Date of Award

6-2024

Document Type

Thesis

Degree Name

Master of Science in Molecular Biology and Biotechnology

Department

Biology

First Advisor

Dr. Mayank Gururani

Abstract

Auxin-repressed proteins (ARPs) are conserved in higher plants and are involved in plant growth and development by controlling gene expression. ARP1 has been studied for its role in biotic stress response, but its role in abiotic stress response remains unclear. In this study, transgenic Arabidopsis plants expressing potato (S. tuberosum) ARP1 were evaluated for their salinity stress response. By gradually increasing NaCl concentrations from 0 to 200mM, plants were subjected to high salinity stress. As compared to wild-type (WT) control plants under stressed conditions, the ARP1 transgenic plants demonstrated improved height and root length and higher chlorophyll content. Under NaCl-induced salinity stress, the stomatal conductance of ARP1 plants was higher than that of WT plants. These measures indicate stress-related tissue damage and plant water status, respectively. As compared to WT plants, ARP1 plants accumulated more proline. Genes encoding antioxidant enzymes such as, Ascorbate peroxidase (APX), Superoxide dismutase (SOD) and Catalase (CAT) were expressed at higher levels in ARP1 plants, indicating better Reactive oxygen species (ROS) detoxification capacity. Chlorophyll-a fluorescence kinetics analyses showed that overexpression of the S. tuberosum ARP1 gene increased PIABS and PItotal indices as well as quantum yields and efficiency of photosystem II (PSII) as measured in eleven critical photosynthetic parameters, on salinity stressed ARP1 plants. Overall, this study has exhibited the positive role of potato auxin-repressed protein in alleviating salinity stress tolerance in higher plants.

Arabic Abstract


اﻟﺘﻮﺻﯿﻒ اﻟﻮظﯿﻔﻲ ﻟﺠﯿﻦ اﻟﺒﻄﺎطس ARP1 اﻟﺬي ﯾﺸﻔﺮ ﺑﺮوﺗﯿﻦ اﻛﺴﻦ اﻟﻤﻜﺒﻮت ﻓﻲ ﻧﺒﺎﺗﺎت اﻻرﺑﺪوﺑﺴﯿﺲ ﺗﺤﺖ ظﺮوف إﺟﮭﺎد اﻟﻤﻠﻮﺣﺔ

ﯾﺗم ﺣﻔظ ﺑروﺗﯾﻧﺎت اﻷوﻛﺳﯾن اﻟﻣﻛﺑوﺗﺔ (ARPs) ﻓﻲ اﻟﻧﺑﺎﺗﺎت اﻟﻌﻠﯾﺎ وﺗﺷﺎرك ﻓﻲ ﻧﻣو اﻟﻧﺑﺎت وﺗطوره ﻣن ﺧﻼل اﻟﺗﺣﻛم ﻓﻲ اﻟﺗﻌﺑﯾر اﻟﺟﯾﻧﻲ. ﺗﻣت دراﺳﺔ ARP1 ﻟدوره ﻓﻲ اﻻﺳﺗﺟﺎﺑﺔ ﻟﻺﺟﮭﺎد اﻷﺣﯾﺎﺋﻲ، ﻟﻛن دوره ﻓﻲ اﻻﺳﺗﺟﺎﺑﺔ ﻟﻺﺟﮭﺎد الأﺣﯾﺎﺋﻲ ﯾظل ﻏﯾر واﺿﺣًﺎ. ﻓﻲ ھذه اﻟدراﺳﺔ، ﺗم ﺗﻘﯾﯾم ﻧﺑﺎﺗﺎت اﻷراﺑﯾدوﺑﺳﯾس اﻟﻣﻌدﻟﺔ وراﺛﯾﺎ اﻟﺗﻲ ﺗﻌﺑر ﻋن اﻟﺑطﺎطس ARP1 ﻣن ﺣﯾث اﺳﺗﺟﺎﺑﺗﮭﺎ ﻹﺟﮭﺎد اﻟﻣﻠوﺣﺔ. ﻣن ﺧﻼل زﯾﺎدة ﺗرﻛﯾزات ﻛﻠورﯾد اﻟﺻودﯾوم ﺗدرﯾﺟﯾﺎ ﻣن 0 إﻟﻰ 200 ﻣﻠم، ﺗﻌرﺿت اﻟﻧﺑﺎﺗﺎت ﻹﺟﮭﺎد ﻣﻠوﺣﺔ ﻋﺎﻟﯾﺔ. ﺑﺎﻟﻣﻘﺎرﻧﺔ ﻣﻊ ﻣﺣطﺎت اﻟﺗﺣﻛم ﻣن اﻟﻧوع اﻟﺑري (WT) ﻓﻲ ظل اﻟظروف اﻟﻣﺟﮭدة، أظﮭرت اﻟﻧﺑﺎﺗﺎت اﻟﻣﻌدﻟﺔ وراﺛﯾﺎ ARP1 ﺗﺣﺳﻧًﺎ ﻓﻲ اﻻرﺗﻔﺎع وطول اﻟﺟذر وﻣﺣﺗوى أﻋﻠﻰ ﻣن اﻟﻛﻠوروﻓﯾل. ﺗﺣت إﺟﮭﺎد اﻟﻣﻠوﺣﺔ اﻟﻧﺎﺟم ﻋن ﻛﻠورﯾد اﻟﺻودﯾوم، ﻛﺎﻧت اﻟﺗوﺻﯾﻠﯾﺔ اﻟﻔﻣﯾﺔ ﻟﻧﺑﺎﺗﺎت ARP1 أﻗل ﺑﻛﺛﯾر ﻣن ﺗﻠك اﻟﻣوﺟودة ﻓﻲ ﻧﺑﺎﺗﺎت WT. ﺗﺷﯾر ھذه اﻟﺗداﺑﯾر إﻟﻰ ﺗﻠف اﻷﻧﺳﺟﺔ اﻟﻣرﺗﺑطﺔ ﺑﺎﻹﺟﮭﺎد وﺣﺎﻟﺔ اﻟﻣﯾﺎه اﻟﻧﺑﺎﺗﯾﺔ، ﻋﻠﻰ اﻟﺗواﻟﻲ. ﺑﺎﻟﻣﻘﺎرﻧﺔ ﻣﻊ WT، ﺗراﻛﻣت ARP1 ﻛﻣﯾﺔ أﻛﺑر ﻣن اﻟﺑروﻟﯾن. ﺗم اﻟﺗﻌﺑﯾر ﻋن ﺑﯾروﻛﺳﯾداز اﻷﺳﻛورﺑﺎت (APX) ودﯾﺳﻣوﺗﺎز اﻟﻔﺎﺋﻖ أﻛﺳﯾد (SOD) واﻟﻛﺎﺗﻼز (CAT) ﺑﺷﻛل ﻣﺗﻛرر أﻛﺛر ﻓﻲ ﻧﺑﺎﺗﺎت ARP1، ﻣﻣﺎ ﯾﺷﯾر إﻟﻰ ﻗدرة أﻓﺿل ﻋﻠﻰ إزاﻟﺔ اﻟﺳﻣوم ﻣن ROS. أظﮭرت ﺗﺣﻠﯾﻼت ﺣرﻛﯾﺔ اﻟﻛﻠورو ﻓﯾل-أ أن اﻹﻓراط ﻓﻲ اﻟﺗﻌﺑﯾر ﻋن ﺟﯾن S. tuberosum ARP1 أدى إﻟﻰ زﯾﺎدة ﻣؤﺷرات أداء PIABSوPItotalﺑﺎﻹﺿﺎﻓﺔ إﻟﻰ إﻧﺗﺎﺟﯾﺔ اﻟﻛم وﻛﻔﺎءة اﻟﻧظﺎم اﻟﺿوﺋﻲ PSII ﻛﻣﺎ ﺗم ﻗﯾﺎﺳﮫ ﻓﻲ أﺣد ﻋﺷر ﻣﻌﻠﻣﺔ ﻣﮭﻣﺔ ﻟﻠﺗﻣﺛﯾل اﻟﺿوﺋﻲ، ﻋﻠﻰ ﻧﺑﺎﺗﺎت ARP1 اﻟﻣﺟﮭدة ﺑﺎﻟﻣﻠوﺣﺔ.

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