Identification of Volatile Organic Compounds Emitted by Two Beneficial Endophytic Pseudomonas Strains from Olive Roots

Abstract

The production of volatile organic compounds (VOCs) represents a promising strategy of plant-beneficial bacteria to control soil-borne phytopathogens. Pseudomonas sp. PICF6 and Pseudomonas simiae PICF7 are two indigenous inhabitants of olive roots displaying effective biological control against Verticillium dahliae. Additionally, strain PICF7 is able to promote the growth of barley and Arabidopsis thaliana, VOCs being involved in the growth of the latter species. In this study, the antagonistic capacity of these endophytic bacteria against relevant phytopathogens (Verticillium spp., Rhizoctonia solani, Sclerotinia sclerotiorum and Fusarium oxysporum f.sp. lycopersici) was assessed. Under in vitro conditions, PICF6 and PICF7 were only able to antagonize representative isolates of V. dahliae and V. longisporum. Remarkably, both strains produced an impressive portfolio of up to twenty VOCs, that included compounds with reported antifungal (e.g., 1-undecene, (methyldisulfanyl) methane and 1-decene) or plant growth promoting (e.g., tridecane, 1-decene) activities. Moreover, their volatilomes differed strongly in the absence and presence of V. dahliae. For example, when co incubated with the defoliating pathotype of V. dahliae, the antifungal compound 4-methyl-2,6-bis(2-methyl-2-propanyl)phenol was produced. Results suggest that volatiles emitted by these endophytes may differ in their modes of action, and that potential benefits for the host needs further investigation in planta.

Volatiles from Pseudomonas palleroniana Strain B-BH16-1 Suppress Aflatoxin Production and Growth of Aspergillus flavus on Coix lacryma-jobi during Storage

“…Previous research has found that 1-undecene and squalene have antifungal and antinematode activities able to control soil-borne plant diseases. For instance, 1-undecene produced by P. chlororaphis and P. fluorescens have inhibitory activities on Colletotrichum dematium , C. gloeosporioides , Fusarium oxysporum , F. subglutinans and Stemphylium lycopersici in many plants, such as potato [ 34 ], maize [ 35 ], citrus [ 36 ], and olive [ 37 ]. In addition, squalene and 1-undecene can be used as a preservative for TCM and food/feed, because they have the ability to inhibit mold growth [ 38 , 39 ].…”

Recent Advances in the Bacterial Phytohormone Modulation of Plant Growth

“…While they are not considered to be phytohormones per se, the volatile organic compounds (VOCs) that are synthesized by a wide range of soil bacteria have recently been shown to play a significant role in plant growth promotion [ 6 , 31 , 32 , 33 , 34 ]. The growth promotion effect of VOCs is largely attributed to the modulation of the synthesis and/or metabolism of known phytohormones, synthesized by either PGPB or by plants [ 35 , 36 ].…”

Identification and Surveys of Promoting Plant Growth VOCs from Biocontrol Bacteria Paenibacillus peoriae GXUN15128

“…However, in the study of plant growth-promoting functions of VOCs, VOCs cannot be used as the main criterion to evaluate the beneficial bacteria or that the VOCs of plant pathogens can also promote plant growth ( 33 ). The production of VOCs by Pseudomonas aeruginosa Picf7 isolated from olive root can promote the growth of barley and Arabidopsis thaliana ( 34 ), VOCs produced by Rhizoctonia solani can promote the growth of A. thaliana seedlings and adult seedlings ( 35 ), VOCs produced by Botrytis cinerea QT5-19 could promote the growth of tomato ( 36 ), and VOCs produced by Alternaria alternata promote the growth and flowering of A. thaliana ( 37 ). Although pathogens can also have VOCs that have plant growth-promoting functions, studies of VOC growth-promoting functions based on beneficial bacteria have broader application prospects and have become the focus of MVOC research ( 38 – 44 ).…”