Molecular mechanisms of desiccation tolerance in the resurrection glacial relic Haberlea rhodopensis

A systems biology perspective on the role of WRKY transcription factors in drought responses in plants

“…Reports from resurrection plants using parallel transcriptomic and metabolomic profiling have reported on wRKY TFs as regulating lysine biosynthesis (Urbanczyk-wochniak et al 2003), reprogramming normal growth to promote energy saving and promoting stress protective programs during water stress (Gechev et al 2013). In their study, Urbanczykwochniak et al (2003) found that the nutritionally important metabolites such as ascorbate, tocopherol and lysine were closely related to the expression of various transcription factors: ascorbate was negatively correlated with a homologue of the clock gene CONSTANS and lysine was positively regulated by the transcription factor wRKY6.…”

“…The BhGolS1 promoter contains four w boxes and chromatin immunoprecipitation showed that it is bound in vivo by the early dehydration and ABA-inducible BhwRKY1 transcription factor (wang et al 2009). Gechev et al (2013) produced a model where they explained that initial perception of the signaling events during drought is received by transcription factors including MADS box, NAC and wRKY proteins. This leads to production of eLIPs, LeAs, HSPs, PR proteins, regulation of ROS-scavenging proteins/metabolites, down-regulation of photosynthetic genes, accumulation of sucrose, and synthesis of GABA.…”

Orthodox Seeds and Resurrection Plants: Two of a Kind?

“…An analysis of gene families that expanded and contracted in X. viscosa in relation to 15 other plant genomes, including O. thomaeum, indicated a small overlap in the gene families that expanded and contracted in only these two resurrection species (Costa et al, 2017). A large fraction of the contigs assembled from hydrated, dehydrated, desiccated, and rehydrated samples of the resurrection species Sporobolus stapfianus (Yobi et al, 2017), Craterostigma plantagineum (Giarola and Bartels, 2015), and Haberlea rhodopensis (Gechev et al, 2013) predict the presence of protein sequences that bear little or no similarity to proteins in public databanks. Orphan or taxonomically restricted genes are genes without known homologs that either evolved de novo from noncoding sequences or were derived from older coding material (Arendsee et al, 2014).…”

“…Resurrection plants also experience a metabolic switch during dehydration. When water content drops below ;55% RWC, stomata close, carbon gain from photosynthesis ceases, and metabolism shifts from normal growth to cell defense and the accumulation of protective molecules, such as Suc, raffinose family oligosaccharides, and amino acids (Gechev et al, 2013;Farrant et al, 2015;Mladenov et al, 2015;Yobi et al, 2017). For instance, H. rhodopensis leaves start to accumulate Suc at ;60% RWC during desiccation in parallel with the significant consumption of glycolytic intermediates (Mladenov et al, 2015).…”

“…Seeds and resurrection plants use a complex array of inherent antioxidant molecules to protect themselves from abiotic stress, such as superoxide dismutases, catalases, glutathione and ascorbate peroxidases, flavonoids, and tocopherols (Illing et al, 2005;Djilianov et al, 2011;Dinakar and Bartels, 2012;Gechev et al, 2013;Sano et al, 2016;Farrant et al, 2017). In angiosperm resurrection plants, genes encoding antioxidant enzymes are either constitutively expressed or induced by drought (;50% RWC), particularly desiccation (Dinakar and Bartels, 2012;Gechev et al, 2013;Farrant et al, 2015). In the angiosperm resurrection species Ramonda nathaliae (an HDT), a time-course analysis of different antioxidant enzyme activities revealed the sequential involvement of these enzymes in dehydration and subsequent rehydration (Jovanovic et al, 2011).…”