Strigolactones (SLs) are considered to be a novel class of phytohormone involved in plant defense responses. Currently, their relationships with other plant hormones, such as abscisic acid (ABA), ...during responses to salinity stress are largely unknown.
In this study, the relationship between SL and ABA during the induction of H
O
- mediated tolerance to salt stress were studied in arbuscular mycorrhizal (AM) Sesbania cannabina seedlings. The SL levels increased after ABA treatments and decreased when ABA biosynthesis was inhibited in AM plants. Additionally, the expression levels of SL-biosynthesis genes in AM plants increased following treatments with exogenous ABA and H
O
. Furthermore, ABA-induced SL production was blocked by a pre-treatment with dimethylthiourea, which scavenges H
O
. In contrast, ABA production was unaffected by dimethylthiourea. Abscisic acid induced only partial and transient increases in the salt tolerance of TIS108 (a SL synthesis inhibitor) treated AM plants, whereas SL induced considerable and prolonged increases in salt tolerance after a pre-treatment with tungstate.
These results strongly suggest that ABA is regulating the induction of salt tolerance by SL in AM S. cannabina seedlings.
Arbuscular mycorrhiza can improve the salt-tolerance of host plant. A systematic study of mycorrhizal plant responses to salt stress may provide insights into the acquired salt tolerance. Here, the ...transcriptional profiles of mycorrhizal Sesbania cannabina shoot and root under saline stress were obtained by RNA-Seq. Using weighted gene coexpression network analysis and pairwise comparisons, we identified coexpressed modules, networks and hub genes in mycorrhizal S. cannabina in response to salt stress. In total, 10,371 DEGs were parsed into five coexpression gene modules. One module was positively correlated with both salt treatment and arbuscular mycorrhizal (AM) inoculation, and associated with photosynthesis and ROS scavenging in both enzymatic and nonenzymatic pathways. The hub genes in the module were mostly transcription factors including WRKY, MYB, ETHYLENE RESPONSE FACTOR, and TCP members involved in the circadian clock and might represent central regulatory components of acquired salinity tolerance in AM S. cannabina. The expression patterns of 12 genes involved in photosynthesis, oxidation-reduction processes, and several transcription factors revealed by qRT-PCR confirmed the RNA-Seq data. This large-scale assessment of Sesbania genomic resources will help in exploring the molecular mechanisms underlying plant-AM fungi interaction in salt stress responses.
Uranium phytoextraction is a promising technology, however, facing difficult that limited plant biomass due to nutrient deficiency in the contaminated sites. The aim of this study is to evaluate the ...potential of a symbiotic associations of a legume Sesbania rostrata, rhizobia and arbuscular mycorrhiza fungi (AMF) for reclamation of uranium contaminated soils. Results showed AMF and rhizobia had a mutual beneficial relations in the triple symbiosis, which significantly increased plant biomass and uranium accumulation in S. rostrata plant. The highest uranium removal rates was observed in plant-AMF-rhizobia treated soils, in which 50.5–73.2% had been extracted, whereas 7.2–23.3% had been extracted in plant-treated soil. Also, the S. rostrata phytochelatin synthase (PCS) genes expression were increased in AMF and rhizobia plants compared with the plants. Meantime, content of malic acid, succinic acid and citric acid were elevated in S. rostrata root exudates of AMF and rhizobia inoculated plants. The facts suggest that the mutual interactions in the triple symbiosis help to improve phytoremediation efficiency of uranium by S. rostrata.
•AMF and rhizobium had a mutual beneficial relations.•The inoculation of AMF/rhizobium enhanced PCS genes expression.•AMF/rhizobium improve phytoremediation efficiency of uranium by S. rostrata.
Aureobasidium spp. can use a wide range of substrates and are widely distributed in different environments, suggesting that they can sense and response to various extracellular signals and be adapted ...to different environments. It is true that their pullulan, lipid and liamocin biosynthesis and cell growth are regulated by the cAMP-PKA signaling pathway; Polymalate (PMA) and pullulan biosynthesis is controlled by the Ca2+ and TORC1 signaling pathways; the HOG1 signaling pathway determines high osmotic tolerance and high pullulan and liamocin biosynthesis; the Snf1/Mig1 pathway controls glucose repression on pullulan and liamocin biosynthesis; DHN-melanin biosynthesis and stress resistance are regulated by the CWI signaling pathway and TORC1 signaling pathway. In addition, the HSF1 pathway may control cell growth of some novel strains of A. melanogenum at 37 °C. However, the detailed molecular mechanisms of high temperature growth and thermotolerance of some novel strains of A. melanogenum and glucose derepression in A. melanogenum TN3–1 are still unclear.
•The progress in the roles of different signaling pathways in Aureobasidium spp. was reviewed.•Different signaling pathways can play roles in the secondary metabolisms and stress responses.•The mechanisms of thermotolerance of A. melanogenum are still unclear.•The mechanisms of natural glucose derepression were needed to be further investigated.
L-piperazic acid (L-Piz) is one of components in many bioactive compounds synthesized by Streptomyces spp. Therefore, it is very important to develop a sustainable and eco-friendly bioprocess to ...produce L-Piz from renewable glucose. In this study, it was found that the engineered Aureobasidium melanogenum DFAK-ArgB6 strain overexpressing the ArgB gene encoding N-acetylglutamate kinase could produce 3.0 g/L L-Piz from glucose during the fed-batch fermentation. The yield was 55.6 mg L-Piz/g of glucose and the productivity was 24.8 mg/L/h. This was the highest amount of L-Piz produced by microorganisms so far. Finally, the partially purified L-Piz had purity of 86.4%.
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•L-piperazic acid (L-Piz) is one of components in many bioactive compounds.•The DFAK-ArgB6 strain could produce the highest amount of L-Piz (3.0 g/L).•The partially purified L-Piz was obtained.
Sesbania cannabina, a multipurpose leguminous crop, is highly resistant to waterlogging stress. However, the scant genomic resources in the genus Sesbania have greatly hindered further exploration of ...the mechanisms underlying its waterlogging tolerance. Here, the genetic basis of flooding tolerance in S. cannabina was examined by transcriptome-wide gene expression changes using RNA-Seq in seedlings exposed to short-term (3 h) and long-term (27 h) waterlogging. After de- novo assembly, 213990 unigenes were identified, of which 145162 (79.6%) were annotated. Gene Ontology and pathway enrichment analyses revealed that the glycolysis and fermentation pathways were stimulated to produce ATP under hypoxic stress conditions. Energy-consuming biosynthetic processes were dramatically repressed by short and long term waterlogging, while amino acid metabolism was greatly induced to maintain ATP levels. The expression pattern of 10 unigenes involved in phenylpropanoid biosynthesis, glycolysis, and amino acid metabolism revealed by qRT-PCR confirmed the RNA-Seq data. The present study is a large-scale assessment of genomic resources of Sesbania and provides guidelines for probing the molecular mechanisms underlying S. cannabina waterlogging tolerance.
Soil salinity adversely affects plant growth and has become a major limiting factor for agricultural development worldwide. There is a continuing demand for sustainable technology innovation in ...saline agriculture. Among various bio-techniques being used to reduce the salinity hazard, symbiotic microorganisms such as rhizobia and arbuscular mycorrhizal (AM) fungi have proved to be efficient. These symbiotic associations each deploy an array of well-tuned mechanisms to provide salinity tolerance for the plant. In this review, we first comprehensively cover major research advances in symbiont-induced salinity tolerance in plants. Second, we describe the common signaling process used by legumes to control symbiosis establishment with rhizobia and AM fungi. Multi-omics technologies have enabled us to identify and characterize more genes involved in symbiosis, and eventually, map out the key signaling pathways. These developments have laid the foundation for technological innovations that use symbiotic microorganisms to improve crop salt tolerance on a larger scale. Thus, with the aim of better utilizing symbiotic microorganisms in saline agriculture, we propose the possibility of developing non-legume 'holobionts' by taking advantage of newly developed genome editing technology. This will open a new avenue for capitalizing on symbiotic microorganisms to enhance plant saline tolerance for increased sustainability and yields in saline agriculture.
Legumes can host rhizobia and mycorrhizal fungi, and this triple symbiosis might be exploited to improve saline soil fertility. Therefore, a greater understanding of the interaction of rhizobia and ...arbuscular mycorrhizal fungus during legume growth in saline soil is required. We investigated the efficiency of salt tolerance conferred by rhizobia in mycorrhizal
Sesbania cannabina
. Greenhouse experiments were conducted in which
S. cannabina
plants inoculated with
Glomus mosseae
BGC NM03D (GM), and two rhizobia strains
Agrobacterium pusense
YIC4105 (4105) and
Neorhizobium huautlense
YIC4083 (4083), were exposed to 100 and 200 mM NaCl. Under 200 mM NaCl stress, plants inoculated with 4105, rather than 4083, showed significant increases in shoot and root dry mass compared with non-inoculated plants. Simultaneously, a significant increase over GM-inoculated plants in mycorrhizal colonization and dependency was recorded for 4105 + GM-inoculated plants compared with 4083 + GM-inoculated plants. In addition, under NaCl stress, significant increases in the number and mass of nodules, nitrogenase activity, and leghemoglobin content of nodules occurred in 4105 + GM-inoculated plants compared with 4083 + GM-inoculated plants. Furthermore, the activities of antioxidant enzymes in rhizobia-inoculated plants were significantly higher in the GM + 4105 group than the 4083 + GM group. The malondialdehyde content of plants from the 4105 + GM group was significantly lower than in the 4083 + GM group. Thus, the results revealed a synergistic relationship among the 4105 and GM in alleviating salt stress in
S. cannabina
. Salt-tolerant rhizobia might improve the salinity tolerance of
S. cannabina
by enhancing the antioxidant system.
Aureobasidium melanogenum HN6.2 is a high siderophore-producing yeast-like fungal strain. After blocking siderophore biosynthesis and attenuating the expression of the ornithine carbamoyltransferase ...gene (the OTC gene), the obtained D-LCFAO-cre strain produced 2.1 ± 0.02 mg of intracellular L-ornithine per mg of the protein. The overexpression of the L-ornithine decarboxylase gene (the SPE1-S gene) from Saccharomyces cerevisiae in the mutant D-LCFAO-cre could make the transformant E-SPE1-S synthesize 3.6 ± 0.1 of intracellular ornithine per mg of protein and produce 10.5 g/L of putrescine. The further overexpression of the ArgB/C gene encoding bifunctional acetylglutamate kinase/N-acetyl-gamma-glutamyl-phosphate reductase in the transformant E-SPE1-S caused the transformant E-SPE1-S-ArgB/C to accumulate L-ornithine (4.2 mg/mg protein) and to produce 21.3 g/L of putrescine. During fed-batch fermentation, the transformant E-SPE1-S-ArgB/C could produce 33.4 g/L of putrescine, the yield was 0.96 g/g of glucose, and the productivity was 0.28 g/L/h. The putrescine titer was much higher than that produced by most engineered strains obtained thus far.
•The transformant E-SPE1-S produced 10.5 g/L putrescine.•The transformant E-SPE1-S-ArgB/C produced 21.3 g/L of putrescine.•During fed-batch fermentation, the transformant E-SPE1-S-ArgB/C produced 33.4 g/L of putrescine.•The putrescine titer was the highest.•The transformant E-SPE1-S-ArgB/C has high potential applications.
The arbuscular mycorrhizal symbiosis can alleviate salt stress in plants by altering strigolactone levels in the host plant. The aim of this study was to investigate the mechanism by which ...strigolactones enhance salt stress tolerance in arbuscular mycorrhizal
Sesbania cannabina
seedlings. Strigolactone levels, as determined by means of germination bioassay, gradually increased with treatment time of NaCl applied. Inhibition of NADPH oxidase activity and chemical scavenging of H
2
O
2
significantly reduced strigolactone-induced salt tolerance and decreased strigolactone levels. The H
2
O
2
-induced strigolactone accumulation was accompanied by increased tolerance to salt stress. These results strongly indicated that elevated H
2
O
2
concentration resulting from enhanced NADPH oxidase activity regulated strigolactone-induced salt stress tolerance in arbuscular mycorrhizal
S. cannabina
seedlings.
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