Molecular characterisation and physiological adaptations of cowpea to growth temperature

Sokolnik, Alexander and Carmo-Silva, Elizabete (2021) Molecular characterisation and physiological adaptations of cowpea to growth temperature. Masters thesis, Lancaster University.

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Abstract

This research focuses on characterising Rubisco activase expression in cowpea, as well as physiological adaptations of cowpea, Vigna unguiculata, to different temperatures. Cowpea is a drought-tolerant crop, however, increase in temperature and weather instability due to global warming can produce conditions which would stretch even cowpea tolerance to its limit. Here, physiological adaptations of cowpea to changing temperatures are characterised, and rubisco activase (Rca) expression is determined to aid in understanding temperature effects on cowpea. No previous work has been done to measure Rca expression in cowpea. Whilst some work has been done on characterising cowpea physiological responses to temperature, it has been focusing on long-term effects, and this study aims to quantify physiological adaptations during first four growth stages (until full unfolding of second trifoliate). A process for RNA extraction from cowpea leaves was optimised, a set of primers differentiating between different Rca isoforms was designed and tested, and a set of candidate reference genes was selected and tested for stability. This was used to perform qPCR to determine leaf Rca expression levels. Daily physiological observations were taken to quantify physiological adaptations. No significant difference in expression between first and second trifoliate leaves was observed for isoforms 1β, 8α, 8ββ, and 10α. There was some difference in expression for isoform 10β, but the scientific significance of this observation is hard to determine. The most expressed isoform was 1β. Isoform 8α was second most expressed followed by 8ββ, 10β and 10α. Physiologically, chlorophyll density tended to be correlated with temperature, whereas leaf size, above ground biomass, and LMA tended to be inversely correlated to growth temperature. These results could be used for further study into physiological and molecular adaptations of Cowpea to different environmental temperatures.