Characterization of raffinose metabolism genes uncovers a wild Arachis galactinol synthase conferring tolerance to abiotic stresses

Abstract

Raffinose family oligosaccharides (RFOs) are implicated in plant regulatory mechanisms of abiotic stresses tolerance and, despite their antinutritional proprieties in grain legumes, little information is available about the enzymes involved in RFO metabolism in Fabaceae species. In the present study, the systematic survey of legume proteins belonging to five key enzymes involved in the metabolism of RFOs (galactinol synthase, raffinose synthase, stachyose synthase, alpha-galactosidase, and beta-fructofuranosidase) identified 28 coding-genes in Arachis duranensis and 31 in A. ipaënsis. Their phylogenetic relationships, gene structures, protein domains, and chromosome distribution patterns were also determined. Based on the expression profiling of these genes under water deficit treatments, a galactinol synthase candidate gene (AdGolS3) was identified in A. duranensis. Transgenic Arabidopsis plants overexpressing AdGolS3 exhibited increased levels of raffinose and reduced stress symptoms under drought, osmotic, and salt stresses. Metabolite and expression profiling suggested that AdGolS3 overexpression was associated with fewer metabolic perturbations under drought stress, together with better protection against oxidative damage. Overall, this study enabled the identification of a promising GolS candidate gene for metabolic engineering of sugars to improve abiotic stress tolerance in crops, whilst also contributing to the understanding of RFO metabolism in legume species.

Contrasting Metabolic Fingerprints and Seed Protein Profiles of Cucurbita foetidissima and C. radicans Fruits from Feral Plants Sampled in Central Mexico

“…An interesting outcome was that except for Fru in the pulp, MI in the seeds and peels and Sta in the peels of C. radicans, the levels of almost all NSCs and RFOs analyzed were higher in C. foetidissima. This result suggested speciesspecific differences in carbon partitioning and in the synthesis of RFOs, acting perhaps as abiotic stress-regulating osmolytes and/or seed vigor/seed-desiccation tolerance factors, as reported previously in cucurbits and other plant species [103][104][105][106][107][108][109].…”

Comparative Transcriptomics and Metabolomics Reveal an Intricate Priming Mechanism Involved in PGPR-Mediated Salt Tolerance in Tomato

“…Their mode of action involves the protection of membranes from hydroxyl radicals, as they are found between the head groups of lipids. The formation of galactinol from myo-inositol is catalyzed by galactinol synthase, representing the first enzyme that commits carbon toward RFO formation (Vinson et al, 2020). Transcript levels of this gene were only significantly induced in AXSa06-inoculated plants exposed to 200 mM NaCl, indicating an additional role of galactinols as osmoprotectants and stabilizers of cellular membranes, but also as scavengers of ROS under excess salt (Nishizawa et al, 2008).…”

Importance of inositols and their derivatives in cowpea under root dehydration: An omics perspective

“…The authors suggested that such behavior is associated with less inhibition of plant growth, restricting excessive ROS accumulation and a consequent lipid peroxidation. Vinson et al (2020), in turn, obtained a transgenic Arabidopsis plant overexpressing AdGolS3 (GOLS candidate gene from A . duranensis ).…”

“…The authors suggested that such behavior is associated with less inhibition of plant growth, restricting excessive ROS accumulation and a consequent lipid peroxidation. Vinson et al (2020), in turn, obtained a transgenic Arabidopsis plant overexpressing AdGolS3 (GOLS candidate gene from A. duranensis). The genetically modified organism showed increased levels of raffinose and less stress symptoms under drought, osmotic (PEG 6000, 20%), and salt (NaCl, 150 mM) stress.…”

“…In turn, Gu et al (2018) performed a gene expression analysis of α‐galactosidase (α‐GAL), RS, and GOLS in cucumber leaves under low‐temperature stress. Finally, Vinson et al (2020) performed a systematic (genomics and transcriptomics) study of the five enzymes involved in RFOs metabolism (GOLS, RS, STS, α‐GAL, and β‐fructofuranosidase) in Arachis duranensis and Arachis ipaënsis . So far, our group (Ferreira‐Neto et al, 2019) has developed a unique study exploring genomics and transcriptomics of all components of the two mentioned pathways for a single plant species (soybean).…”