Biochemical response of Moringa oleifera to temperature

Moringa oleifera is a drought and heat stress tolerant tropical tree that adapts to various environmental conditions. The mechanisms allowing for this are poorly understood. One of the adaptive metabolic responses to temperature stress is the accumulation of non-structural carbohydrates, proline and phenols. The aim of this study was to determine the effect of temperature on non-structural carbohydrates, phenols and proline in leaves of M. oleifera. Moringa seedlings were grown in glasshouses having three day/night temperature regimes: 35/18, 30/15 and 25/12 degrees C. Leaf samples were collected weekly for six weeks and freeze-dried for analysis. Leaf phenols and proline were determined using a spectrophotometer, while sugars were analysed using a high performance liquid chromatograph (HPLC-RID). The results showed that temperature had a significant (P<0.05) effect on leaf proline, phenols and carbohydrates. The temperature of 35/18 degrees C increased leaf carbohydrate, proline and phenol (free and the membrane-bound phenols) concentrations, followed by 30/15 and 25/12 degrees C, respectively. Overall, proline and carbohydrate content increased with increasing temperature. The studied moringa cultivar possessed high levels of heat stress tolerance, as observed by high proline and carbohydrate content. Moringa should be promoted as a climate-smart crop in areas that are projected to experience increasing temperatures under climate change.