1-Aminocyclopropane-1-carboxylate deaminase producers associated to maize and other Poaceae species

Abstract

BackgroundComplex plant-microbe interactions have been established throughout evolutionary time, many of them with beneficial effects on the host in terms of plant growth, nutrition, or health. Some of the corresponding modes of action involve a modulation of plant hormonal balance, such as the deamination of the ethylene precursor 1-aminocyclopropane-1-carboxylate (ACC). Despite its ecological importance, our understanding of ACC deamination is impaired by a lack of direct molecular tools. Here, we developed PCR primers to quantify the ACC deaminase gene acdS and its mRNA in soil communities and assessed acdS+ microorganisms colonizing maize and other Poaceae species.ResultsEffective acdS primers suitable for soil microbial communities were obtained, enabling recovery of bona fida acdS genes and transcripts of diverse genetic backgrounds. High numbers of acdS genes and transcripts were evidenced in the rhizosphere of Poaceae, and numbers fluctuated according to plant genotype. Illumina sequencing revealed taxonomic specificities of acdS+ microorganisms according to plant host. The phylogenetic distance between Poaceae genotypes correlated with acdS transcript numbers, but not with acdS gene numbers or the genetic distance between acdS functional groups.ConclusionThe development of acdS primers enabled the first direct analysis of ACC deaminase functional group in soil and showed that plant ability to interact with soil-inhabiting acdS+ microorganisms could also involve particular plant traits unrelated to the evolutionary history of Poaceae species.Electronic supplementary materialThe online version of this article (10.1186/s40168-018-0503-7) contains supplementary material, which is available to authorized users.

Deciphering the Root Endosphere Microbiome of the Desert Plant Alhagi sparsifolia for Drought Resistance-Promoting Bacteria

“…The drought resistance-promoting strain LTGT-11-2Z possesses broad PGP potential, as revealed by comparative genome analysis. Siderophore production is a well-known PGP property (38); polyamine production may contribute to the improvement of plant growth under water stress conditions (39); and lowering plant ethylene levels through ACC deaminase activity is among the major mechanisms employed by PGP bacteria to protect plants against a wide range of environmental stresses (40,41). LTGT-11-2Z also possesses genes responsible for flagellum biosynthesis, chemotaxis, curli fiber production, and plant cell wall-degrading enzymes, which may be involved in plant adhesion and colonization (24,27).…”

Microbial Diversity of Upland Rice Roots and Their Influence on Rice Growth and Drought Tolerance

“…Isolates were spot inoculated on DF salt minimal agar media [ 6 , 59 ] supplemented with 3 mM ACC instead of (NH 4 ) 2 SO 4 as a N source, after which the presence of the ACC deaminase gene acdS was determined [ 60 , 61 , 62 ]. The acdS gene was amplified by PCR using the degenerate primers acdSf3 (5′-ATCGGCGGCATCCAGWSNAAYCANAC-3′) and acdSr4 (5′-GGCACGCCGCCCARRTGNRCRTA-3′) [ 29 , 63 , 64 ].…”

“…It has been verified that certain bacteria are able to produce ACC deaminase to convert the ethylene precursor ACC into α-ketobutyrate and ammonia [ 25 ]. By degrading ACC within roots or in exudates [ 26 ], root-interacting bacteria can reduce ethylene levels in plant roots [ 27 , 28 ], stimulate root growth and improve plant drought tolerance [ 29 , 30 ]. The production of exopolysaccharides (EPS) also plays an important role in supporting plant growth under drought-stress conditions [ 14 , 16 , 31 ].…”

Biocontrol of Cereal Crop Diseases Using Streptomycetes

“…In the future, there is a crucial need for carefully designed experiments that investigate whether the application of antagonistic biocontrol strains can have a long-term influence on pathogen populations, the functionality of the soil microbiome and key environmental processes [189]. Studies could be informed by monitoring the abundance of important indicator species, such as mycorrhiza, which contribute to plant health and nutrient cycling [189], or the expression of indicative functional genes that are related to plant-beneficial processes, including enzymes involved in PGP such as 1-aminocyclopropane-1-carboxylate (ACC) deaminase [209], or mycorrhizal-inducible phosphate transporters, which have been identified in several different cereal plants [210,211]. Careful controls will also be needed to differentiate between the influence of antagonistic molecules produced by inoculated streptomycete species on the soil microbiome, versus other factors such as biocontrol formulation components and abiotic changes [189].…”