Jill Farrant
University of Cape Town, Molecular and Cell Biology, Faculty Member
Resurrection plants have an extraordinary ability to survive extreme water loss but still revive full metabolic activity when rehydrated. These plants are useful models to understand the complex biology of vegetative desiccation... more
Resurrection plants have an extraordinary ability to survive extreme water loss but still revive full metabolic activity when rehydrated. These plants are useful models to understand the complex biology of vegetative desiccation tolerance. Despite extensive studies of resurrection plants, many details underlying the mechanisms of desiccation tolerance remain unexplored. To summarize the progress in resurrection plant research and identify unexplored questions, we conducted a systematic review of 15 model angiosperm resurrection plants. This systematic review provides an overview of publication trends on resurrection plants, the geographical distribution of species and studies, and the methodology used. Using the Preferred Reporting Items for Systematic reviews and Meta–Analyses protocol we surveyed all publications on resurrection plants from 2000 and 2020. This yielded 185 empirical articles that matched our selection criteria. The most investigated plants were Craterostigma planta...
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Plant water-deficit stress is considered to be one of the greatest threats to world agriculture. In an effort to identify a better performing crop variety of Eragrostis tef under this stress, the responses of two varieties, white (W) and... more
Plant water-deficit stress is considered to be one of the greatest threats to world agriculture. In an effort to identify a better performing crop variety of Eragrostis tef under this stress, the responses of two varieties, white (W) and brown (B) seeded, were compared with those of the resurrection grass Eragrostis nindensis during a dehydration/rehydration cycle. After 6 days of dehydration, relative water content (RWC) dropped to 33%, 43% and 39% in En, Et(B) and Et(W) plants, respectively. This water loss was accompanied by a decline in transpiration and increased electrolyte leakage in the Et varieties. Et(W) did not recover from this level of drying when watered. Et(B) on the other hand recovered fully from 43% RWC, but lost viability after 9 days dehydration, RWC < 30%. En showed full metabolic recovery from drying to 10% RWC. Loss of viability in the Et varieties was accompanied by an increase in electrolyte leakage and irreversible decline in photosynthesis and transpira...
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SummaryVegetative desiccation tolerance, the ability to survive loss of over 90% of cellular water, is an extremely rare trait in Angiosperms. Xerophyta schlechteri survives such extreme water deficit by entering prolonged quiescence and... more
SummaryVegetative desiccation tolerance, the ability to survive loss of over 90% of cellular water, is an extremely rare trait in Angiosperms. Xerophyta schlechteri survives such extreme water deficit by entering prolonged quiescence and suppressing drought-induced senescence in most of the leaf area, except the apical tip. Information on the molecular regulation of senescence in such plants is scarce and this is the first study to investigate such regulation in senescing and non-senescing tissues of the same leaf.Genome-wide RNA sequencing enabled comparison of senescent and non-senescent tissues during desiccation and early rehydration, establishment of the water content range in which senescence is initiated and identification of molecular mechanisms employed to bring about cellular death.Senescence-associated genes (XsSAG) specific to this species were identified and two potential regulatory sites were enriched in regions upstream to these XsSAGs, allowing us to create a model o...
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ABSTRACTResilience to abiotic stress is associated with a suite of functional traits related to defense and longevity. Stress tolerant plants are generally slow growing with extended leave lifespans and reduced allocation to reproduction.... more
ABSTRACTResilience to abiotic stress is associated with a suite of functional traits related to defense and longevity. Stress tolerant plants are generally slow growing with extended leave lifespans and reduced allocation to reproduction. Resurrection plants are ideal systems to test for trade-offs associated with stress tolerance due to their extreme resiliency. While, growth defense trade-offs are well-characterized, few studies have tested for natural variation associated with tolerating the harshest environments. Here, we surveyed a suite of functional traits related to stress tolerance, leaf economics, and reproductive allocation in natural populations of the South African resurrection plant Myrothamnus flabellifolia. We selected three distinct field sites in South Africa ranging from mesic to xeric. Despite considerable environmental variation across the study area, M. flabellifolia plants were extremely and similarly stress tolerant at all sites. However, we detected notable ...
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This article comments on:Candotto Carniel FC, Fernandez-Marín B, Arc E, Craighero T, Laza MJ, Incerti G, Tretiach M, Kranner I. 2021. How dry is dry? Molecular mobility in relation to thallus water content in a lichen. Journal of... more
This article comments on:Candotto Carniel FC, Fernandez-Marín B, Arc E, Craighero T, Laza MJ, Incerti G, Tretiach M, Kranner I. 2021. How dry is dry? Molecular mobility in relation to thallus water content in a lichen. Journal of Experimental Botany 72, 1576–1588
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The 90-kDa family of heat shock proteins are major molecular chaperones found in bacteria, mammals, yeast and plants with high degree of conservation. The cytosolic Hsp90 and the endoplasmic reticulum-located Grp94 (94-kDa glucose... more
The 90-kDa family of heat shock proteins are major molecular chaperones found in bacteria, mammals, yeast and plants with high degree of conservation. The cytosolic Hsp90 and the endoplasmic reticulum-located Grp94 (94-kDa glucose regulated protein) are the best-characterised representatives. Hsp90 appears to have an important role in the folding and activation of proteins involved in signal transduction and control of the cell cycle, whereas Grp94 has been implicated in the correct folding and assembly of proteins passing through the ER. Until recently the mechanism of action of this important group of proteins was one of the least well understood of the molecular chaperones, but significant progress has been made in understanding its biochemistry. Dissection of the functional domains of the protein has revealed the mechanism of action as well as the importance of conformational transitions for its activity. This review seeks to provide an overview of current knowledge of the struc...
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During desiccation, homoiochlorophyllous resurrection plants retain most of their photosynthetic apparatus, allowing them to resume photosynthetic activity quickly upon water availability. These plants rely on various mechanisms to... more
During desiccation, homoiochlorophyllous resurrection plants retain most of their photosynthetic apparatus, allowing them to resume photosynthetic activity quickly upon water availability. These plants rely on various mechanisms to prevent formation of reactive oxygen species and/or protect their tissues from the damage they inflict. In this work, we addressed the issue of how homoiochlorophyllous resurrection plants deal with the problem of excessive excitation/electron pressures during dehydration using Craterostigma pumilum as a model plant. To investigate the alterations in the supramolecular organization of photosynthetic protein complexes, we examined cryo-immobilized, freeze-fractured leaf tissues using (cryo)-scanning electron microscopy. These examinations revealed rearrangements of photosystem II (PSII) complexes, including a lowered density during moderate dehydration, consistent with a lower level of PSII proteins, as shown by biochemical analyses. The latter also showed...
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Xerophyta humilis (Bak.) Dur. and Schinz is a poikilochlorophyllous resurrection plant in that it is tolerant of considerable water loss (V/FM] using chlorophyll fluorescence) appear to be stabily present in the dried leaves. However, for... more
Xerophyta humilis (Bak.) Dur. and Schinz is a poikilochlorophyllous resurrection plant in that it is tolerant of considerable water loss (V/FM] using chlorophyll fluorescence) appear to be stabily present in the dried leaves. However, for total recovery of FV/FM new genomic transcription is necessary.
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Research Interests: Plant Biology, Desiccation Tolerance, South Africa, Glucose, Experimental Botany, and 13 moreCell Fractionation, Water Stress, Desiccation, Proline, Fructose, Oxford university, Cell Wall, Subcellular Fractions, Epidermal Stem Cells, PLANT PROTEINS, Eragrostis, Water Permeability, and cross sectional area
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The ability of tissues to survive desiccation is common in seeds but rare in vegetative tissues. In this study the ultrastructure of hydrated and dehydrated tissues were examined at different stages of the life cycle of the resurrection... more
The ability of tissues to survive desiccation is common in seeds but rare in vegetative tissues. In this study the ultrastructure of hydrated and dehydrated tissues were examined at different stages of the life cycle of the resurrection grass, Eragrostis nindensis Ficalho & Hiern. Conventional fixation techniques are unsuitable for dry tissues as rehydration occurs during fixation in aqueous fixatives. Thus a cryofixation and freeze-substitution method was developed. As a result of the improved fixation methods, it was possible to identify the stage and nature of the damage in the desiccation-sensitive tissues. E. nindensis has desiccation-tolerant orthodox seeds, but the young seedlings are not tolerant to extreme water loss. However, like the seeds, most of the leaves of the adult plant are tolerant to desiccation (only the oldest outermost leaf on a tiller are not). Desiccation-induced damage in these outer leaves was observed in the later stage of dehydration, dominated by the a...
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The predominant (>90%) low-molecular-mass polyphenol was isolated from the leaves of the resurrection plant Myrothamnus flabellifolius and identified to be 3,4,5 tri-O-galloylquinic acid using 1H and 13C one- and two-dimensional NMR... more
The predominant (>90%) low-molecular-mass polyphenol was isolated from the leaves of the resurrection plant Myrothamnus flabellifolius and identified to be 3,4,5 tri-O-galloylquinic acid using 1H and 13C one- and two-dimensional NMR spectroscopy. The structure was confirmed by mass spectrometric analysis. This compound was present at high concentrations, 44% (by weight) in hydrated leaves and 74% (by weight) in dehydrated leaves. Electron microscopy of leaf material fixed with glutaraldehyde and caffeine demonstrated that the polyphenols were localized in large vacuoles in both hydrated and dehydrated leaves. 3,4,5 Tri-O-galloylquinic acid was shown to stabilize an artificial membrane system, liposomes, against desiccation if the polyphenol concentration was between 1 and 2 μg/μg phospholipid. The phase transition of these liposomes observed at 46 °C was markedly diminished by the presence of 3,4,5 tri-O-galloylquinic acid, suggesting that the presence of the polyphenol maintaine...
Research Interests: Chemistry, Free Radicals, Magnetic Resonance Spectroscopy, Flavonoids, Medicine, and 15 moreFree Radical, Biological Sciences, Polyphenols, Liposomes, Desiccation, Phase transition, Biochemical, Gallic acid, CHEMICAL SCIENCES, Phenols, Angiosperms, Linoleic Acid, Molecular Structure, Plant Leaves, and Medical and Health Sciences
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Vegetative desiccation tolerance, or the ability to survive the loss of ~95% relative water content (RWC), is rare in angiosperms, with these being commonly called resurrection plants. It is a complex multigenic and multi-factorial trait,... more
Vegetative desiccation tolerance, or the ability to survive the loss of ~95% relative water content (RWC), is rare in angiosperms, with these being commonly called resurrection plants. It is a complex multigenic and multi-factorial trait, with its understanding requiring a comprehensive systems biology approach. The aim of the current study was to conduct a label-free proteomic analysis of leaves of the resurrection plant Xerophyta schlechteri in response to desiccation. A targeted metabolomics approach was validated and correlated to the proteomics, contributing the missing link in studies on this species. Three physiological stages were identified: an early response to drying, during which the leaf tissues declined from full turgor to a RWC of ~70–80%, a mid-response in which the RWC declined to 40% and a late response where the tissues declined to 10% RWC. We identified 517 distinct proteins that were differentially expressed, of which 253 proteins were upregulated and 264 were d...
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Land salinization is a major constraint for the practice of agriculture in the world. Considering the extent of this phenomenon, the rehabilitation of ecosystems degraded by salinization has become a priority to guarantee food security in... more
Land salinization is a major constraint for the practice of agriculture in the world. Considering the extent of this phenomenon, the rehabilitation of ecosystems degraded by salinization has become a priority to guarantee food security in semi-arid environments. The mechanical and chemical approaches for rehabilitating salt-affected soils being expensive, an alternative approach is to develop and utilize biological systems utilizing salt-tolerant plant species. Casuarina species are naturally halotolerant, but this tolerance has been shown to be improved when they are inoculated with arbuscular mycorrhizal fungi (AMF) and/or nitrogen-fixing bacteria (Frankia). Furthermore, Casuarina plantations have been proposed to promote the development of plant diversity. Thus, the aim of the current study was to evaluate the impact of a plantation comprising the species Casuarina inoculated with AMF and Frankia on the diversity of the sub-canopy and adjacent vegetation. Work was conducted on a ...
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Selected nutritional and physical properties of the two commonly cultivated Zambian market classes of Bambara groundnut (red and brown) were investigated to establish their end-user traits. Nutritional (essential amino acids, proximate... more
Selected nutritional and physical properties of the two commonly cultivated Zambian market classes of Bambara groundnut (red and brown) were investigated to establish their end-user traits. Nutritional (essential amino acids, proximate and mineral compositions) and physical (hydration capacity, hydration index, swelling capacity, swelling index and 100 seed mass) properties were investigated using established standard methods. All the essential amino acids were present in both the red and brown Bambara groundnuts. The highest amount was recorded for leucine (9.7 g/100g protein) in the brown Bambara groundnut and least for methionine (1.2 g/100g protein) in the red market class. All the essential amino acids except methionine in the brown Bambara groundnut market class were above the recommended WHO/FAO provisional requirements for children (2 – 5 years) and adults. The crude protein values ranged from 14.62-18.55 g/100g, total ash (4.21 – 4.29 g/100g), crude fibre (2.79 – 5.33 g/100...
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The leaves and twigs of the desiccation-tolerant medicinal shrub Myrothamnus flabellifolia are harvested for use in traditional and commercial teas and cosmetics due to their phenolic properties. The antioxidant and pharmacological value... more
The leaves and twigs of the desiccation-tolerant medicinal shrub Myrothamnus flabellifolia are harvested for use in traditional and commercial teas and cosmetics due to their phenolic properties. The antioxidant and pharmacological value of this plant has been widely confirmed; however, previous studies typically based their findings on material collected from a single region. The existence of phenolic variability between plants from different geographical regions experiencing different rainfall regimes has thus not been sufficiently evaluated. Furthermore, the anthocyanins present in this plant have not been assessed. The present study thus used an untargeted liquid chromatography-tandem-mass spectrometry approach to profile phenolics in M. flabellifolia material collected from three climatically distinct (high, moderate, and low rainfall) regions representing the western, southern, and eastern extent of the species range in southern Africa. Forty-one putative phenolic compounds, p...
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The desiccation-tolerant shrub Myrothamnus flabellifolia has colonised a unique and harsh niche that provides little protection from the elements. It has a wide distribution range in southern Africa, occurring across an environmental... more
The desiccation-tolerant shrub Myrothamnus flabellifolia has colonised a unique and harsh niche that provides little protection from the elements. It has a wide distribution range in southern Africa, occurring across an environmental gradient that is exceptionally arid in the southwest and highly mesic in the northeast. It is also harvested for use in medicinal preparations, both traditionally and commercially. However, the phytochemical variability of plants from different rainfall regions has not been assessed, nor have the intraspecific relationships been evaluated by means of a rigorously tested phylogeny. The aims of the present study were thus (1) to test a phylogenetic hypothesis for intraspecific relationships in M. flabellifolia; (2) to assess, based on the global me-tabolomic profiles, whether accessions collected from the three different geographic locations in southern Africa across a rainfall gradient can be differentiated, and if this corroborates the phylogenetic signature; and (3) with the aid of multivariate statistical analysis, identify and evaluate the most significant discriminatory metabolites between the three sampled regions that could act as potential barcodes. The results show that the phylogenetic and metabolomic signatures were congruent, and the metabolomic data were better able to discriminate the different populations collected from the three regions. Several potential barcodes for discriminating the material from the three regions are proposed. Quercetin-rhamnoside and 3-O-methylquercetin, both significant anti-oxidants, were present at significantly higher quantities in the material from the driest region in the west than from the more mesic regions in the south and east, whereas quercetin-3-O-glucuronide was significantly higher in the latter. A naringenin-like compound or arbutin derivative could discriminate the southern samples from the eastern samples, whereas digalloylglucose differentiated the eastern samples from the southern samples. In summary, the findings of this study imply that the origin of the material should be considered when used in medicinal and cosmetic preparations.
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The orphan crop, Eragrostis tef, was subjected to controlled drought conditions to observe the physiological parameters and proteins changing in response to dehydration stress. Physiological measurements involving electrolyte leakage,... more
The orphan crop, Eragrostis tef, was subjected to controlled drought conditions to observe the physiological parameters and proteins changing in response to dehydration stress. Physiological measurements involving electrolyte leakage, chlorophyll fluorescence and ultra-structural analysis showed tef plants tolerated water loss to 50% relative water content (RWC) before adverse effects in leaf tissues were observed. Proteomic analysis using isobaric tag for relative and absolute quantification (iTRAQ) mass spectrometry and appropriate database searching enabled the detection of 5727 proteins, of which 211 proteins, including a number of spliced variants, were found to be differentially regulated with the imposed stress conditions. Validation of the iTRAQ dataset was done with selected stress-related proteins, fructose-bisphosphate aldolase (FBA) and the protective antioxidant proteins, monodehydroascorbate reductase (MDHAR) and peroxidase (POX). Western blot analyses confirmed protei...
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Xerophyta humilis is a poikilochlorophyllous monocot resurrection plant used as a model to study vegetative desiccation tolerance. Dehydration imposes tension and ultimate loss of integrity of membranes in desiccation sensitive species.... more
Xerophyta humilis is a poikilochlorophyllous monocot resurrection plant used as a model to study vegetative desiccation tolerance. Dehydration imposes tension and ultimate loss of integrity of membranes in desiccation sensitive species. We investigated the predominant molecular species of glycerolipids present in root and leaf tissues, using multiple reaction monitoring mass spectrometry, and then analysed changes therein during dehydration and subsequent rehydration of whole plants. The presence of fatty acids with long carbon chains and with odd numbers of carbons were detected and confirmed by gas chromatography. Dehydration of both leaves and roots resulted in an increase in species containing polyunsaturated fatty acids and a decrease in disaturated species. Upon rehydration, lipid saturation was reversed, with this being initiated immediately upon watering in roots but only 12-24 hr later in leaves. Relative levels of species with short-chained odd-numbered saturated fatty acids decreased during dehydration and increased during rehydration, whereas the reverse trend was observed for long-chained fatty acids. X. humilis has a unique lipid composition, this report being one of the few to demonstrate the presence of odd-numbered fatty acids in plant phosphoglycerolipids.
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Desiccation tolerance is common in seeds and various other organisms, but only a few angiosperm species possess vegetative desiccation tolerance. These 'resurrection species' may serve as ideal models for the ultimate design of... more
Desiccation tolerance is common in seeds and various other organisms, but only a few angiosperm species possess vegetative desiccation tolerance. These 'resurrection species' may serve as ideal models for the ultimate design of crops with enhanced drought tolerance. To understand the molecular and genetic mechanisms enabling vegetative desiccation tolerance, we produced a high-quality whole-genome sequence for the resurrection plant Xerophyta viscosa and assessed transcriptome changes during its dehydration. Data revealed induction of transcripts typically associated with desiccation tolerance in seeds and involvement of orthologues of ABI3 and ABI5, both key regulators of seed maturation. Dehydration resulted in both increased, but predominantly reduced, transcript abundance of genomic 'clusters of desiccation-associated genes' (CoDAGs), reflecting the cessation of growth that allows for the expression of desiccation tolerance. Vegetative desiccation tolerance in X....
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Leaf tensile strength was measured for the drought-tolerant grass Eragrostis curvula and the desiccation-tolerant grass E. nindensis when fully hydrated, partially dehydrated, naturally air-dried, and flash-dried. Leaf tensile strength... more
Leaf tensile strength was measured for the drought-tolerant grass Eragrostis curvula and the desiccation-tolerant grass E. nindensis when fully hydrated, partially dehydrated, naturally air-dried, and flash-dried. Leaf tensile strength increased in intact, air-dried leaves of E. ...
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Page 1. Received: 6 March, 2007. Accepted: 30 April, 2007. Invited Review Plant Stress ©2007 Global Science Books An Overview of Mechanisms of Desiccation Tolerance in Selected Angiosperm Resurrection Plants Jill M. Farrant Wolf Brandt... more
Page 1. Received: 6 March, 2007. Accepted: 30 April, 2007. Invited Review Plant Stress ©2007 Global Science Books An Overview of Mechanisms of Desiccation Tolerance in Selected Angiosperm Resurrection Plants Jill M. Farrant Wolf Brandt George G. Lindsey* ...
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Desiccation tolerance (DT, the ability of certain organisms to survive severe dehydration) was a key trait in the evolution of life in terrestrial environments. Likely, the development of desiccation-tolerant life forms was accompanied by... more
Desiccation tolerance (DT, the ability of certain organisms to survive severe dehydration) was a key trait in the evolution of life in terrestrial environments. Likely, the development of desiccation-tolerant life forms was accompanied by the acquisition of dormancy or a dormancy-like stage as a second powerful adaptation to cope with variations in the terrestrial environment. These naturally stress tolerant life forms may be a good source of genetic information to generate stress tolerant crops to face a future with predicted higher occurrence of drought. By mining for key genes and mechanisms related to DT and dormancy conserved across different species and life forms, unique candidate key genes may be identified. Here we identify several of these putative key genes, shared among multiple organisms, encoding for proteins involved in protection, growth and energy metabolism. Mutating a selection of these genes in the model plant Arabidopsis thaliana resulted in clear DT-, dormancy- and other seed-associated phenotypes, showing the efficiency and power of our approach and paves the way for the development of drought-stress tolerant crops. Our analysis supports a co-evolution of DT and dormancy by shared mechanisms that favour survival and adaptation to ever-changing environments with strong seasonal fluctuations.