Molecular mechanisms of desiccation tolerance in resurrection plants

Abstract

Resurrection plants are a small but diverse group of land plants characterized by their tolerance to extreme drought or desiccation. They have the unique ability to survive months to years without water, lose most of the free water in their vegetative tissues, fall into anabiosis, and, upon rewatering, quickly regain normal activity. Thus, they are fundamentally different from other drought-surviving plants such as succulents or ephemerals, which cope with drought by maintaining higher steady state water potential or via a short life cycle, respectively. This review describes the unique physiological and molecular adaptations of resurrection plants enabling them to withstand long periods of desiccation. The recent transcriptome analysis of Craterostigma plantagineum and Haberlea rhodopensis under drought, desiccation, and subsequent rehydration revealed common genetic pathways with other desiccation-tolerant species as well as unique genes that might contribute to the outstanding desiccation tolerance of the two resurrection species. While some of the molecular responses appear to be common for both drought stress and desiccation, resurrection plants also possess genes that are highly induced or repressed during desiccation with no apparent sequence homologies to genes of other species. Thus, resurrection plants are potential sources for gene discovery. Further proteome and metabolome analyses of the resurrection plants contributed to a better understanding of molecular mechanisms that are involved in surviving severe water loss. Understanding the cellular mechanisms of desiccation tolerance in this unique group of plants may enable future molecular improvement of drought tolerance in crop plants.

The evolution of desiccation tolerance in angiosperm plants: a rare yet common phenomenon

“…Of particular note are the transcription factor and signalling associated gene transcripts that respond to desiccation and rehydration. The genes these transcripts represent are targeted as the underlying genetic components that control the massive reprogramming of cellular activity that determines desiccation tolerance (Gechev et al 2012). The larger transcriptome studies also support earlier more targeted gene expression profiling studies with the resurrection monocot Xerophyta humilis that offered the first transcriptomic evidence for the hypothesis that vegetative desiccation tolerance in the resurrection angiosperms derived from the genetic program that is operational in the seed (Illing et al 2005).…”

“…quenching by carotenoids and the antioxidant action of glutathione-ascorbate cycle enzymes and catalase (Gaff et al 2009;Oliver et al 2011b;Gechev et al 2012;Dinakar et al 2012). Rises in the contents of tocopherol, putrescine and agmatine, lipid anti-oxidants, may safeguard membrane integrity during drying of Sporobolus stapfianus (Oliver et al 2011a).…”

“…Large comprehensive transcriptome profiling studies of drying and rehydration tissues have been reported for two dicot resurrection plants, Craterostigma plantagineum (Rodriguez et al 2010) and Haberlea rhodopensis (Gechev et al 2013), in an attempt to build a more comprehensive assessment of the cellular protection aspects of the molecular mechanisms of tolerance in these plants (reviewed by Gechev et al 2012). These studies, in general, support the proteomic and metabolomic aspects of the desiccation responses as discussed earlier but they also point to novel aspects that offer new insights into the cellular protection mechanisms and the processes that are important for successful recovery upon rehydration.…”

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

“…Desiccation-sensitive and resurrection plants may share similar mechanisms of drought perception and dehydration responses such as the induction of late embryogenesis abundant (LEA) and heat shock (HS) genes, or the adjustment of carbohydrate metabolism; however, the final physiological result varies between species, and tolerance to desiccation is only observed in the resurrection plants [11]. This difference implies the existence of additional, unique protective mechanisms in the resurrection plants, a notion corroborated by the identification of the unusual eight-carbon sugar octulose, the CDT1 gene in Craterostigma plantagineum, and the phenolic antioxidant 3,4,5-tri-O-galloylquinic acid in Myrothamnus flabellifolia [12][13][14][15].…”

Potenciais Hídricos E Teores De Água Na Germinação De Sementes E Crescimento Inicial De Milheto

“…(Penfield et al, 2001); sementes de feijão (Phaseolus vulgaris) com teores de água de 9, 11 e 13% apresentaram redução crescente da germinação à medida que as disponibilidades hídricas foram sendo reduzidas a partir de -0,04 MPa com PEG (Forti et al, 2009); em sementes de Urochloa ruziziensis, a extensão dos danos provocados na germinação e no crescimento de plântulas deve-se à severidade do estresse hídrico causado por PEG e ao teor de água de 9,5% nas sementes (Masetto et al, 2013). em sementes mutantes de Arabidopsis thaliana sem os polissacarídeos depositados no tegumento responsáveis pela formação de uma mucilagem (que promove a umidade controlando a embebição de água), ocorre redução da germinação em meio osmótico com PEG (Penfield et al, 2001); sementes de feijão (Phaseolus vulgaris) com teores de água de 9, 11 e 13% apresentaram redução crescente da germinação à medida que as disponibilidades hídricas foram sendo reduzidas a partir de -0,04 MPa com PEG (Forti et al, 2009); em sementes de Urochloa ruziziensis, a extensão dos danos provocados na germinação e no crescimento de plântulas deve-se à severidade do estresse hídrico causado por PEG e ao teor de água de 9,5% nas sementes (Masetto et al, 2013 Gechev et al (2012), as plantas se adaptam à seca por meio de numerosos mecanismos fisiológicos e morfológicos, sendo que alguns são imediatos ao estresse, como o fechamento estomático governado principalmente por ácido abcísico (ABA). Entretanto, mudanças na arquitetura radicular, como o crescimento de raízes em resposta ao estresse hídrico, estão associadas à redução do crescimento da parte aérea.…”