Galactinol synthase transcriptional profile in two genotypes of Coffea canephora with contrasting tolerance to drought

Abstract

Increased synthesis of galactinol and raffinose family oligosaccharides (RFOs) has been reported in vegetative tissues in response to a range of abiotic stresses. In this work, we evaluated the transcriptional profile of a Coffea canephora galactinol synthase gene (CcGolS1) in two clones that differed in tolerance to water deficit in order to assess the contribution of this gene to drought tolerance. The expression of CcGolS1 in leaves was differentially regulated by water deficit, depending on the intensity of stress and the genotype. In clone 109A (drought-susceptible), the abundance of CcGolS1 transcripts decreased upon exposure to drought, reaching minimum values during recovery from severe water deficit and stress. In contrast, CcGolS1 gene expression in clone 14 (drought-tolerant) was stimulated by water deficit. Changes in galactinol and RFO content did not correlate with variation in the steady-state transcript level. However, the magnitude of increase in RFO accumulation was higher in the tolerant cultivar, mainly under severe water deficit. The finding that the drought-tolerant coffee clone showed enhanced accumulation of CcGolS1 transcripts and RFOs under water deficit suggests the possibility of using this gene to improve drought tolerance in this important crop.

Varying water deficit stress (WDS) tolerance in grain amaranths involves multifactorial shifts in WDS-related responses

“…The differences observed between WDS tolerant and susceptible amaranths were mostly quantitative and were of importance in roots, where the expression AhGolS1 and AhRafS was significantly higher in WDS-tolerant species, especially under SWDS (Table 4). These results were consistent with findings in leaves of Coffea canephora clones with contrasting tolerance to WDS, where the expression of the CcGolS1 gene differed between drought-tolerant and -sensitive clones, being strongly repressed in the latter (dos Santos et al , 2015). Additionally, a related study in C. arabica reported that, similar to amaranth, the CaGolS1 isoform was highly responsive to WDS (dos Santos et al ., 2011).…”

“…This possibility remains to be determined. Nevertheless, it was in agreement with dos Santos et al (2011, 2015) who argued that the drought-related increase in Gol biosynthesis in coffee was funneled to the generation of larger stress-protective RFOs by unidentified glycosyltransferases.…”

Transcriptome Analysis of Leaves, Flowers and Fruits Perisperm of Coffea arabica L. Reveals the Differential Expression of Genes Involved in Raffinose Biosynthesis

“…RFOs act as signal molecules in response to stress [19–20] and are related to seed desiccation tolerance and germination [21–22]. In coffee plants, RFOs are involved in osmoprotection against abiotic stresses in leaves [23–24], but they can also be possible donors of carbon skeletons during the synthesis of cell wall storage polysaccharides (CWSPs). A microarray-based analysis in coffee endosperm showed that the GolS transcript levels were significantly correlated with the amount of CWSPs [17].…”

Transcriptomic and metabolomic analyses of Lycium ruthenicum and Lycium barbarum fruits during ripening

“…In agreement with this observation are also the results of comparative interspecific individual metabolite analyses, where a number of metabolites associated with abiotic stress topped the list of most highly significantly differentially regulated metabolites between the ripe fruits of the two species (here we focus only on the ripe fruits, as they are more interesting than other studied stages from the human perspective). Plants counteract the deleterious effects of drought by accumulating osmolytes, such as amino acids, amines and some soluble carbohydrates (especially the raffinose family), which have a vital role for the stability of cellular structures under adverse environmental conditions 40,42,43 . Increased level of raffinose in post-colour breaking stages of fruit development in LR was observed recently, and associated with osmoregulation requirements 3 .…”

“…In our study, raffinose was also increased in LR (3.6-fold), as was another raffinose family oligosaccharide, galactinol (11.7-fold). A heightened synthesis of galactinol has been reported in plants in response to a range of abiotic stressors, so it is believed to function as an osmoprotectant in drought-stress tolerance of plants [42][43][44] . Intriguingly, another carbohydrate highly enriched (8.09-fold) in LR, trehalose, is a disaccharide of glucose that functions as an osmoprotectant under abiotic stress in bacteria, fungi, and invertebrates, but it generally does not accumulate in detectable levels in most plants, with the exception of desiccation-tolerant "resurrection plants" 45,46 .…”