Browsing by Author "Klein, Ashwil"
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Item A biochemical and proteomic analysis of sugargraze sorghum under hyperosmotic stress(University of the Western Cape, 2015) Nxele, Xolisa; Ndimba, Bongani K.; Klein, AshwilSugargraze is a moderately drought tolerant sweet sorghum hybrid which is ideal for grazing, winter stand over and pit silage. A major advantage that Sugargraze has over other forages is its very high sugar content which improves feed quality thus increasing palatability and results in significantly reduced feed wastage. This study explored the influence of hyperosmotic stress on plant development, ROS accumulation, antioxidant capacity and the extent of cell death. Heat shock protein (Hsp70) expression immunoblotting assays were used to demonstrate whether the various treatment conditions induced stress within natural physiological parameters for the experimental material. This was coupled with the separation, visualization and identification of abundant proteins in Sugargraze leaves in response to hyperosmotic stress using two-dimensional gel electrophoresis (2-DE) in combination with mass spectrometry (MS). The results showed that hyperosmotic stress significantly influences plant development by reducing plant biomass and increasing the levels of ROS accumulation, proline content and subsequently reducing total chlorophyll content. An over accumulation of ROS in the form of hydrogen peroxide and lipid peroxidation was observed in the stressed plants which was supported by the extent of cell death. Although an increase in antioxidant enzyme activity (in the form of total enzymatic activity or individual isoform activity) in response to hyperosmotic stress was observed, this increase was not sufficient to counter the deleterious effects caused by the stress conditions hence the decrease in plant biomass and increase in cell death. Western blotting analysis of Sugargraze leaf tissues using Hsp70 antibodies showed that hyperosmotic stress induced Hsp70 expression to levels significantly higher than observed for the control plants. A total of thirteen CBB stained spots were selected for mass spectrometric identification, owing to their good resolution and abundance levels, and of these, nine were positively identified. Identified proteins were divided into functional categories including both known and novel/putative stress responsive proteins. Molecular and physiological functions of some of the proteins of interest identified will be subjected to further investigation via bioinformatic and molecular biology approaches.Item Biocontrol potential of fungal endophytes against Fusarium proliferatum in maize(University of the Western Cape, 2022) Fisher, Stacey; Klein, AshwilFusarium proliferatum is a fungal pathogen that is the cause of numerous diseases in various crops of fruit and vegetables. About 25% of the maize crops harvested annually are affected by mycotoxins produced by F. proliferatum which causes huge economic fatalities to the agricultural and industrial services. Fungal endophytes are naturally occurring and ever-present in various host plants. Fungal endophytes exist symbiotically with host plants; thus, they gain nutrients whilst providing benefits to the host plant. Due to the harmful effects of fungicides, an alternative eco-friendly method is required to protect crops from pathogenic fungi such as F. proliferatum, this includes the use of fungal endophytes, however, its effects have not been elucidated in literature.Item Capacity to control oxidative stress-induced caspase-like activity determines the level of tolerance to salt stress in two contrasting maize genotypes(Springer, 2013) Keyster, Marshall; Klein, Ashwil; Du Plessis, Morné; Jacobs, Alex; Kappo, Abidemi; Kocsy, Gábor; Galiba, Gábor; Ludidi, NdikoThe response of two maize (Zea mays L.) genotypes, named GR (salt-tolerant) and SK (salt-sensitive), to salt stress (150 mM NaCl) was investigated under controlled environmental growth conditions. Genotype SK experienced more oxidative damage than the GR genotype when subjected to salt stress, which corresponded to higher O2- production rate and H2O2 content in the SK genotype than the GR genotype. Induction of caspase-like activity in response to salt stress was stronger in the SK genotype than in the GR genotype. On the other hand, induction of antioxidant enzyme activity to scavenge O2- and H2O2 in response to salt stress was weaker in the SK genotype than in the GR genotype. Consequently, the higher level of oxidative damage in the SK genotype in response to salt stress was manifested as more extensive cell death and biomass reduction in the SK genotype than it was in the GR genotype. Our results suggest that a direct relationship exists between salt stress-induced oxidative damage and cell death-inducing caspase-like activity, with tolerance to the salt stress being controlled by the efficiency of the plantantioxidant enzymes in limiting salt stress-induced oxidative damage and thus limiting cell death-inducing caspase-like activity.Item Characterization of ATP-binding cassette drug transporters and their role in breast cancer treatment using in silico approach(University of the Western Cape, 2019) Hassan, Mohammed Hashim Abdalraheem; Klein, Ashwil; Pretorius, AshleyBreast cancer is the most common cancer in women worldwide, and is the second most common cancer in the world, responsible for more than 500 000 deaths annually. Estimates are that 1 in 8 women will develop breast cancer in their lifetime. In South Africa, breast cancer in women affects about 16.6 % of the population and could see a 78 % increase in cases by 2030. Comprehensive therapy on breast cancer including surgical operation, chemotherapy, radiotherapy, endocrinotherapy, etc. could help, but still has serious side effects. The Chemotherapy resistance against anticancer drugs is an emerging concern. Biomarkers have been identified as a viable option for early detection and progression of disease. Examples of biological indicators for disease could be the ATP-binding cassette (ABC) drug transporters that utilizes the energy derived from ATP hydrolysis to efflux many chemically diverse compounds across the plasma membrane, thereby playing a critical and important physiological role in protecting cells from xenobiotics. These transporters are also implicated in the development of multidrug resistance (MDR) in cancer cells that have been treated with chemotherapeutics. High expression of these membrane proteins as a family of ABC drug transporters are one of the main reasons for drug resistance by increasing the efflux rate of the anti-cancer drug from cancer cells. ABC drug transporters are considered to be one of the largest protein families in living organisms. There are 48 genes in the human genome that encode ABC transporters, which are divided into seven subfamilies (ABCA-ABCG). Studies revealed that ABC transporter genes has been shown to be associated with tumour development, progression and response to therapy, suggesting their possible use as diagnostic, prognostic and predictive biomarkers. The aim of this study was to investigate and identify novel ABC transporter genes that could be implicated in breast cancer and MDR and potentially would be a therapeutic target for successful chemotherapy treatment and disease progression and survival in breast cancer patients. An in silico approach was used to identify 10 ABC transporter genes (ABCB2, ABCB9, ABCB10, ABCC1, ABCC4, ABCC5, ABCC10, ABCC11, ABCC12, ABCD1) implicated in breast cancer by conferring drug resistance through over-expression in cancer cells. The in silico study investigated the tissue expression specificity, protein interaction/s, pathways, and comparative toxicogenomics of the identified ABC transporter genes using several computational software such as Tissue-specific Gene Expression and Regulation (TiGER), the Human Protein Atlas (HPA), Search Tool for the Retrieval of Interacting Genes/Proteins (STRING), and The Comparative Toxicogenomics Database (CTD). The 48 ABC transporter genes were shortlisted through very selective criteria that narrowed the genes down to 10. Differential expression analysis of the genes using TiGER and HPA compared expression in normal versus cancerous tissue of the candidate genes. The result showed that ABCC11 was preferentially expressed in breast tissue with an enrichment value higher than 10.0. The results also showed ABCC10 overexpressed in breast cancer tissue, making these two genes top candidates for further analysis. Result from STRING database showed a strong functional interaction network between the prioritized genes through protein homology, co-expression and text mining as evidence for the observed interactions. Furthermore, the prioritized list of genes was submitted to the CTD for intersectional analysis to obtain the toxicity relationship between the genes and the Tamoxifen as the first line chemotherapeutic treatment for breast cancer. Venn diagrams obtained from CTD showed intersectional relation between ABCB2, ABCC1, ABCC4, ABCC11, and ABCD1 genes and Tamoxifen. Furthermore, an in silico validation of the prognostic/predictive values of the 10 prioritized genes (list 2) was carried out using an online biomarker validation tool and database for cancer gene expression data using survival analysis (SurvExpress) and gene expression based survival analysis web application for multiple cancer (PROGGENE). Results obtained from the PROGGENE survival and predictive analysis showed good prognostic values for the genes ABCB2, ABCC1, ABCC4, ABCC10 and ABCC12 with their significance measured by the probability value (Pv) (0.053, 0.001118, 0.01286, 0.00604, 0.00157 respectively). From this study ABCC1, ABCC4, ABCC5, ABCC10, and ABCC11 genes could serve as putative therapeutic target biomarkers for breast cancer treatment following further in depth analysis. However, the variance in the effectiveness of individual genes suggests that the set of genes would perform better than individual gene in the management of breast cancer. The modulating roles of ABCC4, ABCC5 ABCC10, and ABCC11 in drug induced apoptosis, suggest they could probably play an important role in personalized medicine and could serve as biomarkers to monitor the prognosis and/or therapeutic outcome of chemotherapy drugs in breast cancer patients. The use of modern genomics, proteomics, bioinformatics, and systems biology approaches has resulted in a substantial increase in our ability to identify molecular mechanisms that are involved in MDR in cancer and to find drugs that may block or reverse the development of drug resistance. By using an in silico approach in this study, a list of five ABC transporter genes were identified, of which two (ABCC10 and ABCC11) could potentially serve as prognostic and predictive biomarkers for the management of breast cancer treatment.Item Comparative analysis of molecular and physiological responses of two canola genotypes to drought stress(University of the Western Cape, 2016) Nkomo, Mbukeni Andrew; Klein, Ashwil; Ludidi, Ndomelele; Ndimba, BonganiFood security has always been one of the priority concerns in Africa, and it is mostly threatened by drought stress due to climate change. Drought-induced stress is one of the serious limiting factors of plant production, and it is known to impose oxidative stress as a consequence of excessive reactive oxygen species (ROS) accumulation that lead to lipid peroxidation, which is manifested as increased cell death. Hence, this study investigated the influence of drought stress on two contrasting canola genotypes (Agamax and Garnet), by monitoring their physiological and molecular changes. The results showed that the plant growth and biomass of both genotypes were significantly affected by drought stress as a consequence of excessive ROS accumulation (manifested as H₂O₂ and OH· content). However, under drought stress conditions, the reduction in biomass and shoot length was more pronounced in the Garnet genotype when compared to that of the Agamax genotype. This was further supported by the increase in lipid peroxidation and cell death, which were shown to be significantly higher in the Garnet genotype when compared to the Agamax genotype under drought stress. ROS scavenging ability which prevents oxidative stress and ultimately ROS-induced cellular damage. Hence, given the higher levels of antioxidant activity coupled with the reduction in ROS accumulation that was observed in the Agamax genotype, we suggest that the Agamax genotype might be slightly less susceptible to drought stress, when compared to the Garnet genotype. Furthermore, understanding the proteomic responses of these two contrasting genotypes that showed a marked difference in response to drought stress might help in unlocking complex biological networks of proteins underlying drought stress tolerance. Hence we use two-dimensional (2D) gel electrophoresis coupled with Matrix assisted laser desorption/ionisation-time of flight/time of flight tandem mass spectrometry (MALDI TOFTOF MS) analysis for this part of the study, in order to detect and analyze those differentially expressed proteins or proteins whose abundance levels were influenced as a consequence of drought stress. To gain additional insight into the leaf proteomes of the two canola genotypes, a protamine sulphate precipitation (PSP) method was used to remove RuBisCo and confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis. A total of 55 well resolved protein spots were selected for mass spectrometry analysis of which 31 (56%) were positively identified using the selective criteria analysis (SCA). All positively identified proteins were then classified into functional categories including protein folding (3%), photosynthetic (29%), detoxification and protection (20%), and energy related proteins whereas 16% could not be classified into any functional category. Apart from spot 32 (Fe superoxide dismutase) and spot 34 (chloroplast beta-carbonic anhydrase), no further significant difference in protein expression/abundance was observed for all the identified proteins for both genotypes in response to drought stress. Both proteins (spots 32 and 34) have been shown to contain antioxidant activity properties which suggest that they might play a crucial role in improving drought stress tolerance in canola plants.Item Comparative venom toxin analyses of Nigerian viperidae and elapidae snakes(Elsevier, 2023) Adamude, Fatima Amin; Dingwoke, Emeka John; Klein, AshwilEnvenoming by snakebite is a serious health problem that maims and kills a large number of people, primarily in rural areas of developing African countries. The first comparative venom proteomic analyses of four snakes from the viperidae (E. ocellatus and B. arietans) and elapidae (N. haje and N. katiensis) families are presented in this study. Two-dimensional electrophoresis was combined with matrix-assisted laser desorption ionization time-of-flight mass spectrometry to analyze the venoms. Proteins were identified by comparing mass spectrometry spectra to those in the reviewed Uniprot-Serpentes database. A protein spot was considered differentially present between samples at a p-value of < 0.05 and a fold change of >2. Viper venoms contained cytotoxic-inducing proteins such as SVMPs, SVSPs, and cytotoxins, whereas elapid snake venoms contained neurotoxic proteins such as PLA2, 3-FTx, and neurotoxins.Item Development of a plum chromosome doubling method and proteomics and biochemical characterization(University of the Western Cape, 2015) Mabiya, Thembeka; Ndimba, Bongani; Mansvelt, Lucienne; Klein, AshwilChromosome doubling has become an important tool in breeding programmes as it offers the ability of introducing novel traits into existing plants. Doubled haploid plants are highly valued by both consumers and breeders as these plants usually show larger flower, leaves and fruit, thus making them more marketable. Marianna open pollinated plum rootstocks’ adaptability to different soil types and moisture conditions has been favoured in polyploidy studies as parental material in breeding programmes. The potential of the microtubule depolymerizing herbicide (oryzalin) for in vitro chromosome doubling were investigated by optimizing the concentration and incubation time of plant shoots to the antimitotic agent. Meristem tissues were treated for two time intervals (24 and 48 h) with five different concentrations of oryzalin (50, 75, 100, 150 or 200 μM) in liquid Murashige and Skoog (MS) medium. After treatment, plants were allowed to grow under a 16/8 h light/dark photoperiod at 24±2˚C for 4 weeks. One and two-dimensional gel electrophoresis (2-DE) coupled with mass spectrometry (MS) was used to separate, visualise and identify differently expressed proteins. Furthermore, changes in ROS accumulation, photosynthetic pigmentation, lipid peroxidation and antioxidant enzyme activity (SOD, APX and GR) were investigated. Flow cytometry results revealed that treatment of plants with oryzalin concentrations ranging from 75 to 150 μM induced ploidy after 24 h exposure whereas, 200 μM produced mixoploids containing both tetraploid and octoploids plants after 24 h exposure. Longer incubations of 48 h were detrimental to plant tissues as complete mortality was observed in the higher concentration (100 to 200 μM) treatments. Mass spectrometry analysis identified 14 differentially expressed protein spots that were characterized into different functional categories. ROS accumulation, the extent of lipid peroxidation and antioxidant capacity were differentially regulated in response to oryzalin treatment whereas photosynthetic pigments were significantly enhanced. The results suggests that oryzalin-induced proteins may act as potential biomarkers to improve fruit characteristics in future breeding programs whereas antioxidant enzymes play an important role in scavenging ROS in plants to enhance their adaptability to different environmental conditions.Item Development of Effective Therapeutic Molecule from Natural Sources against Coronavirus Protease(MDPI, 2021) Fadaka, Adewale Oluwaseun; Sibuyi, Nicole Remaliah Samantha; Martin, Darius Riziki; Klein, AshwilAbstract: The SARS-CoV-2 main protease (Mpro) is one of the molecular targets for drug design. Effective vaccines have been identified as a long-term solution but the rate at which they are being administered is slow in several countries, and mutations of SARS-CoV-2 could render them less effective. Moreover, remdesivir seems to work only with some types of COVID-19 patients. Hence, the continuous investigation of new treatments for this disease is pivotal. This study investigated the inhibitory role of natural products against SARS-CoV-2 Mpro as repurposable agents in the treatment of coronavirus disease 2019 (COVID-19). Through in silico approach, selected flavonoids were docked into the active site of Mpro. The free energies of the ligands complexed with Mpro were computationally estimated using the molecular mechanics-generalized Born surface area (MM/GBSA) method. In addition, the inhibition process of SARS-CoV-2 Mpro with these ligands was simulated at 100 ns in order to uncover the dynamic behavior and complex stability. The docking results showed that the selected flavonoids exhibited good poses in the binding domain of Mpro. The amino acid residues involved in the binding of the selected ligands correlated well with the residues involved with the mechanism-based inhibitor (N3) and the docking score of Quercetin-3-O- Neohesperidoside (−16.8 Kcal/mol) ranked efficiently with this inhibitor (−16.5 Kcal/mol). In addition, single-structure MM/GBSA rescoring method showed that Quercetin-3-O-Neohesperidoside (−87.60 Kcal/mol) is more energetically favored than N3 (−80.88 Kcal/mol) and other ligands (Myricetin 3-Rutinoside (−87.50 Kcal/mol), Quercetin 3-Rhamnoside (−80.17 Kcal/mol), Rutin (−58.98 Kcal/mol), and Myricitrin (−49.22 Kcal/mol). The molecular dynamics simulation (MDs) pinpointed the stability of these complexes over the course of 100 ns with reduced RMSD and RMSF. Based on the docking results and energy calculation, together with the RMSD of 1.98 ± 0.19 Å and RMSF of 1.00 ± 0.51 Å, Quercetin-3-O-Neohesperidoside is a better inhibitor of Mpro compared to N3 and other selected ligands and can be repurposed as a drug candidate for the treatment of COVID-19. In addition, this study demonstrated that in silico docking, free energy calculations, and MDs, respectively, are applicable to estimating the interaction, energetics, and dynamic behavior of molecular targets by natural products and can be used to direct the development of novel target function modulators.Item Diagnostic approaches of pneumonia for commercial-scale biomedical applications: An overview(Taylor & Francis, 2020) Bakare, Olalekan Olanrewaju; Fadaka, Adewale Oluwaseun; Klein, AshwilPneumonia remains the leading infectious cause of death among children under five years of age, and the elderly. Several biomarkers, which have been identified for its diagnosis lack specificity, as they could not differentiate viral from bacterial pathogens of the disease; these biomarkers also fail to establish a distinction between pneumonia and other associated diseases such as pulmonary tuberculosis and Human Immunodeficiency Virus (HIV). This review outlined the menace of pneumonia disease from the statistical prevalence, clinical and immunological view, challenges with the methods used in diagnosis, and more useful information about methods of diagnosis of pneumonia with their limitations as well. Additionally, the use of aptamers and antimicrobial peptides (AMPs) rather than antibodies to bind and recognize receptors for diagnostics, offers several advantages over other biomarkers shortcomings such as non-specificity.Item Dietary effects of antimicrobial peptides in therapeutics(Taylor & Francis, 2020-02-17) Bakare, Olalekan Olanrewaju; Fadaka, Adewale Oluwaseun; Klein, Ashwil; Pretorius, AshleyThe notable increase in drug-resistant infections and the failure of the most potent antibiotics to establish their curative effect without side effect have presented a serious need for the discovery of new therapeutic agent and the study of dietary implications on the mode of entry of these therapeutic agents in the human system. This review provides insight into the forms and modes of action, and roles of beneficial but limited and underutilized antimicrobial peptides for use in dietary formulations, with particular focus on the technologies employed for their discovery as well as their dietary efficacy. The wide spectrum of activities of these peptides will allow the opportunity to explore their benefits as dietary supplements and additives.Item Drought and salinity stress alters ROS accumulation, water retention, and osmolyte content in sorghum plants(Elsevier, 2017) Nxele, Xolisa; Klein, Ashwil; Ndimba, Bongani Kaiserbiotic stresses such as drought and salinity are major environmental factors that influence crop productivity worldwide. These adverse conditions induce osmotic stresses in plant cells by decreasing water availability, thus leading to loss of cell turgor and the accumulation of reactive oxygen species (ROS) that are detrimental to plant growth and development. To survive such harsh environmental conditions, plants must initiate intracel- lular and physiological signaling networks to rapidly respond and efficiently neutralize these stresses. Inefficient scavenging of ROS would lead to increased levels of cell death, thus inhibiting plant growth and reducing crop productivity. This study investigates the effect of drought and salinity stress on plant growth, water retention, oxidative damage, chlorophyll content, and proline accumulation in sorghum plants. Plant growth, biomass, and leaf chlorophyll were significantly reduced whereas the total proline content was enhanced in response to stress conditions. The significant increase in hydrogen peroxide content as a consequence of stress conditions resulted in augmented levels of lipid peroxidation, which was manifested as extensive cell death and biomass reduction.Item Effect of Fusarium oxysporum on the physiological and molecular responses of cowpea plants(The University of the Western Cape, 2017) Badiwe, Mihlali; Klein, Ashwil; Rafudeen,SuhailCowpea is a tropical, drought-tolerant legume crop that is indigenous to Africa. The crop is of nutritional importance to both animals and humans as part of their diet. Stress to crop plants is defined as any factor that negatively influences the growth and reproduction of a plant below the capabilities of the genotype.Item The effects of gallic acid on the membrane proteome and antioxidant system of wheat plants under salt stress(University of Western Cape, 2020) Mohamed, Gadija; Klein, AshwilSalt stress is a major abiotic stress that accounts for huge agricultural losses worldwide, which in turn threaten food security and sustainable agriculture. Salt triggers the excessive production of reactive oxygen species (ROS) which accumulate to levels that become toxic to plants, resulting in cell death and reduced plant growth. Part of the plant’s mechanisms to counteract ROS-induced cell death involves the scavenging ability of the antioxidant defense system to maintain redox homeostasis. Gallic acid (GA) is an antioxidant that has been shown to reduce salt-induced ROS in legume plants. However, its effects on wheat plants have not been elucidated. This study thus investigated the role of exogenous GA (250 μM) on the physiological responses and antioxidant system of wheat plants under salt stress (150 mM). In addition, this study also investigated how GA and salt stress influenced changes in the membrane proteome of wheat plants using LC-MS proteomic analysis.Item Enzymatic and proteomic exploration into the inhibitory activities of lemongrass and lemon essential oils against Botrytis cinerea (causative pathogen of gray mold)(Frontiers Media, 2023) Kgang, Itumeleng E.; Klein, Ashwil; Mohamed, Gadija G.Essential oils (EOs) have been demonstrated as efficacious against B. cinerea. However, the underpinning enzymatic and proteomic mechanism for these inhibitory effects is not entirely clear. Thus, this study examined the effects of lemon (Le) and lemongrass (Lg) EOs (individually and in combination) against B. cinerea based on enzymatic and proteomic analyses. Proteomics data are available via ProteomeXchange with identifier PXD038894. Both EOs (individually and in combination) displayed abilities to induce scavenging as observed with the reduction of H2O2. Measured malondialdehyde (MDA) and superoxide dismutase (SOD) activity were increased in all EOs treated B. cinerea mycelia compared to the control. Ascorbate peroxidase (APX) activity was highest in Lg treated B. cinerea (206% increase), followed by combined (Le + Lg) treatment with 73% compared to the untreated control.Item Enzymatic and proteomic exploration into the inhibitory activities of lemongrass and lemon essential oils against botrytis cinerea (causative pathogen of gray mold)(Front. Microbiol, 2023) Klein, Ashwil; Kgang, Itumeleng Eugenia; Mohamed, Gadija G.; Mathabe, Patricia M. K.; Belay, Zinash A; Caleb, Oluwafemi JamesIntroduction: Essential oils (EOs) have been demonstrated as efficacious against B. cinerea. However, the underpinning enzymatic and proteomic mechanism for these inhibitory effects is not entirely clear. Methods: Thus, this study examined the effects of lemon (Le) and lemongrass (Lg) EOs (individually and in combination) against B. cinerea based on enzymatic and proteomic analyses. Proteomics data are available via ProteomeXchange with identifier PXD038894. Results and discussion: Both EOs (individually and in combination) displayed abilities to induce scavenging as observed with the reduction of H2O2. Measured malondialdehyde (MDA) and superoxide dismutase (SOD) activity were increased in all EOs treated B. cinerea mycelia compared to the control. Ascorbate peroxidase (APX) activity was highest in Lg treated B. cinerea (206% increase), followed by combined (Le + Lg) treatment with 73% compared to the untreated control. Based on GC-MS analysis, the number of volatile compounds identified in lemon and lemongrass EOs were 7 and 10, respectively. Major chemical constituent of lemon EO was d-limonene (71%), while lemongrass EO was a-citral (50.1%). Based on the interrogated LC-MS data, 42 distinct proteins were identified, and 13 of these proteins were unique with 1, 8, and 4 found in Le-, Lg-, and (Le + Lg) EOs treated B. cinerea, respectively, and none in control. Overall, 72% of identified proteins were localized within cellular anatomical entity, and 28% in protein-complexes. Proteins involved in translation initiation, antioxidant activity, protein macromolecule adaptor activity and microtubule motor activity were only identified in the Lg and (Le + Lg) EOs treated B. cinerea mycelia, which was consistent with their APX activities.Item Exogenous caffeic acid alters molecular responses in Salvia hispanica L.(University of the Western Cape, 2016) Jones, Shelby Ann; Klein, AshwilSalt stress is one of the most important abiotic stresses, resulting in the accumulation of ROS, which amount to great agricultural losses by influencing plant yield and in turn threaten sustainable agriculture and food security worldwide. ROS accumulates to levels that can become toxic to plants and is dependent on the scavenging ability of the antioxidant system to maintain redox homeostasis. Caffeic acid (CA) is a known antioxidant that have been shown to reduce the formation/production of ROS in legume plants exposed to salt stress. However, its' effect on pseudocereal plants such as chia have not been elucidated. This study investigated the influence of exogenous caffeic acid (at a final concentration of 100 ?M) on the physiological and biochemical responses of chia plants under salt stress (100 mM). Furthermore, this study also investigated how caffeic acid and salt stress influenced protein changes in chia leaves using gel based proteomic analysis coupled with mass spectrometry.Item Exogenous p-coumaric acid improves salvia hispanica l. Seedling shoot growth(MDPI Open Access Journals, 2019) Nkomo, Mbukeni; Gokul, Arun; Keyster, Marshall; Klein, Ashwilp-Coumaric acid (p-CA) belongs to a family of natural esters of hydroxycinnamic acid compounds that have been shown to modulate plant growth and metabolism. In this study, we investigated the effect of exogenous p-CA on plant growth, reactive oxygen species (ROS)-induced oxidative damage, photosynthetic metabolism, osmolyte content and changes in superoxide dismutase (SOD) enzymatic activity.Item Functional prediction of candidate micrornas for CRC management using in silico approach(MDPI, 2019) Fadaka, Adewale Oluwaseun; Pretorius, Ashley; Klein, AshwilApproximately 30–50% of malignant growths can be prevented by avoiding risk factors and implementing evidence-based strategies. Colorectal cancer (CRC) accounted for the second most common cancer and the third most common cause of cancer death worldwide. This cancer subtype can be reduced by early detection and patients’ management. In this study, the functional roles of the identified microRNAs were determined using an in silico pipeline. Five microRNAs identified using an in silico approach alongside their seven target genes from our previous study were used as datasets in this study. Furthermore, the secondary structure and the thermodynamic energies of the microRNAs were revealed by Mfold algorithm. The triplex binding ability of the oligonucleotide with the target promoters were analyzed by Trident. Finally, evolutionary stage-specific somatic events and co-expression analysis of the target genes in CRC were analyzed by SEECancer and GeneMANIA plugin in Cytoscape. Four of the five microRNAs have the potential to form more than one secondary structure. The ranges of the observed/expected ratio of CpG dinucleotides of these genes range from 0.60 to 1.22.Item Gallic acid modulates salt stress tolerance in soybean plants by regulating antioxidant capacity(University of the Western Cape, 2017) Menzi, Pateka; Klein, Ashwil; Keyster, MarshallSoybean [Glycine max L (mer)] is one of the top commodity crops in the world including South Africa (de Beer and Prinsloo, 2013). These small yet important podded legumes are a great source of protein and are used in many forms.Item Heavy metal stress and mitogen activated kinase transcription factors in plants: Exploring heavy metal-ros influences on plant signalling pathways(John Wiley and Sons Inc, 2024) Niekerk, Lee-Ann; Basson, Gerhard; Klein, Ashwil; Keyster, MarshallDue to their stationary nature, plants are exposed to a diverse range of biotic and abiotic stresses, of which heavy metal (HM) stress poses one of the most detrimental abiotic stresses, targeting diverse plant processes. HMs instigate the overproduction of reactive oxygen species (ROS), and to mitigate the adverse effects of ROS, plants induce multiple defence mechanisms. Besides the negative implications of overproduction of ROS, these molecules play a multitude of signalling roles in plants, acting as a central player in the complex signalling network of cells. One of the ROS-associated signalling mechanisms is the mitogen-activated protein kinase (MAPK) cascade, a signalling pathway which transduces extracellular stimuli into intracellular responses. Plant MAPKs have been implicated in signalling involved in stress response, phytohormone regulation, and cell cycle cues. However, the influence of various HMs on MAPK activation has not been well documented. In this review, we address and summarise several aspects related to various HM-induced ROS signalling. Additionally, we touch on how these signals activate the MAPK cascade and the downstream transcription factors that influence plant responses to HMs. Moreover, we propose a workflow that could characterise genes associated with MAPKs and their roles during plant HM stress responses.