scholarly journals Tryptophan metabolism and bacterial commensals prevent fungal dysbiosis in Arabidopsis roots

2021 ◽  
Vol 118 (49) ◽  
pp. e2111521118
Author(s):  
Katarzyna W. Wolinska ◽  
Nathan Vannier ◽  
Thorsten Thiergart ◽  
Brigitte Pickel ◽  
Sjoerd Gremmen ◽  
...  

In nature, roots of healthy plants are colonized by multikingdom microbial communities that include bacteria, fungi, and oomycetes. A key question is how plants control the assembly of these diverse microbes in roots to maintain host–microbe homeostasis and health. Using microbiota reconstitution experiments with a set of immunocompromised Arabidopsis thaliana mutants and a multikingdom synthetic microbial community (SynCom) representative of the natural A. thaliana root microbiota, we observed that microbiota-mediated plant growth promotion was abolished in most of the tested immunocompromised mutants. Notably, more than 40% of between-genotype variation in these microbiota-induced growth differences was explained by fungal but not bacterial or oomycete load in roots. Extensive fungal overgrowth in roots and altered plant growth was evident at both vegetative and reproductive stages for a mutant impaired in the production of tryptophan-derived, specialized metabolites (cyp79b2/b3). Microbiota manipulation experiments with single- and multikingdom microbial SynComs further demonstrated that 1) the presence of fungi in the multikingdom SynCom was the direct cause of the dysbiotic phenotype in the cyp79b2/b3 mutant and 2) bacterial commensals and host tryptophan metabolism are both necessary to control fungal load, thereby promoting A. thaliana growth and survival. Our results indicate that protective activities of bacterial root commensals are as critical as the host tryptophan metabolic pathway in preventing fungal dysbiosis in the A. thaliana root endosphere.

2013 ◽  
Vol 26 (5) ◽  
pp. 546-553 ◽  
Author(s):  
Ana Zúñiga ◽  
María Josefina Poupin ◽  
Raúl Donoso ◽  
Thomas Ledger ◽  
Nicolás Guiliani ◽  
...  

Although not fully understood, molecular communication in the rhizosphere plays an important role regulating traits involved in plant–bacteria association. Burkholderia phytofirmans PsJN is a well-known plant-growth-promoting bacterium, which establishes rhizospheric and endophytic colonization in different plants. A competent colonization is essential for plant-growth-promoting effects produced by bacteria. Using appropriate mutant strains of B. phytofirmans, we obtained evidence for the importance of N-acyl homoserine lactone-mediated (quorum sensing) cell-to-cell communication in efficient colonization of Arabidopsis thaliana plants and the establishment of a beneficial interaction. We also observed that bacterial degradation of the auxin indole-3-acetic acid (IAA) plays a key role in plant-growth-promoting traits and is necessary for efficient rhizosphere colonization. Wildtype B. phytofirmans but not the iacC mutant in IAA mineralization is able to restore promotion effects in roots of A. thaliana in the presence of exogenously added IAA, indicating the importance of this trait for promoting primary root length. Using a transgenic A. thaliana line with suppressed auxin signaling (miR393) and analyzing the expression of auxin receptors in wild-type inoculated plants, we provide evidence that auxin signaling in plants is necessary for the growth promotion effects produced by B. phytofirmans. The interplay between ethylene and auxin signaling was also confirmed by the response of the plant to a 1-aminocyclopropane-1-carboxylate deaminase bacterial mutant strain.


Author(s):  
Di Fan ◽  
Donald L. Smith

There are pressing needs to reduce the use of agrochemicals, and PGPR are receiving increasing interest in plant growth promotion and disease protection. This study follows up our previous report that the four newly isolated rhizobacteria promote the growth of Arabidopsis thaliana .


2019 ◽  
Vol 85 (19) ◽  
Author(s):  
Evan Mayer ◽  
Patricia Dörr de Quadros ◽  
Roberta Fulthorpe

ABSTRACT A collection of bacterial endophytes isolated from stem tissues of plants growing in soils highly contaminated with petroleum hydrocarbons were screened for plant growth-promoting capabilities. Twenty-seven endophytic isolates significantly improved the growth of Arabidopsis thaliana plants in comparison to that of uninoculated control plants. The five most beneficial isolates, one strain each of Curtobacterium herbarum, Paenibacillus taichungensis, and Rhizobium selenitireducens and two strains of Plantibacter flavus were further examined for growth promotion in Arabidopsis, lettuce, basil, and bok choy plants. Host-specific plant growth promotion was observed when plants were inoculated with the five bacterial strains. P. flavus strain M251 increased the total biomass and total root length of Arabidopsis plants by 4.7 and 5.8 times, respectively, over that of control plants and improved lettuce and basil root growth, while P. flavus strain M259 promoted Arabidopsis shoot and root growth, lettuce and basil root growth, and bok choy shoot growth. A genome comparison between P. flavus strains M251 and M259 showed that both genomes contain up to 70 actinobacterial putative plant-associated genes and genes involved in known plant-beneficial pathways, such as those for auxin and cytokinin biosynthesis and 1-aminocyclopropane-1-carboxylate deaminase production. This study provides evidence of direct plant growth promotion by Plantibacter flavus. IMPORTANCE The discovery of new plant growth-promoting bacteria is necessary for the continued development of biofertilizers, which are environmentally friendly and cost-efficient alternatives to conventional chemical fertilizers. Biofertilizer effects on plant growth can be inconsistent due to the complexity of plant-microbe interactions, as the same bacteria can be beneficial to the growth of some plant species and neutral or detrimental to others. We examined a set of bacterial endophytes isolated from plants growing in a unique petroleum-contaminated environment to discover plant growth-promoting bacteria. We show that strains of Plantibacter flavus exhibit strain-specific plant growth-promoting effects on four different plant species.


2005 ◽  
Vol 268 (1) ◽  
pp. 285-292 ◽  
Author(s):  
Choong-Min Ryu ◽  
Chia-Hui Hu ◽  
Robert D. Locy ◽  
Joseph W. Kloepper

2014 ◽  
Vol 65 (1) ◽  
pp. 71-77
Author(s):  
Ghazala Nasim ◽  
Sobia Mushtaq ◽  
Irum Mukhtar ◽  
Ibatsam Khokhar

AbstractPenicilliumspp. are well known to produce a variety of beneficial metabolites for plant growth and survival, as well as defend their hosts from attack of certain pathogens. In this study, effects of culture filtrate of differentPenicilliumspp. were tested on tomato seeds. On the whole, presoaking of seeds in filtrates of the ninePenicilliumisolates tested, significantly increased seed germination when compared with the control seeds. Cultural extracts ofP. expensumandP. billiwere highly effective in growth promotion up to 90%. It was also observed thatP. implicatumandP. oxlalicamsignificantly enhanced the root growth in tomato seedling as compare to other species. In case of shoot length,P. verrucosum(3.38),P. granulatum(2.81) andP. implicatum(2.62) were effective. HoweverP. implicatumwas quite promising to increase shoot and root length in tomato seedlings. Where asP. simplicissimiumandP. citrinumwere leas effective on seedling growth. The plant growth promoting ability ofPenicilliumstrains may help in growth permotion in other plants and crops.Penicilliumspp. are already known for producing mycotoxin and enzymes. Plant growth promoting ability ofPenicilliumspp will open new aspects of research and investigations. The role ofPenicil-liumspp. in tomato plant growth requires further exploration.


2020 ◽  
Author(s):  
Marina Soneghett Cotta ◽  
Fernanda Plucani do Amaral ◽  
Leonardo Magalhães Cruz ◽  
Roseli Wassem ◽  
Fábio de Oliveira Pedrosa ◽  
...  

ABSTRACTThe plant growth promoting bacterium (PGPB) Bacillus pumilus TUAT-1 is an indole acetic acid producer that can increase plant growth. Inoculation with this strain has been shown to confer greater plant tolerance to drought and saline conditions. Although the ability of TUAT-1 to enhance plant growth is well documented, little is known about what mechanisms underlie the plant response to this bacterium. Applying genome-wide association study (GWAS), we evaluated the interaction between TUAT-1 and Arabidopsis thaliana, screening 288 plant ecotypes for root architecture traits comparing non-inoculated and inoculated plants. Most of the ecotypes were significantly affected by TUAT-1 inoculation (66.7%) for at least one of the root traits measured. For example, some ecotypes responded positively increasing root growth while others showed reduced growth upon inoculation. A total of 96 ecotypes (33.3%) did not respond significantly to PGPB inoculation. These results are consistent with the widely reported strain-genotype specificity shown in many plant-microbe interactions. The GWAS analysis revealed significant SNPs associated to specific root traits leading to identification of several genes putatively involved in enabling the Bacillus pumilus TUAT-1 and A. thaliana association and contributing to plant growth promotion. Our results show that root architecture features are genetic separable traits associated with plant growth in association with TUAT-1. Our findings validate previous reported genes involved in Bacillus spp.-plant interaction, growth promotion and highlight potential genes involved in plant microbe interaction. We suggest that plant-bacterial interaction and the plant growth promotion are quantitative and multigenic traits. This knowledge expands our understanding of the functional mechanisms driving plant growth promotion by PGPB.


PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11373
Author(s):  
Claudia Clavero-León ◽  
Daniela Ruiz ◽  
Javier Cillero ◽  
Julieta Orlando ◽  
Bernardo González

Copper (Cu) is important for plant growth, but high concentrations can lead to detrimental effects such as primary root length inhibition, vegetative tissue chlorosis, and even plant death. The interaction between plant-soil microbiota and roots can potentially affect metal mobility and availability, and, therefore, overall plant metal concentration. Cupriavidus metallidurans CH34 is a multi metal-resistant bacterial model that alters metal mobility and bioavailability through ion pumping, metal complexation, and reduction processes. The interactions between strain CH34 and plants may affect the growth, metal uptake, and translocation of Arabidopsis thaliana plants that are exposed to or not exposed to Cu. In this study, we looked also at the specific gene expression changes in C. metallidurans when co-cultured with Cu-exposed A. thaliana. We found that A. thaliana’s rosette area, primary and secondary root growth, and dry weight were affected by strain CH34, and that beneficial or detrimental effects depended on Cu concentration. An increase in some plant growth parameters was observed at copper concentrations lower than 50 µM and significant detrimental effects were found at concentrations higher than 50 µM Cu. We also observed up to a 90% increase and 60% decrease in metal accumulation and mobilization in inoculated A. thaliana. In turn, copper-stressed A. thaliana altered C. metallidurans colonization, and cop genes that encoded copper resistance in strain CH34 were induced by the combination of A. thaliana and Cu. These results reveal the complexity of the plant-bacteria-metal triad and will contribute to our understanding of their applications in plant growth promotion, protection, and phytoremediation strategies.


2022 ◽  
Vol 12 ◽  
Author(s):  
Wenbo Fu ◽  
Yanshuo Pan ◽  
Yuhua Shi ◽  
Jieyin Chen ◽  
Daozhi Gong ◽  
...  

In this study, the capacity to tune root morphogenesis by a plant growth-promoting rhizobacterium, Streptomyces lincolnensis L4, was investigated from various aspects including microbial physiology, root development, and root endophytic microbial community. Strain L4 was isolated from the root-associated soil of 7-year plantation of Artemisia annua. Aiming at revealing the promotion mechanism of Streptomyces on root growth and development, this study first evaluated the growth promotion characters of S. lincolnensis L4, followed by investigation in the effect of L4 inoculation on root morphology, endophytic microbiota of root system, and expression of genes involved in root development in Arabidopsis thaliana. Streptomyces lincolnensis L4 is able to hydrolyze organic and inorganic phosphorus, fix nitrogen, and produce IAA, ACC deaminase, and siderophore, which shaped specific structure of endophytic bacterial community with dominant Streptomyces in roots and promoted the development of roots. From the observation of root development characteristics, root length, root diameter, and the number of root hairs were increased by inoculation of strain L4, which were verified by the differential expression of root development-related genes in A. thaliana. Genomic traits of S. lincolnensis L4 which further revealed its capacity for plant growth promotion in which genes involved in phosphorus solubilization, ACC deamination, iron transportation, and IAA production were identified. This root growth-promoting strain has the potential to develop green method for regulating plant development. These findings provide us ecological knowledge of microenvironment around root system and a new approach for regulating root development.


Author(s):  
Bradley R. Dotson ◽  
Vasiliki Verschut ◽  
Klas Flärdh ◽  
Paul G. Becher ◽  
Allan G. Rasmusson

AbstractPlants enhance their growth in the presence of particular soil bacteria due to volatile compounds affecting the homeostasis of plant growth hormones. However, the mechanisms of volatile compound signaling and plant perception has been unclear. This study identifies the bioactive volatile 3-octanone as a plant growth stimulating volatile, constitutively emitted by the soil bacterium Streptomyces coelicolor grown on a rich medium. When 3-octanone is applied to developing Arabidopsis thaliana seedlings, a family-wide induction of the Kelch-repeat F-box genes known as KISS ME DEADLY (KMD) subsequently alters auxin/cytokinin homeostasis to promote the growth of lateral roots and inhibit the primary root. Loss of function of the KMD family or other alterations of auxin/cytokinin homeostasis suppresses the volatile-induced growth response. This reveals a function of KMDs in the pathway of microbial volatile perception and plant growth responses.Significance StatementVolatiles from soil microbes are profound stimulators of plant growth. This work identifies for the first time a plant hormone signaling regulator, the gene family KISS ME DEADLY (KMD), to be an early essential step in plant growth promotion by a soil bacterial volatile, 3-octanone. The KMD-regulated gene network alters the tissue sensitivity balance for the growth hormones auxin and cytokinin, modifying root growth rate and architecture. Previously, the Kelch repeat F-box gene family of KMDs have been shown to be important down-regulators of both positive cytokinin signaling and phenylpropanoid biosynthesis, but upstream cues were unknown. This report places the KMD family regulation of plant growth and defense into its biotic context.


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