O melhoramento genético clássico de sementes milho (Zea mays L.) permitiu desenvolver inúmeras variedades, incluindo o milho com qualidade proteica melhorada (Quality Protein Maize, QPM), que visava aumentar os teores proteicos e as propriedades nutricionais. Por outro lado, novas variedades comerciais foram obtidas por vegetais geneticamente modificados (GM), com foco em parâmetros agronômicos. Em ambos os casos, a segurança dessas variedades para uso como alimento é uma das principais preocupações dos desenvolvedores e dos órgãos de regulamentação. A Equivalência Substancial é a base do sistema de avaliação da segurança de culturas geneticamente modificadas, no entanto alterações na expressão de proteínas não são devidamente analisadas e esclarecidas. As abordagens proteômicas complementam as técnicas de avaliação de biossegurança para alimentos GM, bem como permitem investigar possíveis efeitos indesejáveis derivados do melhoramento clássico. Os objetivos do presente estudo foram caracterizar e comparar os perfis proteicos de variedades de milhos convencionais melhorados (QPM) e geneticamente modificados (GMs), contra suas respectivas linhas convencionais utilizando técnicas proteômicas como eletroforese bidimensional (2-DE) e bottom up shotgun (gel-free). Num primeiro estudo, foram utilizadas três amostras de milho, sendo duas variedades convencionais com QPM (QP1 e QP2) e uma variedade convencional normal (CN). No segundo estudo, foram analisadas duas cultivares de milho GM (GM1 e GM2) e seus respectivos convencionais genitores (CG1 e CG2). As composições químicas de todas as amostras também foram avaliadas quanto a Equivalência Substancial. O extrato bruto proteico foi submetido à análise de eletroforese unidimensional (1-DE), bidimensional (2-DE) e bottom up shotgun (gel-free). As imagens dos mapas proteicos foram analisadas pelo software Image Master 2D Platinum 7.0 (GE). Os spots diferencialmente expressos e selecionados foram sequenciados por MS. Pela composição química das principais frações das amostras de milho foi possível identificar a equivalência substancial entre as amostras convencionais e GMs, bem como QPMs e sua convencional dentro das faixas de variabilidade esperadas da espécie. Nos géis 1-DE foram observadas bandas proteicas com perfis similares entre os grupos de amostras avaliadas para ambos estudos. Nas imagens dos géis 2-DE não houveram alterações extremas entre as amostras de milhos GMs e seus respectivos convencionais genitores (CGs), mas apenas diferenças na intensidade dos spots proteicos. As variedades QPMs e CN apresentaram diferenças devido à distribuição dos spots. Os mapas proteicos das amostras CG1 x GM1 e CG2 x GM2 apresentaram maior semelhança com porcentagens de matchings superiores a 70 %, enquanto as porcentagens de matchings entre variedades diferentes (QPMs e CN) foram menores. No total foram identificadas 219 proteínas das amostras CGs x GMs e QPMs x CN, classificadas quanto aos seus processos biológicos e função molecular. Em conclusão, foram encontradas diferenças entre os cultivares GMs e CGs, indicando uma variação normal entre variedades de milho, que não comprometem a segurança alimentar das amostras estudadas. Quanto às amostras com QPM e CN as diferenças encontradas são devido à sua distância nas linhagens ou germoplasma. / The classic genetic breeding of corn seeds (Zea mays) has enabled the development of many varieties, including corn with improved protein quality (Quality Protein Maize, QPM), which aimed to increase protein levels and nutritional properties. On the other hand, new commercial varieties have been obtained out of genetically modified (GM) vegetables, with a focus in agronomic parameters. In both cases, the safety of these varieties for food use is one of the main concerns for the developers and for the regulatory agencies. Substantial Equivalence is the basis of the safety evaluation system for genetically modified crops, however, alterations in the protein expressions are not been properly analyzed and clarified. The protein approaches complement the techniques of biosafety evaluation for GM foods, as well as allow for possible undesirable effects derived from classic improvement to be investigated. The goals of the current studies were to characterize and compare the protein profiles of the different varieties of conventionally improved (QPM) and genetically modified (GM) corn, against their respective conventional lines using proteomic techniques, such as, two-dimensional electrophoresis (2-DE), bottom up shotgun (gel-free) and masses spectrometry (MS). In a first instance of the study, three samples of corn were used, two of conventional varieties with QPM (QP1 and QP2) and one conventional normal variety (CN). In a second instance of the study, two cultures of GM corn (GM1 and GM2) were analyzed and their respective conventional genitors (CG1 and CG2). The chemical compositions of all the samples were also evaluated for their Substantial Equivalence. The protein raw extract was submitted to analysis of one-dimensional (1-DE), two-dimensional (2-DE) electrophoresis, and bottom up shotgun (gel-free). The protein image maps were analyzed by the Image Master 2D Platinum 7.0 (GE) software. The spots which were expressed and selected differentially were sequenced by MS. By the chemical composition of the main fractions of the samples of corn, it was possible to identify the substantial equivalence between the conventional samples and GMs, likewise with OPMs and their conventional in the ranges of variability which were expected for the species. On the 1-DE gel, it was observed protein bands with similar profiles amongst the groups of evaluated samples for both studies. In the images of the 2-DE gel, there were no alterations between the GM corn and their respective conventional genitors (CGs), but only differences in intensity of the protein spots. The OPM and CN varieties presented differences due to the distribution of the spots. The protein maps of samples CG1 vs. GM1 and CG2 vs. GM2 presented greater similarities with the percentages of matchings superior to 70%, while the percentage of matchings among different varieties (QPMs and CN) were smaller. In total, there were 219 proteins identified in the samples CGs vs. GMs and QPMs vs. CN, classified by the biologic processes and molecular function. In conclusion, there were found differences between the cultures of GMs and CGs, indicating a normal variation among the corn varieties, which do not affect the food security of the studied samples. As per the samples with QPM and CN, the differences found were due to the line distances or germplasm.

Thesis (D. Tech.: Biotechnology)-Dept. of Biotechnology, Durban University of Technology, 2006 xii, 274 leaves / In Sub-Saharan Africa there is an urgent need to sustain and improve the quality of its food resources. Poverty eradication features high on the agenda of a number of world health organisations, while the number of underweight children in Africa continues to increase (Pellet, 1996). Providing nutritionally enhanced foods to the poor will help towards achieving this objective. Protein-energy malnutrition has been identified as one of the most important problems facing Africa, with maize as the staple diet (Nkama et al., 1995). However, a combination of several factors limits availability and the nutritional quality of maize. During starvation, energy and protein intakes decrease by 20-30%, with most of the children in Africa having an average protein intake of only 20 g per day (Igbedioh, 1996). Energy availability also affects protein utilization because of interrelationships of protein and energy metabolism (Elwyn, 1993). The diets of inhabitants in developing regions depend mainly on cereals (maize) for both protein and dietary energy which lacks indispensable amino acids, minerals, vitamins and carbohydrates. In light of these growing concerns an attempt was made to devise a scientific strategy to combat the nutritional shortfalls of maize meal. A multidisciplinary and concerted approach was followed within this project aimed at designing an improved thermostable amylase and applying the enzyme to nutritionally enhance maize meal. It was envisaged that the manipulation of maize meal, by the application of enzyme technology will improve the nutritional status of this staple food. The consequences is that an alternate solution for the eradication of an ailing, poverty stricken and malnourished African population is achievable. It is possible that the boundaries defining the limits of life will extend to even greater extremes through the application of novel technologies.

Thesis (MA)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: The development of the global biotechnology industry largely coincided with the development of the US biotechnology industry. This resulted in this industry's oligopolistic and centralised nature where only a few multinational chemical and pharmaceutical companies control most biotechnology processes and production of commodities emanating from these processes. The governance of biotechnology has, until recently, been dominated by state actors who have endeavoured to secure national interests, including those of large multinational corporations (MNCs) based within their boundaries. The technological ability of developed states to exploit and use unevenly distributed resources to their advantage means that an uneven relationship exists between these and poor developing countries. This has been highlighted by differences in public opinion about the role and application of biotechnology in society. While some opinions favour the use and application of biotechnology to enhance food supplies and boost production levels and trade, other opinions caution against the possible hazards that genetically manipulated organisms (GMOs) hold for the environment and human existence. The commercialisation of biotechnology has resulted in the exponential growth of genetically manipulated crops in especially the United States and countries like Argentina and Canada. These countries produce large surpluses of staple grains such as corn and soya and try to sell these to countries with food supply problems. The clash in commercial interests stemming from developed countries' insistence on the protection of intellectual property rights (IPR) on genetically manipulated (GM) seeds has caused considerable conflict with poor farmers who will not be able to sustain their livelihoods if they cannot save seeds for future harvests. This is one aspect of the problems surrounding the protection of knowledge products that is exacerbated by the scientific uncertainty pertaining to the risk involved with biotechnology. While some observers agitate for precaution with the use of GMOs, others feel that a lack of scientific proof of harm is sufficient grounds for proceeding with developments in biotechnology. Conversely, there are some that feel that biotechnology is market driven instead of human needs driven, ultimately resulting in developing countries receiving very little benefit from it. The Cartagena Protocol on biosafety was drafted to address some of the difficulties involved with the transboundary movement of GMOs. Although it holds very specific advantages for developing countries, as a regulatory framework it is limited in its scope and application. Developing countries are limited in their policy options to address their need to protect biodiversity and secure their food supply. This means that considerable challenges and constraints await these countries in utilising global governance of public goods and building their human and technological capacities. / AFRIKAANSE OPSOMMING: Die ontwikkeling van die globale biotegnologie-industrie het grootliks saamgeval met die ontwikkeling van die Verenigde State se biotegnologie-industrie. Dit het aanleiding gegee tot hierdie industrie se oligopolistiese en gesentraliseerde aard waar slegs enkele multinasionale chemiese en farmaseutiese maatskappye die meeste biotegnologie prosesse en die vervaardiging van kommoditeite uit daardie prosesse beheer. Die regering van biotegnologie was tot onlangs oorheers deur staatsakteurs wie gepoog het om nasionale belange te beskerm, insluitend die belange van multinasionale korporasies (MNK) wat vanuit hulle grondgebied funksioneer. Die tegnologiese vermoë van ontwikkelde state om oneweredig verspreide hulpbronne tot eie gewin te benut beteken dat 'n ongelyke verhouding bestaan tussen hierdie en arm ontwikkelende state. Dit word beklemtoon deur verskille in openbare mening oor die rol en aanwending van biotegnologie in die samelewing. Terwyl sekere opinies ten gunste van die aanwending van biotegnologie vir die verbetering van voedselbronne en produksievlakke en handel is, dui ander opinies op die moontlike gevare wat geneties gemanipuleerde organismes (GMOs) vir die omgewing en menslike voortbestaan inhou. Die kommersialisering van biotegnologie het gelei tot die eksponensiële groei van geneties gemanipuleerde gewasse in veral die Verenigde State en state soos Argentinië en Kanada. Hierdie state produseer groot hoeveelhede stapelgrane soos mielies en soja en poog om dit te verkoop aan state met voedselvoorsieningsprobleme. Die botsing in kommersiële belange wat spruit uit ontwikkelde state se aandrang op die beskerming van intellektuele eiendomsreg op geneties gemanipuleerde saad veroorsaak beduidende konflik met arm landbouers wie nie hulle lewensonderhoud kan verseker as hulle nie saad kan berg vir toekomstige saaiseisoene nie. Dit is een aspek van die problematiek rondom die beskerming van kennisprodukte wat vererger word deur die wetenskaplike onsekerheid wat gepaard gaan met die risiko's van biotegnologie. Terwyl sekere waarnemers vir waaksaamheid pleit in die gebruik van GMOs, is daar ander wat voel dat 'n gebrek aan wetenskaplike bewyse van skade genoegsame gronde is vir die voortsetting van ontwikkelings in biotegnologie. Insgelyks is daar diegene wat meen dat biotegnologie markgedrewe in plaas van menslike behoefte gedrewe is, wat uiteindelik daartoe lei dat ontwikkelende state baie min voordeel daaruit trek. Die Kartagena Protokoloor bioveiligheid is opgestel om van die probleme betrokke by die oorgrens verskuiwing van GMOs aan te spreek. Hoewel dit spesifieke voordele vir ontikkelende state inhou is dit as reguleringsraamwerk beperk in omvang en aanwending. Ontwikkelende state het beperkte beleidsopsies om hulle behoefte om biodiversiteit te beskerm en voedselvoorsiening te verseker, aan te spreek. Dit beteken dat beduidende uitdagings en beperkings hierdie state in die benutting van globale regering van openbare goedere vir die bou van menslike en tegnologiese kapasiteite in die gesig staar.

Primordial germ cells (PGCs) are the embryonic precursors of the germ cell lineage. Segregation of the chicken germ line from somatic cells occurs very early in embryonic development. By day two of incubation chicken PGCs can be isolated from the circulating blood. The in vitro culture of chicken PGCs has significant potential as a tool for the investigation of germ cell development and as a cell-based system for the production of genetically modified chickens. The isolation, culture and manipulation of migratory chicken PGCs reported previously have not been independently validated. Initial attempts to isolate and culture chicken PGCs by reproducing a published protocol proved difficult. Key components of the published culture medium are by their nature variable, including the use of BRL-conditioned medium and animal sera. The protocol also stated that addition of SCF to the culture medium is essential but did not identify the source of SCF used. Several components of the culture conditions were tested including sources and batches of bovine and chicken sera and the growth factors FGF2 and SCF. Chicken PGCs from wild type and GFPexpressing chicken embryos were cultured and several cell lines established, proliferating for more than 100 days in culture. After seventy days in culture a single chicken PGC cell line was shown to retain the potential to develop into functional sperm. This was demonstrated by injection of the cultured chicken PGCs into early chick embryos, which were hatched and produced offspring derived from the injected chicken PGCs. To understand and produce a more robust system for the isolation and propagation of chicken PGCs three signalling pathways, AKT, MAPK and JAK/STAT, were investigated. When any of these signalling pathways were blocked, using chemical inhibitors, chicken PGC proliferation in vitro was significantly inhibited, showing the pathways to be essential for chicken PGC proliferation. Chicken PGCs were treated with individual components of the standard culture medium, FGF2, SCF, animal sera, BRL-conditioned medium, LIF and IGF, and the activation status of the key signalling pathways was assessed by western blot. Individual components of the culture medium induced activation of the AKT and MAPK pathways but not the JAK/STAT pathway. These data increase our understanding of PGC biology and are the first steps towards the development of a feeder- and serum-free medium for the growth of chicken PGCs. Published methods for the genetic manipulation of chicken PGCs are inefficient. To improve the efficiency of stable transgene integration, transposable element-derived gene transfer vectors were assessed for their ability to transpose into the genome of chicken PGCs. Comparison of Tol2 and piggyBac transposable elements, carrying reporter transgenes, demonstrated that both can be used to genetically-modify chicken cells. The incidence of stable transposition achieved was higher when using the Tol2 transposable element in comparison to the piggyBac element. The genetically-modified chicken PGCs formed functional gametes, demonstrated by injection of genetically modified chicken PGCs into host embryos which were hatched and produced transgenic offspring expressing the reporter gene construct.

All-male fry are preferred to prevent uncontrolled reproduction before harvest in intensive Nile tilapia (Oreochromis niloticus) aquaculture. Males also grow faster than females. An alternative approach to direct hormonal masculinisation of tilapia fry is to produce fry that are genetically male. However, sex determination system in tilapia is fairly complex. Recent developments have resulted in a linkage map and genetic markers that can be used to analyse the sex determination system. To analyse the genetic sex determination mechanism and to develop marker-assisted selection in the Stirling Nile tilapia population, a fully inbred line of clonal females (XX) was verified using test crosses and DNA markers (mostly microsatellites) to use as a standard reference line in sex determination studies. A series of crosses were performed involving this line of females and a range of males. Three groups of crosses were selected (each group consisted of three families) from progeny sex ratio distributions, and designated as type ‘A’ (normal XY males x clonal XX females), type ‘B’ (putative YY males x clonal XX females) and type ‘C’ (unknown groups of males x clonal XX females), for sex linkage study. For type ‘A’, inheritance of DNA markers and phenotypic sex was investigated using screened markers from tilapia linkage group 1 (LG1) to confirm the LG1-associated pattern of inheritance of phenotypic sex and the structure of LG1. Screened markers from LG1, LG3 and LG23 were used to investigate the association of markers with sex in families of type ‘B’ and ‘C’. In addition, a genome-wide scan of markers from the other 21 LGs was performed to investigate any association between markers and sex, in only families of cross type ‘B’. LG1 associated pattern of inheritance of phenotypic sex was confirmed by genotype and QTL analyses in families of cross type ‘A’. Analyses of genotypes in families of type ‘B’ and ‘C’ showed strong association with LG1 markers but no association with LG3 and LG23 markers. Genome wide scan of markers from all other LGs did not show any significant association between any markers and the sex. The allelic inheritance of two tightly linked LG1 markers (UNH995 and UNH104) in families of type ‘B’ and ‘C’ identified polymorphism in the sex determining locus: one of the alleles was associated mostly with male offspring whereas another allele was associated with both progeny (mostly males in type ‘B’ families, and approximately equal numbers in type ‘C’ families). This knowledge was used to identify and separate supermales (‘YY’ males) that should sire higher proportions of male progeny, reared to become sexually mature for use as broodstock. Two of them were crossed with XX females (one clonal and one outbred) to observe the phenotypic expression of the strongest male-associated allele in progeny sex. The observations of 98% male (99 males out of 101 progeny) and 100% male (N=75) from these two crosses respectively, suggest that a marker-assisted selection (MAS) programme for genetically male Nile tilapia production could be practical. This study also suggests that the departures from the sex ratios predicted using a “simple” XX/XY model (i.e., YY x XX should give all-male progeny) were strongly associated with the XX/XY system, due to multiple alleles, rather than being associated with loci in other LGs (e.g., LG3, LG23). This study also tentatively names the allele(s) giving intermediate sex ratios as “ambivalent” and emphasizes that the presence and actions of such allele(s) at the same sex-determining locus could explain departures from predicted sex ratios observed in some earlier studies in Nile tilapia.

Development of biomass feedstocks with desirable traits for cost-effective conversion is one of the main focus areas in biofuels research. As suggested by techno-economic analyses, the success of a lignocellulose-based biorefinery largely relies on the utilization of lignin to generate value-added products, i.e. fuels and chemicals. The fate of lignin and its structural/compositional changes during pretreatment have received increasing attention; however, the effect of genetic modification on the fractionation, depolymerization and catalytic upgrading of lignin from genetically engineered plants is not well understood. This study aims to fractionate and characterize the lignin streams from a wild-type and two genetically engineered switchgrass (Panicum virgatum) species (low lignin content with high S/G ratio and high lignin content) using three different pretreatment methods, i.e. dilute sulfuric acid, ammonia hydroxide, and aqueous ionic liquid (cholinium lysinate). The structural and compositional features and impact of lignin modification on lignin-carbohydrate complex characteristics and the deconstruction of cell-wall compounds were investigated. Moreover, a potential way to upgrade low molecular weight lignin to lipids by Rhodococcus opacus was evaluated. Results from this study provide a better understanding of how lignin engineering of switchgrass influences lignin fractionation and upgrading during conversion processes based on different pretreatment technologies.

This thesis develops biophysically-based data-driven mathematical models of intracellular calciumdynamics in ventricularmyocytes for both normal and genetically modified mouse hearts, based on species- and temperature-consistent experimental data. The models were subsequently applied to quantitatively examine the changes in calcium dynamics in mice with cardiomyocyte-specific knockout (KO) of the cardiac sarco/endoplasmic reticulum ATPase (SERCA2) gene, to determine the contributing mechanisms which underlie the ultimate development of heart failure in these animals. In Chapter 1, with emphasis on calcium dynamics and calcium regulation in heart failure, an overview of cardiac electrophysiology, excitation-contraction coupling and mathematical models of cardiac electrophysiology is provided. In Chapter 2, models of calcium dynamics in the ventricular myocytes from the C57BL/6 mouse heart at a physiological temperature is developed and validated based on species- and temperature-consistent measurements. In Chapter 3, the C57BL/6 model framework is re-parameterised to experimental data from the control and SERCA2 KO mice at 4 weeks after gene deletion. The models are then used to quantitatively characterise changes in calcium dynamics in the KO animals and the role of the compensatory mechanisms. In Chapter 4, the model framework is extended to include differential distributions of ion channels in the sarcolemma and the calcium dynamics in the sub-sarcolemmal space, with parameters in these sub-components fitted to experimentally measured calcium dynamics from the control and KO cardiomyocytes at 7-week after gene deletion. Finally in Chapter 5, conclusions are drawn, the limitations of this study are discussed, and the future extensions to this study are described.

This thesis describes the development of a framework for computational modelling of electromechanics in the mouse, with the purpose of being able to integrate cellular and tissue scale observations in the mouse and investigate physiological hypotheses. Specifically, the framework is applied to interpret electromechanical coupling mechanisms and the progression of heart failure in genetically modified mice. Chapter 1 introduces the field of computational biology and provides context for the topics to be investigated. Chapter 2 reviews the biological background and mathematical bases for electromechanical models, as well as their limitations. In Chapter 3, a set of efficient computational methods for coupled cardiac electromechanics was developed. Among these are a modified Newton method combined with a solution predictor which achieves a 98% reduction in computational time for mechanics problems. In Chapter 4, this computational framework is extended to a multiscale electromechanical model of the mouse. This electromechanical model includes our novel cardiac cellular contraction model for mice, which is able to reproduce murine contraction dynamics at body temperature and high pacing frequencies, and provides a novel explanation for the biphasic force-calcium relation seen in cardiac myocytes. Furthermore, our electromechanical model of the left ventricle of the mouse makes novel predictions on the importance of strong velocity-dependent coupling mechanisms in generating a plateau phase of ventricular pressure transients during ejection. In Chapter 5, the framework was applied to investigate the progression of heart failure in genetically modified 'Serca2 knockout' mice, which have a major disruption in mechanisms governing calcium regulation in cardiac myocytes. Our modelling framework was instrumental in showing for the first time the incompatibility between previously measured cellular calcium transients and ventricular ejection. We were then able to integrate new experimental data collected in response to these observations to show the importance of beta-adrenergic stimulation in the progression of heart failure in these knockout mice. Chapter 6 presents the conclusions and discusses possibilities for future work.

Master of Science / Department of Agricultural Economics / Timothy Dalton / Previous research in low-income countries reveals that genetically modified (GM) maize has the potential to increase yield and reduce labor use; however, other issues, especially regarding Roundup Ready (RR) maize, remain mostly unexplored. This research examines the impact of GM maize on yield, cost, and risk among 184 smallholders during the 2009-10 maize production season in two regions in KwaZulu-Natal, South Africa; Hlabisa and Simdlangetsha. Two hybrid maize varieties; Pannar and Carnia, and three GM varieties; Bt, RR, and BR (stacked with Bt and RR) are produced. In both regions, producers of RR and BR maize pay 47% more per kilogram of seed and use 44% less labor per hectare compared to other varieties. Due to low labor costs, net returns from RR and BR varieties are 25% and 40% higher than other varieties in Hlabisa and Simdlangetsha, respectively. Stochastic dominance analysis is used to compare net returns of all five varieties in both regions. RR maize is second-degree stochastic dominant to all other varieties in Simdlangetsha, while no variety is stochastically dominant in Hlabisa. Stochastic efficiency with respect to a function (SERF) analysis indicates that RR maize is the preferred variety for producers over the entire range of risk preferences in both regions. While average maize gross returns are $713 per hectare, risk premiums between $18 and $221 must be paid to RR maize producers, depending on region and farmer risk preference, to persuade them to switch to the second-most preferred variety. Econometric analysis indicates significant yield gains of at least 8% from RR maize, although the yield gain varies greatly when input endogeneity is taken into account. Elasticities of output with respect to labor are 0.41 and 0.82 for RR and non-RR maize respectively, and 0.61 and 0.33 with respect to land. A cost function analysis indicates that RR maize has 19% lower costs per maize plot, which increases to at least a 35% advantage when controlling for selectivity bias. Nonparametric kernel density estimation also reveals consistently lower total and average costs of RR maize at most levels of output, suggesting technological benefits to smallholder farmers from RR maize not available through conventionally-bred hybrids.

M. Tech. (Biotechnology, Department of Health Sciences), Vaal University of Technology / Amaranthus tricolor (A. tricolor) is a nutritious vegetable crop that is used as a subsistence and cash crop in the rural areas in Africa. Its yield and production is severely limited by abiotic stresses such as drought. Mutation technology, using gamma irradiation, was previously employed as a tool to create genetic variation in order to select for lines with improved drought-tolerance. During irradiation, 160 Gy (Gray) was selected as the optimal dosimetry that allowed subsequent seed germination. The resulting mutant lines were screened over several generations under field and greenhouse conditions and seven promising drought-tolerant lines were selected. Here we report on physiological and morphological studies of two of these Amaranthus mutant lines (#2 and #5) to confirm the enganced drought-tolerance. Plants were grown in the greenhouse in plastic pots containing germination mix with fertiliser. They were exposed to 21 days of well-watered condition, 19 days of drought-stress conditions and 7 days of re-watering. shoot height, leaf area, protein content and relative water content (RWC) of the fresh and dry material were determined colorimetrically under well-watered and drought-stress conditions, while anthocyanin was only measured during well-watered conditions. Shoot height, leaf area, number of leaves per plant and the protein content were significantly reduced under water-stress conditions. Under well-watered condition mutant #5 grew faster with the shoot length significantly higher than mutant #2 and the wild type. Even though drought adversely affected shoot lenght, mutant#5 still performed better than mutant #2 and the wild type under drought-stress conditions. While under both well-watered and drought-stress conditions, the wild type plants had bigger leaf area compared to the two mutant lines. After 16 days of drought-stress conditions, all the leaves of the wild type plants were dried out, as a result no wild type plants recovered after 8 days re-watering. Meanwhile, both mutant #2 and #5 plants recovered significantly after 8 days of re-watering. The wild type was tolerant compared to the two mutant lines. Protein content for mutant #2 plants was higher under both well-watered and drought-stress conditions but was not significantly different from mutant #5 plants compared to the wild type plants after 19 days of drought-stress conditions. Furthermore, genetic diversity was examined in all the Amaranthus lines using random amplified polymorphic DNA (RAPD) analysis. Nineteen arbitrary RAPD markers were used of which two detected polymorphisms (OPA) 07 and OPA 16).