A study on photochemical activity stability of chloroplast and its relationship with antioxidative enzymes from selected plant leaves

Yeoh, Loo Yew (2019) A study on photochemical activity stability of chloroplast and its relationship with antioxidative enzymes from selected plant leaves. Master dissertation/thesis, UTAR.

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Abstract

Chloroplasts are organelles involved in oxygenic photosynthesis and biosynthesis of important nutrients. The electron transport properties of isolated chloroplasts are being utilized to build biofuel cells or biosensors. To understand the plant chloroplast photochemical activity stability, this study evaluated the functionality parameters of isolated chloroplasts, stability of photochemical activity of the isolated and stored chloroplast, response of indigenous plant leaf towards water and salinity stress and also relationship of the leave’s anti-oxidative enzymes and photochemical activity and stability of chloroplast of four plant samples, namely Amaranthus tricolor Linn., Pandanus amaryllifolius, Elaeis guineensis and Pistia stratiotes. The chloroplast was isolated followed by the determination of chlorophyll content, microscopic examination and storage. A. tricolor Linn. exhibited highest chlorophyll content, E. guineensis exhibited highest Hill reaction activity (HRA) and greatest storage stability. Rapid freezing with liquid nitrogen and stored at -20oC was proven to better preserve the isolated chloroplast than only stored at 4oC without pre-freezing. In the study of plant leaf, moisture content and electrolyte leakage were determined and salt tolerance of plant leaf was studied. E guineensis and P. amaryllifolius exhibited higher tolerance towards salinity stress due to high proportion of lignified tissues, thick cuticle and low moisture content. For the extraction of crude enzyme, the protein content was determined followed by the qualitative study of anti-oxidative enzyme activity: ascorbate peroxidase (APX), catalase (CAT), peroxidase (POX), guaiacol peroxidase (GPX), pyrogallol oxidase (PO), catechol oxidase (CO), and superoxide dismutase (SOD). E. guineensis exhibited highest APX, POX and CO activity; P. stratiotes exhibited highest CAT, GPX and PO activity; while P. amaryllifolius exhibited highest SOD activity. Correlation analysis suggested that APX, CAT, PO, and CO can probably be used as a biomarker for chloroplast photochemical activity; while CAT, GPX, and PO may be used as a biomarker for isolated chloroplast photochemical stability at prolonged storage.

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