Author
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Burke, John |
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Submitted to: American Journal of Plant Sciences
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/21/2017 Publication Date: 2/23/2017 Citation: Burke, J.J. 2017. Genetic diversity in the environmental conditioning of gossypium hirsutum and gossypium barbadense cultivars. American Journal of Plant Sciences. 8(3):517-532. Interpretive Summary: The present study describes a tool for evaluating the metabolic fitness of a cotton cultivar within an environment. The metabolic fitness index is a measure of the results of putting a plant through a “stress test”. The metabolic fitness indices of six cotton cultivars are shown in this paper. Cotton cultivars bred for warm environments do not cope well in cool environments, and cotton cultivars bred for cool environments do not cope well in warm environments. The data provided in this study support the usefulness of the metabolic fitness index as a tool to measure how well a plant metabolically copes in different thermal environments. Technical Abstract: Enzyme adaptations to temperature occur constantly as temperature patterns modulate diurnally and seasonally. These adaptations entail qualitative and/or quantitative metabolic changes that often provide a competitive advantage, impact migration to new environments, and effect the survival of the species. Changes in isozymes or allozymes, changes in enzyme concentration, modification by substrate and effectors, and metabolic regulation of enzyme function without changing enzyme composition are all possible strategies for adaptation to changes in temperature. The degree of adaptation among cotton cultivars to a specific thermal regime is difficult to determine from phenotypic responses of the plants. Vegetative growth responses of different cultivars may look similar, yet one cultivar may be genetically equipped to metabolize optimally within the temperature range, while a second cultivar may require multiple adaptive adjustments to maintain similar growth patterns. The present study describes a tool for evaluating the metabolic fitness of cotton cultivars within distinct thermal environments. The metabolic fitness index is a measure of the ability of leaf tissues to withstand a prolonged respiratory demand in the absence of photosynthesis. The metabolic fitness index of three Gossypium hirsutum L. cultivars and three Gossypium barbadense L. cultivars showed that the Gossypium hirsutum L. cultivars grown in a 28/20°C day/night cycle were better equipped to cope with a 16 h - 39°C treatment than the same cultivars grown in a 39/32°C day/night cycle. The Gossypium barbadense L. cultivars, on the other hand, grown in a 39/32°C day/night cycle were better equipped to cope with a 16 h - 39°C treatment than the same cultivars grown in a 28/20°C day/night cycle. The data provided in this study support the usefulness of the metabolic fitness index as a tool to measure how well a plant metabolically copes in different thermal environments. |
