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Drought is the primary challenge facing agricultural productivity and food sustainability productivity in Africa and many parts of the world. Very few higher plants, including crop plants, can survive periods of extended water loss. However, a small group of angiosperms, termed resurrection plants are able to lose up to 95% of their cellular water content in vegetative tissue upon extended periods of water, remain in an air-dry for months to years and regain full metabolic activity in the same tissue upon re-watering. The aim of this study was to investigate the changes in acyl chain composition within the major glycerophospholipids (in total and chloroplast suspension) and galactolipids (chloroplast suspension) at different stages of dehydration and rehydration treatments in the resurrection plant Xerophyta humilis (Bak) Dur and Schniz. This was done in order to ascertain their roles during acquisition of desiccation tolerance in X. humilis. The galactolipids and glycerophospholipids acyl chain compositions were determined by multiple reaction monitoring (MRM) mass spectrometry. The glycerophospholipids profiles from total leaves and roots lipid extracts showed an increased representation of unsaturated molecular species such as 18:3/18:3 (in leaves) and 18:3/18:2 (in leaves and roots) during dehydration, with a decrease in saturated and mono-saturated molecular species such as 16:0/16:0. Rehydration was associated with the opposite trend. Furthermore, increased representation of molecular species with unusual fatty acids were observed during dehydration, with the odd-numbered fatty acids such as 15:0, 17:0 and 19:0 increasing during dehydration and decreasing during re-watering. On the other hand, the 23:0 and 25:0 fatty acids decreased during dehydration and increased upon rehydration. Within the chloroplast profiles, the galactolipids (i.e. monogalactosyldiacylglycerolipids and digalactosyldiacylglycerolipids) showed maintenance of 18:3/18:3 and 18:3/18:2 molecular species during dehydration and rehydration. The phosphatidylglycerolipids profiles in the chloroplast, together with the uncommon chloroplastic glycerophospholipids such as phosphatidylethanolamine, phosphatidylcholine and phosphatidylinositol also showed an increase in the unsaturated molecular species during dehydration and decrease upon rehydration. Taken together, our data suggest that water deficit in X. humilis roots and leaves induce fatty acid unsaturation, as well as production of uncommon fatty acids. These unsaturated fatty acids may aid in maintaining membrane integrity during dehydration. This study shows that changes in lipid composition are part of the desiccation tolerance strategies used by X. humilis.

The use of metabolic fingerprints as taxonomic markers is becoming more common. Many studies have found that by comparing the vast metabolic fingerprints of closely related species to each other, secondary metabolites tend to be unique to the samples of individual species and are identified in clustering algorithms as the variables responsible for species-specific clustering. A holistic approach to metabolic fingerprinting was thus employed to assess the stability of various metabolomic markers and finally to distinguish taxonomically difficult Aizoaceae species. Many secondary metabolites are not constitutively produced. Because at least some Aizoaceae species facultatively use crassulacean acid metabolism (CAM), there was a potentially interesting molecular switch that could be monitored for transitions in metabolic fingerprints. In order to contextualise the changes in carbon uptake, 20 different climate, nutrient, physiological, and other variables were monitored over the course of 12 months to build up a store of species-specific information to use in model optimisation across 5 Aizoaceae species (Galenia africana, Aridaria noctiora, Carpobrotus edulis, Ruschia robusta, and Tetragonia fruticosa) using two Crassulaceae species as CAM controls (Cotyledon orbiculata and Tylecodon wallichii ). Metabolic fingerprints of the leaves of various Aizoaceae species were generated using LC/TOFMS, following which Principal Components Analysis (PCA) was used to identify the LC-MS ions which distinguished the species from each other, or in statistical terms, were informative. Once isolated, this subset of informative data was established as metabolic barcodes for the identification of the study species. A machine learning algorithm, Random Forest, was used to build a classification model based on the metabolic barcodes which was then trained on various trends from the factors monitored over the year. The use of these trends in the development of a classification model based on metabolic barcodes resulted in a highly robust classification model for species identification. Clustering analysis of a subset of ions which corresponded to compounds previously isolated from Aizoaceae species did not show species-specific clustering and was inevitably biased by compounds from species with a greater number of studies focusing on compound isolation. Ideally, this model should be expanded to include other species from the Aizoaceae family to further check robustness of the model. Application of this model to these and other species could facilitate not only species identification and distribution, but also the identification of novel chemical constructs associated with particular species.

In response to abiotic stresses, organisms throughout the plant kingdom, as well as microorganisms and micro-animals such as nematodes or tardigrades, have been observed to express Late Embryogenesis Abundant (LEA) proteins as protective mechanisms. However, despite two decades of research, little is understood about their physiological functions and this has led to extensive nomenclature, with a large amount of redundancy. The primary reason for this lack of insight into LEA protein functions is their highly hydrophilic and intrinsically disordered nature. Intrinsically disordered proteins (IDPs) cannot be studied using conventional methods of structural analyses such as X-ray crystallography and, therefore, alternative techniques are required. A combination of transgenic and in vitro studies have also shown that LEA proteins are most likely to behave as molecular chaperones by binding water and ions, preventing macromolecular aggregation and protecting enzymatic activity during dehydration. This study characterized two dehydrins that were expressed during dehydration in the desiccation tolerant plant, Xerophyta humilis. From a transcriptome analyses on X. humilis, cDNA for the two dehydrins were obtained. These sequences were first analysed using various in silico tools in order to identify putative dehydrin-specific characteristics. Subsequently, these two dehydrins were cloned and expressed for production of recombinant dehydrin protein. These proteins were then analysed in terms of structural and functional characteristics. Structurally, through the use of circular dichroism in an in vitro system, both dehydrins demonstrated the shift towards being increasingly alpha-helical when placed in environments of decreasing water content. The role of these two dehydrins in stabilizing enzymes during dehydration was subsequently investigated using citrate synthase (CS) and lactate dehydrogenase (LDH). The preservation of enzyme activity was observed in both CS and LDH. This preservation of enzyme activity was further maintained by the presence of trehalose. Anti-aggregation roles were also investigated, however, neither dehydrin demonstrated significant ability to minimize the aggregation of LDH. This study hopes to establish a pipeline for characterizing LEA proteins using structural and functional assays in order to provide alternative means of LEA protein classification.

Includes bibliographical references, Eragrostis tef, commonly known as tef, is an important staple food and forage crop indigenous to Ethiopia. Tef plants are highly adaptable to abiotic stress conditions and are able to grow and produce grain yields under a wide range of environmental conditions, particularly under drought stress. In this study, tef plants were subjected to controlled dehydration stress treatment and physiologically characterised using relative water content (RWC), electrolyte leakage and chlorophyll fluorescence measurements, to establish critical water content stages for investigation of changes to the tef proteome in response to dehydration stress. Physiological testing showed tef viability to be retained to 30% RWC, however, further water loss to below 30% RWC, resulted in total loss of viability. Physiological characterisation with dehydration treatment showed a maximum leakage rate of 780 μS.min-¹.gdw-¹ and complete photosynthetic disruption with Fv/Fm and ɸPSII values decreasing to 0.2, below 30% RWC. Additionally, ultra-structural analysis using transmission electron microscopy showed extensive damage to the subcellular organisation of tef plant cells at water contents below 30% RWC. Based on these physiological data, it was decided to investigate the proteome of tef leaf dehydrated tissues at 50% RWC, as a non-lethal dehydration stress, as compared to hydrated tissues at 80% RWC. Proteomic analyses using iTRAQ mass spectrometry coupled to peptide OFFGEL fractionation and appropriate database searching with the Tef Extended and Liliopsida databases enabled the generation of three dataset results. These datasets, each contained a substantial amount of database matched proteins, where 5727 proteins for the Tef Extended (TE), 2656 proteins for the Tef Extended unique (TEU) and 4328 proteins for the Monocot unique (MU) datasets, were identified. Statistical analyses on peptide relative quantification values showed differential regulation of 211 proteins for the TE dataset, 111 proteins for the TEU dataset and 174 proteins for the MU dataset, in response to dehydration stress. A reciprocal BLAST search through the use of OrthoMCL with all three differentially regulated datasets (foregrounds) showed the TE foreground to provide the most comprehensive total protein coverage for further bioinformatics inference. Bioinformatics analysis using the programs Mercator, MapMan and Blast 2GO showed a diverse range of biological processes, where functional enrichment of GO-terms involved in biotic and abiotic stress response, signalling, transport, cellular homeostasis and pentose metabolic processes were enriched in tef high-abundance proteins. GO-terms linked to ROS producing processes such as photosynthetic reactions, cell wall catabolism, manganese transport and homeostasis, the synthesis of sugars and cell wall modification were enriched in tef low-abundance proteins. Additionally, KEGG analysis was used to observe tef proteins mapped to various biological pathways, of which the stress-responsive pathways, glutathione metabolism and ascorbate and aldarate metabolism were analysed in depth. Furthermore, biological validation of a few high-abundance proteins generated from iTRAQ analysis in the form of western blotting and relevant enzyme assays were conducted. The results showed the proteins fructose-bisphosphate aldolase (FBA), glutamine synthetase (GLN), functioning in plant maintenance 2 processes as well as the stress-protective antioxidant proteins, monodehydroascorbate reductase (MDHAR), peroxidase (POX) and superoxide dismutase (SOD) to be accumulated and further support iTRAQ findings. To date, this is the first study that has investigated the proteome profile of tef in response to dehydration.

Studies on resurrection plants and other anhydrobiotic organisms, have shown that Late Embryogenesis Abundant (LEA) proteins are expressed upon the onset of desiccation and are therefore inferred to be associated with the desiccation tolerance response. To date, despite some 25 years of research on these proteins, there is still very little understanding of the physiological function(s) of the majority of LEAs. This is because they lack tertiary structure in the hydrated state, making assigning of physiological roles difficult. This MSc study was undertaken to investigate the gene expression of a set of 21 putative LEAs during dehydration and subsequent rehydration stress, in the resurrection plant Xerophyta humilis (Baker). Recombinant proteins were expressed for 3 of the LEA genes from this set in order to perform structural studies and to ascertain their LEA status. These studies were conducted with the purpose of shedding light on the role of LEAs in desiccation tolerance, to add to the ever-growing transcriptomic and proteomic data, and to the current knowledge of these enigmatic proteins. Quantitative real-time gene expression (qPCR) analysis was conducted on the set of 21 full length X. humilis cDNA clone nucleotide sequences, with similarities to late embryogenesis mRNA sequences, derived from a study conducted by Collett et al., (2004). Expression analysis was conducted in both leaves and roots, across a dehydration and rehydration profile of X. humilis. Of this total group of 21 full length cDNA clones, three LEAs; XhLEA2-3 and XhLEA2-6 (two putative Group 2 LEA genes) and XhLEA3-5 (a putative Group 3 LEA gene), were chosen for cloning and expression studies. cDNAs of these XhLEAs were cloned into a modified bacterial expression vector and recombinant protein expression was attempted in E. coli.

Includes bibliographical references, As there is limited information on the mechanisms of vegetative desiccation-tolerance in resurrection plant rhizomes, this work was undertaken to study the mechanisms of desiccation-tolerance in Mohria caffrorum rhizomes. Fronds of this plant have been previously characterized as being desiccation-tolerant in summer and desiccation-sensitive in winter. Since fern rhizomes are perennial organs, it was of interest to establish whether these organs are also perennially desiccation-tolerant and, whether or not the rhizomes regulate desiccation-tolerance in the fronds. Ultra-structural evidence using transmission electron microscopy and viability studies using electrolyte leakage analysis showed that the rhizomes were desiccation-tolerant throughout the seasons. Quantitative proteomics analysis using isobaric tags for relative and absolute quantification was employed to investigate molecular mechanisms of desiccation-tolerance in the rhizomes of this plant. Using a custom fern rhizome specific peptide sequence database, 236 proteins were identified. Of these, 16 proteins increased in abundance while 14 declined, in the summer collected rhizomes. On the other hand, 16 proteins increased in abundance and 20 declined in the winter form. Western blot analysis confirmed the expression trends of heat shock protein 70-2 and superoxide dismutase-[Cu-Zn], which were among the differentially expressed proteins. Bioinformatics analysis of the differentially expressed proteins was carried out using network enrichment tools, to identify key molecular processes and pathways involved in the rhizome response to desiccation stress. Results indicate that the rhizomes use different molecular mechanisms to achieve desiccation-tolerance in winter and summer. Potential cross-talks and cross-tolerances were identified in which mechanisms protecting the rhizomes against desiccation-tolerance appeared to also protect them against heat stress, and in winter an apparent cross-talk against desiccation and pathogen stresses was also identified. This study is the first report of evidence that M.caffrorum rhizomes are the 'master-regulator organs' responsible for regulating desiccation-tolerance in the fronds. This role was inferred from the rhizome's predicted up-/down-regulation of biological processes and pathways that relate to leaf senescence, shoot system morphogenesis and gametophyte development, among others.

Includes bibliographical references, Resurrection plants are unique in the ability to survive near complete water loss in vegetative tissues without loss of viability. In order to do so, they employ multifaceted strategies which include structural adaptations, antioxidant and photoprotective mechanisms, and the accumulation of proteins and metabolites that stabilise macromolecules. A full understanding of the phenomenon of vegetative desiccation tolerance will require a systems view of these adaptations at the levels of the genome, the control of gene expression, and the control of metabolic pathways. This dissertation reports a high-throughput metabolomic analysis of the changes that occur in vegetative tissues of resurrection plant Xerophyta humilis during dehydration. A combination of chromatography, mass spectrometry and nuclear magnetic resonance revealed numerous primary and secondary metabolites in the plant. Multivariate statistics identified a subset of metabolites that were significantly up- or down-regulated in response to water deficit stress. These metabolites both confirmed existing observations about the metabolic response of X. humilis to drying and revealed compounds not previously known to be associated with this response. Desiccation-associated metabolites were mapped onto known biochemical pathways, to generate hypotheses concerning possible regulatory schemes in the stress response, inviting deeper investigation in future.

Includes abstract., Includes bibliographical references., There is a growing interest in legumes and legume based foods because of the health claims associated with their consumption. The aim of the current study was to explore the nutraceutical potential of bambara groundnuts (Vigna subterranea L. Verdc) and common beans (Phaseolus vulgaris L.) commonly grown in Zambia based on the antioxidant properties and phenolic phytochemical profiles. Two market classes of bambara groundnuts (red and brown) and four of common beans (red, grey mottled, brown and white) were screened in raw dry form. Effects of cooking and sprouting on the antioxidant activities and phenolic phytochemicals of the promising market classes were assessed. The study employed in vitro antioxidant assays (DPPH and FRAP) to screen for antioxidant properties, HPLC-PDA-ESI-MS and Folin Ciocalteu assay to screen for phenolic phytochemical profiles.

The monocotyledonous Xerophyta viscosa belongs to a unique group of angiosperms known as resurrection plants. These plants possess a number of unique characteristics which allow them to survive and cope for extended periods with extreme abiotic stresses such as dehydration and cold stress. It is therefore of great interest to understand and elucidate the various molecular mechanisms which are specifically regulated in response to abiotic stress by identifying genes and proteins which may contribute to abiotic stress tolerance. These genes could potentially be utilized in the development of crops with improved tolerance to abiotic stresses. The aim of this study was to preliminarily characterize XvGolSII, a galactinol synthase, which had been isolated from a X. viscosa cold stress cDNA library. In this study, the XvGolSII cDNA was sequenced and both the nucleic and amino acid sequence analysed through in silico analysis. The XvGolSII cDNA sequence was shown to be 1434 bp in length, with an open reading frame (ORF) of 1018 bp. This ORF encodes a 339 amino acid protein with a molecular weight of 38.7 kDa, containing a characteristic hydrophobic carboxyterminal pentapeptide, APSAA. Recombinant XvGolSII protein was successfully expressed in E. coli BL21 cells using the pET29b expression vector. The recombinant XvGolSII protein showed in vitro galactinol synthase activity via an activity assay using HPAEC-PAD, where it produced galactinol from the substrates myo-inositol and UDPgalactose. Subcellular localisation examination, using an XvGolSII-YFP fusion protein, indicated localisation to the cell membrane of onion epidermal cells. Quantitative real time PCR analysis showed XvGolSII to be significantly down-regulated during dehydration stress while mildly up-regulated during the early stages of cold stress, though the latter increase was not significant. Western blot analyses did not detect XvGolSII in total protein extracted from X. viscosa leaf tissue during dehydration and rehydration treatments, using polyclonal antibodies generated from the XvGolSII recombinant protein. This study successfully characterized XvGolSII at the molecular level and provides a basis for further investigation of the role of XvGolSII in abiotic stress tolerance.

In order to conduct proteomic analysis on the hydrated root tissues of the resurrection plant, Xerophyta viscosa Baker, aeroponically grown plant roots were subjected to various proteomic techniques. Three protein extraction methods were investigated, of which one method, was the most suited in isolating total protein from the root tissues of X. viscosa.

The findings presented in this study give evidence for an ABA-mediated stomatal closure in response to initial dehydration of X. humilis, however, from 60% RWC onwards, stomata were observed to open again. This supplies further support for the hypothesis that resurrection plants actively lose water once protection is accumulated in order to minimize ROS activity and put a stasis on unregulated metabolism.

Includes abstract., Includes bibliographical references (leaves 75-86)., The presence and expressIon patterns of orthologues of LEA group 1 genes has been characterised in the resurrection plant, Xerophyta humilis. The group I LEAs (Em I and Em6) were first identified as proteins that were abundantly and specifically expressed during the desiccation and germination phase of angiosperm seed development. The group I LEA genes are characterised by the presence of one or more tandemly repeated 20-amino acid motifs that are particularly rich in Gly residues.

Includes abstract. Includes bibliographical references (leaves 170-198).

Includes abstract., Includes bibliographical references (leaves 172-191)., Has accompanying material on CD., The resurrection plant, Xerophyta humilis is used as a model system to identify and characterise genes which play an important role in conferring desiccation tolerance in plants. In this study, the expression of a novel gene named desiccation induced-1 (dsi-1VOC) during desiccation in X. humilis and desiccationsensitive plants is characterised.

Includes abstract., Includes bibliographical references (leaves 131-169)., The ability of tissues to survive almost complete loss of cellular water is a trait found throughout the plant kingdom. While this desiccation tolerance is common in seeds of most angiosperms it is rare in their vegetative tissues. Xerophyta humilis (Bak.) Dur and Schintz belongs to a small group of resurrection angiosperms and it possesses the ability to withstand extreme desiccation of greater than 90% in both its seeds and vegetative tissues and return to active metabolism upon rehydration. We have tested the hypothesis that vegetative desiccation tolerance in angiosperms has evolved as an adaptation of seed desiccation tolerance.

Stomatal apertures on leaves of the resurrection plant Xerophyta humilis were monitored microscopically in order to characterize stomatal regulation during a dehydration time course. In addition, the effect of exogenous application of the stress hormone ABA on stomatal regulation was followed. X humilis stomatal regulation appears to be initially similar to that typical of desiccation sensitive plants, but differed in that stomata did not all close at once but at a slower rate to control the drying rate of the plant, this gave time for protection mechanisms to be laid down. The signal hormone ABA was found to have strong stomatal control on the adaxial surfaces of leaves but weak control on the abaxial leaf surfaces, thus it is difficult to say that ABA regulates the process until RWC of below 50%, where stomatal apertures open as a result of shrinkage of guard cells due to loss of water.

Includes bibliographical references (leaves 59-71)., A number of genes up-regulated in response to abiotic stress have been isolated from X. viscosa by various methods, one of which includes differential screening of cDNA libraries. Of these genes, a large number are undescribed, with no identity to known plant genes. Two such genes, XvRG6 and XvRF17, isolated from a X. viscosa cDNA library have been partially characterised. Southern blot analysis confirmed the presence of both XvRG6 and XvRF17 genes in the X. viscosa genome. In silico analyses predicted XvRG6 to be proline-rich protein, since it possesses many of the features common to PRP such as a signal peptide, proline repeats, a cysteine residue and possible phosphorylation sites. It also possesses a tyrosine residue present in some of the repeats, and this residue is belivied to play a role in protecting the plant against environmental stresses. The XvRF17 protein was predicted by in silico analyses to belong to the family of metallothioneins, a family of metal-binding proteins. Anaylis of the XvRG6 mRNA transcript showed that the gene was not dehydration stress inducible, but was induced by ethylene, endogenous ABA, SA and JA application. In contrast, the XvRF17 mRNA transcript was shown by RT-PCR to be induced by dehydration stress, endogenous ABA, SA and JA application but not by ethylene treatment. Interestingly, western blot analyses revealed that XvRG6 protein levels increased only during dehydration and not during any other imposed stress. This study has shown that both XvRG6 and XvRF17 and responsive to stress. Since there are no known orthologues of these genes, their respective roles in X. viscosa remains speculative.

Includes abstract., Includes bibliographical references (leaves 170-209)., The Xerophyta viscosa aldose reductase cDNA (XvAld1) was isolated from a dehydration library. Gene transcripts that are upregulated during stress are normally involved in protection and/ or adaptation, leading to stress tolerance. The genomic organisation of XvAld1 was characterised using Southern blot analysis and DNA sequencing. The results revealed more than one copy of the gene with a complex banding pattern that was partially resolved by sequencing. The sequencing of PCRamplified genomic clones showed that the gene is organised into nine exons and eight introns spanning ~2.9 kb. The observed nucleotide differences between the sequenced clones could reflect polymorphisms between different copies of the gene. An 870-bp clone of the 5′ untranslated region, matching the 5′ leader sequence on the XvAld1 cDNA was analysed for cis-acting response elements. Many of the sequence motifs matched those for hormonal regulation, organ specific expression, dehydration, high or low temperature responses, light and phytochrome responsiveness, wounding, as well as G-box, CAAT and TATA-boxes.

Includes bibliographical references., The waste streams from the pineapple canning industry are a valuable source of carbohydrates, in particular dietary fibre (DF) and neutral sugars. In addition, the waste is a suitable source of antioxidants, enzymes such as bromelin and flavours. Since this waste (core and peel) is currently sold at minimal cost to cattle farmers for use as cattle feed or compost, alternative uses of the material with commercial potential was investigated.

Includes bibliographical references (p.143-164)., In the field C. wilmsii (homoiochlorophyllous) and X humilis (poikilochlorophyllous) plants do not experience drought longer than two and six months, respectively. In this study longevity of dry C. wilmsii and X. humilis plants was investigated for up to 10 months under four different sets of conditions. Some conditions resembled those under which the two species would experience drought in the field, but also included those that resemble the accelerated aging conditions used in seed studies.

Vegetative desiccation tolerance is the ability of a plant to dry to equilibrium with its surrounding atmosphere and remain in this dry state for prolonged periods of time. Upon rehydration, these plants are able to regain full physiological functionality. Vegetative desiccation tolerance is common and partially understood in the less complex clades including the algae, bryophytes and lichens but is uncommon in the vascular land plants. Vegetative desiccation tolerance is partially understood in the angiosperms but there has been little work on desiccation tolerance in pteridophytes Mohria caffrorum (L.) Desv is one such desiccation tolerant pteridophyte This fern has the unique characteristic of having both desiccation tolerant and desiccation sensitive forms, which alternate seasonally, which this study is the first to show. We show here that; 1) M caffrorum is indeed a desiccation tolerant fern. 2) M. caffrorum has desiccation tolerant and desiccation sensitive frond types. which are morphologically distinct. 3) These morphological differences are directly related to the ability to survive desiccation as well as playing a role in tine ecologies of the two growth forms. 4) The spores of M. caffrorum are also desiccation tolerant. A hypothesis is proposed detailing why M. caffrorum is able to change between being desiccation tolerant and desiccation sensitive.

Includes bibliographical references (p. 160-191)., Resurrection plants are unique in that their vegetative tissue has the ability of survive reversible dehydration to an air-dry state. The widespread African resurrection plant Myrothamnus flabellifolia (Welw), woody shrub, is one of the largest of these plants. In addition to its resurrection ability it is also an important medicinal plant and is used by local tribes in the various regions where it grows to treat a wide variety of ailments. This thesis has investigated a number of morphological, ultrastructural and biochemical adaptations of the leaves of M. flabellifolia to dessication and associated stresses. The main aim of this thesis was to ascertain the role of polyphenols and the cell wall of M. flabellifolia in relation to its desiccation tolerance.

Includes bibliographical references (leaves 44-54)., Genes that are upregulated in the early response to stress are not well understood. ERD15 (early-responsive to dehydration) in Arabidopsis and its homologues in various other plants have been shown to be upregulated within I hr post-exposure to dehydration and high salinity stress treatments. There is however limited literature on the functionality of ERD15. A cDNA showing homology to ERD15 was isolated from a library generated by low temperature stress treatment of Xerophyta viscosa and was subsequently named XvERD15.

By differential screening of a cDNA library of the resurrection plant Xerophyta viscosa, a cDNA termed XvPer I was isolated for its over-expression under dehydration stress. Analysis of the cDNA sequence indicated a hydrophilic protein of a predicted Mw of 24.2 kDa with high identity to plant l-Cys peroxiredoxins, a novel antioxidant enzyme. Southern blot analysis revealed that XvPer I was most probably a single copy gene. The polypeptide sequence had significant identities (-70%) with other recently identified plant I-Cys peroxiredoxins with an absolutely conserved active site (PVCTTE). The protein sequence also had a putative bipartite nuclear localization signal.

Includes bibliographical references (leaves 61-70).

Includes bibliographical references., Myo-inositol I-phosphate synthase (INO 1) catalyses the conversion of glucose-6-phosphate to myo-inositol I-phosphate, which is subsequently dephosphorylated to myo-inositol. Myo-inositol is a precursor for a number of important metabolites that include membrane components, storage molecules, phytohormones and a variety of osmoprotectants. Xerophyta viscosa Baker (Family Velloziaceae) is a monocotyledonous angiosperm which has the ability to resume full physiological function after desiccation. The full-length cDNA for INO1 from X viscosa was isolated using the RACE technique.