Growth promotion of Lactuca sativa in response to volatile organic compounds emitted from diverse bacterial species

Abstract

Agrochemicals are currently used in horticulture to increase crop production. Nevertheless, their indiscriminate use is a relevant issue for environmental and legal aspects. Alternative tools for reducing fertilizers and synthetic phytohormones are being investigated, such as the use of volatile organic compounds (VOCs) as growth inducers. Some soil bacteria, such as Pseudomonas and Bacillus, stimulate Arabidopsis and tobacco growth by releasing VOCs, but their effects on vegetables have not been investigated. Lactuca sativa was used as model vegetable to investigate bacterial VOCs as growth inducers. We selected 10 bacteria strains, belonging to Bacillus, Staphylococcus and Serratia genera that are able to produce 3-hydroxy-2-butanone (acetoin), a compound with proven growth promoting activity. Two-day old-seedlings of L. sativa were exposed to VOCs emitted by the selected bacteria grown in different media cultures for 7 days. The results showed that the VOCs released from the bacteria elicited an increase in the number of lateral roots, dry weight, root growth and shoot length, depending on the media used. Three Bacillus strains, BCT53, BCT9 and BCT4, were selected according to its their growth inducing capacity. The BCT9 strain elicited the greatest increases in dry weight and primary root length when L. sativa seedlings were subjected to a 10-day experiment. Finally, because acetoin only stimulated root growth, we suggest that other volatiles could be responsible for the growth promotion of L. sativa. In conclusion, our results strongly suggest that bacteria volatiles can be used as growth-inducers as alternative or complementary strategies for application in horticulture species.

Volatile Compounds From Bacillus, Serratia, and Pseudomonas Promote Growth and Alter the Transcriptional Landscape of Solanum tuberosum in a Passively Ventilated Growth System

“…For transcriptomic analysis of potato plants exposed to BVCs in our system the isolates LAC2 and the commercially available isolate FZB24, members of Serratia and Bacillus respectively were chosen as the BVC source due to the fact they only share two common BVCs when grown on MR-VP, namely 2-piperidinone and hexadecane. Additionally, species of these genus have been well documented to emit antimicrobial and growth-promoting BVCs ( Fincheira et al, 2016 ; Tahir et al, 2017 ). Therefore, we expected to see noticeable alterations in the plant transcriptomic landscape in response to these isolates.…”

Fusaricidins, Polymyxins and Volatiles Produced by Paenibacillus polymyxa Strains DSM 32871 and M1

“…Acetoin, 2,3-butanediol and 3-methyl-1-butanol can be found in the volatilomes of DSM 32871 and M1. These compounds are known for their plant growth promoting effect and induce systemic resistance (ISR) in distinct plants [43,47,[58][59][60][61]. Examples for medium specificity included 2,3-butanediol which was formed by both strains only in the Landy medium, while 1-octen-3-ol and 2-ethyl-1-hexanol have been detected specifically in the TSA-medium.…”

Volatile organic compounds stimulate plant growing and seed germination of Lactuca sativa

“…According to the methodology reported by Fincheira et al (2016), bioassays were performed in two-compartment Petri dishes (90 x 15 mm) with 8 CFU mL -1 ). The plates were distributed in a randomized design and non-inoculated plates were used as control (Blom et al, 2011;Velázquez-Becerra et al, 2011).…”