Expression of abscisic acid using the candidate Gene NCED1 on drought stress bambara groundnut (Vigna subterranea (L.) Verdc) accessions

Abstract

Abscisic acid (ABA) functions as one of the numerous plant hormones governing a range of physiological processes in plants, including responses to water stress. In most plants, abscisic acid levels are supposedly increased under conditions of water deficit, leading to stomatal closure and reduced transpiration and ultimately a decrease in relative water content. There is little to no information related to the expressions of abscisic acid linkage to the drought tolerance usually attributed to Bambara groundnut.  The study investigated the expression of Abscisic Acid using the candidate gene 9-cis-epoxycarotenoid dioxygenase (NCED1) in seven (7) Vigna subterranea [L.] Verdc accessions under both well-watered and water stress conditions. Three healthy seeds were planted per bag, with 500 mL water administered to the plant once a day on both treatments until two weeks after flowering when the water-stressed pots received no further watering. The leaf samples were collected for RNA extraction and then differing bands intensity from amplified cDNA bands were captured for densitometric analysis using the Image J imaging software. On the other hand, data was collected on relative water content (RWC) on the individual samples. The RWC values among the accessions ranged from 82.12% to 89.24% under the well-watered condition and 62.00% to 79.43% under the water-stressed condition. The observed ABA hormone gene expression profile suggests that all the seven Bambara groundnut accessions express ABA adequately under the two water conditions identified. This indicates tolerance to water stress and the effectiveness of identifying NCED1 as a marker in drought tolerance expression studies.