Prunus Hexokinase 3 genes alter primary C-metabolism and promote drought and salt stress tolerance in Arabidopsis transgenic plants

Abstract

Hexokinases (HXKs) and fructokinases (FRKs) are the only two families of enzymes in plants that have been identified as able to phosphorylate Glucose (Glc) and Fructose (Fru). Glc can only be phosphorylated in plants by HXKs, while Fru can be phosphorylated by either HXKs or FRKs. The various subcellular localizations of HXKs in plants indicate that they are involved in diverse functions, including anther dehiscence and pollen germination, stomatal closure in response to sugar levels, stomatal aperture and reducing transpiration. Its association with modulating programmed cell death, and responses to oxidative stress and pathogen infection (abiotic and biotic stresses) also have been reported. To extend our understanding about the function of HXK-like genes in the response of Prunus rootstocks to abiotic stress, we performed a detailed bioinformatic and functional analysis of hexokinase 3-like genes (HXK3s) from two Prunus rootstock genotypes, ‘M.2624’ (Prunus cerasifera Ehrh × P. munsoniana W.Wight & Hedrick) and ‘M.F12/1’ (P. avium L.), which are tolerant and sensitive to hypoxia stress, respectively. A previous large-scale transcriptome sequencing of roots of these rootstocks, showed that this HXK3-like gene that was highly induced in the tolerant genotype under hypoxia conditions. In silico analysis of gene promoters from M.2624 and M.F12/1 genotypes revealed regulatory elements that could explain differential transcriptional profiles of HXK3 genes. Subcellular localization was determinates by both bioinformatic prediction and expression of their protein fused to the green fluorescent protein (GFP) in protoplasts and transgenic plants of Arabidopsis. Both approaches showed that they are expressed in plastids. Metabolomics analysis of Arabidopsis plants ectopically expressing Prunus HXK3 genes revealed that content of several metabolites including phosphorylated sugars (G6P), starch and some metabolites associated with the TCA cycle were affected. These transgenic Arabidopsis plants showed improved tolerance to salt and drought stress under growth chamber conditions. Our results suggest that Prunus HXK3 is a potential candidate for enhancing tolerance to salt and drought stresses in stone fruit trees and other plants.

Molecular cues of sugar signaling in plants

“…Sucrose down‐regulates WRK4 (triggered by CK), a putative kinase member of the SNF1 KINASE subfamily. CK and glucose trigger the HXK1 pathway for root elongation in Arabidopsis seedlings (Pérez‐Díaz et al, 2021). During glucose application, T6P inhibited ABA synthesis and signaling and acted antagonistically to SnRK1 in Arabidopsis seedlings.…”

“…regulates WRK4 (triggered by CK), a putative kinase member of the SNF1 KINASE subfamily. CK and glucose trigger the HXK1 pathway for root elongation in Arabidopsis seedlings(Pérez-Díaz et al, 2021).During glucose application, T6P inhibited ABA synthesis and signaling and acted antagonistically to SnRK1 in Arabidopsis seedlings. CK antagonizes the ABA signaling by impeding SnRK2 activity through type-B ARRs and, therefore, promotes the seedling establishment(Wang et al, 2021).…”

Overexpression of a Voltage-Dependent Anion-Selective Channel (VDAC) Protein-Encoding Gene, MsVDAC, from Medicago sativa Confers Cold and Drought Tolerance to Transgenic Tobacco

“…Hexokinase, a functional regulator of VDAC, has been proven to play a role in pathogen induction and H 2 O 2 -induced cell death in plants [35]. Metabolomics analysis of A. thaliana ectopically expressing the Hxk3 gene showed that phosphorylated sugar (G6P), starch and some metabolites related to the tricarboxylic acid (TCA) cycle are affected [36]. LTP1 plays a role in fatty acid binding and phospholipid and lipid transfer between membranes in vitro [37] and can be strongly induced in Lotus japonicus in response to drought stress [38] and in wheat under cold stress [39].…”

Combined metabolomic and transcriptomic analysis reveals key components of OsCIPK17 overexpression improves drought tolerance in rice

“…Apparently, the TCA cycle-associated proteins are upregulated under drought stress ( Wang et al., 2019 ). Previous metabolomic analyses have revealed ectopic expression of the Prunus HXK3 gene in Arabidopsis increased the contents of phosphorylated sugars, starch, and some TCA cycle-related metabolites to enhance drought tolerance ( Pérez-Díaz et al., 2021 ).…”