Browsing by Author "Ali, Ali Elnaeim Elbasheir"

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    Comparative molecular, physiological and proteomic analyses of maize and sorghum subjected to water deficit stress
    (University of the Western Cape, 2019) Ali, Ali Elnaeim Elbasheir; Ludidi, Ndiko; Husselmann, Lizex; Tabb, David
    Drought is a major abiotic stress which causes not only differences between the mean yield and the potential yield but also yield variation from year to year. Although selection for genotypes with improved productivity under drought environments has been a central goal of numerous plant breeding programs, the molecular basis for plant tolerance towards drought stress is still poorly understood. Exposure of plants to this abiotic stress is known to trigger excessive formation of reactive oxygen species (ROS), which induce cell death and reduce growth. Part of the mechanism of plant responses to drought involves alterations in the expression of antioxidant enzymes and biosynthesis of different compatible solutes such as proline. Sorghum is regarded as generally more drought tolerant than maize, and it is a potential key model system for investigating the physiological and molecular mechanisms conferring drought tolerance. Comparative studies in crop plants to decipher differences in drought tolerance are essential for crop improvement to sustain a higher level of production, which in turn will improve food security, under severe drought conditions resulting from climate change. On this basis, the aim of this study is to determine molecular differences between Zea mays and Sorghum bicolor in response to drought stress in an attempt to identify novel biomarkers for drought tolerance. The physiological and molecular responses of maize and sorghum were studied for changes in growth, chlorophyll content, relative water content, ROS content, lipid peroxidation level, proline content, and antioxidant enzyme activity. Spectral Count Label-free Quantitation analysis was conducted to reveal the changes in protein profiles under drought in attempt to identify drought-responsive molecular mechanisms in the leaves of the two plant species. In this study, water deficit triggered mechanisms that resulted in overproduction of ROS in both Zea mays and Sorghum bicolor. However, Sorghum bicolor showed less oxidative damage under water stress compared to Zea mays. Drought-induced proline accumulation in the roots of Sorghum bicolor was associated with enhanced water retention. Significant changes were identified in the antioxidant enzyme activity between the two plant species in response to drought conditions. Proteomics results showed differing patterns for drought-responsive proteins in the two species. Together with the physiological, biochemical and proteomic profiling results between Zea mays and Sorghum bicolor, potential proteins and/or metabolic pathways underlying drought tolerance were identified. The findings obtained through this study provide insight towards understanding the molecular basis of crop drought tolerance.
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    Comparative proteomics analysis between maize and sorghum uncovers important proteins and metabolic pathways mediating drought tolerance
    (MDPI, 2023) Ali, Ali Elnaeim Elbasheir; Husselmann, Lizex Hollenbach; Tabb, David L.
    Drought severely affects crop yield and yield stability. Maize and sorghum are major crops in Africa and globally, and both are negatively impacted by drought. However, sorghum has a better ability to withstand drought than maize. Consequently, this study identifies differences between maize and sorghum grown in water deficit conditions, and identifies proteins associated with drought tolerance in these plant species. Leaf relative water content and proline content were measured, and label-free proteomics analysis was carried out to identify differences in protein expression in the two species in response to water deficit. Water deficit enhanced the proline accumulation in sorghum roots to a higher degree than in maize, and this higher accumulation was associated with enhanced water retention in sorghum. Proteomic analyses identified proteins with differing expression patterns between the two species, revealing key metabolic pathways that explain the better drought tolerance of sorghum than maize.
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    Deciphering the determinants of molecular physiological responses to drought and heat stress in sorghum lines contrasting in stress tolerance via a proteomics approach
    (University of the Western Cape, 2022) Ali, Ali Elnaeim Elbasheir; Ludidi, Ndiko
    Sorghum is an important crop in Sub-Saharan Africa and South Asia. The predicted rise in global temperatures will increase the probability of exposing sorghum to heat waves in combination with drought. Thus, production and availability of sorghum and its products will be negatively affected. Although much progress has been made in identifying molecular processes involved in some crop responses to drought or heat stress, knowledge on such responses in sorghum is limited and in fact does not exist for combined drought and heat stress in sorghum lines that respond differently to these stresses.