Abstract
Chlorophyll-a fluorescence analysis provides relevant information about the physiology of plants growing under abiotic stress. In this study, we evaluated the influence of cold stress on the photosynthetic machinery of transgenic turfgrass, Zoysia japonica, expressing oat phytochrome A (PhyA) or a hyperactive mutant phytochrome A (S599A) with post-translational phosphorylation blocked. Biochemical analysis of zoysiagrass subjected to cold stress revealed reduced levels of hydrogen peroxide, increased proline accumulation, and enhanced specific activities of antioxidant enzymes compared to those of control plants. Detailed analyses of the chlorophyll-a fluorescence data through the so-called OJIP test exhibited a marked difference in the physiological status among transgenic and control plants. Overall, these findings suggest an enhanced level of cold tolerance in S599A zoysiagrass cultivars as reflected in the biochemical and physiological analyses. Further, we propose that chlorophyll-a fluorescence analysis using OJIP test is an efficient tool in determining the physiological status of plants under cold stress conditions.
Highlights
Plants, such as turfgrasses, are constantly subjected to various abiotic stresses such as salinity, heavy metal toxicity, heat/cold, water deficit
Our results suggest that overexpression of hyperactive S599A mutant enhances cold stress tolerance in transgenic zoysiagrass, and that the JIP-test is sensitive method to evaluate the response of zoysiagrass plants under cold stress
Reduced levels of H2O2 and increased proline accumulation indicate that zoysiagrass lines overexpressing oat phytochrome A (PhyA) or S599A are more tolerant to cold temperature than the Non-transgenic zoysiagrass plants (NT) lines
Summary
Plants, such as turfgrasses, are constantly subjected to various abiotic stresses such as salinity, heavy metal toxicity, heat/cold, water deficit. The inimical effects of such abiotic stresses often lead to loss in crop yield. In order to improve the inherent stress tolerance, it is imperative to understand the effect of specific stress factors on the photosynthetic machinery of plants. Photosynthetic response of plants under abiotic stress conditions remains largely elusive as it involves complex reactions of several components occurring at various sites of the photosynthetic machinery. PLOS ONE | DOI:10.1371/journal.pone.0127200 May 26, 2015
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