blotch-causing wheat pathogens by the metabolites of this fungus under controlled and field conditions [34,35].…”

Cyclic Lipopeptides from Bacillus subtilis ABS–S14 Elicit Defense-Related Gene Expression in Citrus Fruit

“…The mechanisms of action of iturin A, fengycin and surfactin involved in plant protection as elucidated in this work were somewhat similar to those of lipopaenimyxin [35] in that they activated genes that encoded for proteins that responded to the external stimuli: such as cell wall proteins, defense and cell rescue, lipid-related signaling, membrane transport, oxidative stress, phenylpropanoid and phytoalexin pathways, primary metabolism, protein synthesis and their processing in a legume cell suspension. Furthermore, PR1 , PR2 , and PR5 and the jasmonic acid-responsive gene ( vsp ) have been reported to respond to ultrashort lipopeptides in Arabidopsis [36] .…”

Controlling and Defence‐related Mechanisms of Bacillus Strains Against Bacterial Leaf Blight of Rice

“…The mechanisms for plant protection of iturin A, fengycin and surfactin were similar to those of lipopaenimyxin to some extent. Selim et al (2010) found that the activated genes encoded for protein function were responding to the external stimuli, such as cell wall proteins, defence and cell rescue, lipid-related signalling, membrane transport, oxidative stress, phenylpropanoid and phytoalexin pathways, primary metabolism, protein synthesis and their processing in a legume cell suspension. These results will emphasized that the suggested mechanism for antimicrobial activity of strains A15 and D29 and Bacillus strains is owing to the higher expression levels of these genes consequently their potential ability to secrete corresponding lipopeptides in surrounding niches (Raaijmakers et al 2010;Xu et al 2013).…”