Exogenous application of L-methionine mitigates the drought-induced oddities in biochemical and anatomical responses of bitter gourd (Momordica charantia L.)

Abstract

Methionine is an important sulfur-containing amino acid and it plays a central role for several diverse purposes in the living organisms. This study was arranged to determine the effect of foliage application of 10 and 20 mg/L of L-methionine to analyze various physio-biochemical attributes and different anatomical features of bitter gourd (Momordica charantia L.) under control and drought stress conditions. Water deficit conditions (60 % field capacity) adversely reduced shoot fresh and dry weights, root fresh weight, shoot length, leaf xylem area, leaf phloem area, petiole adaxial epidermis thickness, petiole xylem area, petiole phloem area, and petiole cortical cell area. While a considerable elevation was found in total phenolics, glycine betaine, leaf adaxial and abaxial epidermal thickness, leaf vascular bundle area, petiole adaxial epidermal cell area and petiole vascular bundle area. The foliar application of L-methionine increased the shoot and root fresh weights, shoot length, total phenolics, ascorbic acid, glycine betaine, leaf abaxial epidermal thickness, leaf adaxial epidermal cell area, leaf abaxial epidermal cell area, leaf vascular bundle area, leaf xylem area and leaf phloem area. The application of 10 mg/L L-methionine was found to be comparatively more effective for regulating the levels of hydrogen peroxide, leaf abaxial epidermal thickness, leaf abaxial epidermal cell area, leaf xylem area, petiole abaxial epidermal thickness, whereas 20 mg/L concentration was effective for improving shoot fresh weight, shoot dry weight, shoot and root lengths, chlorophyll a and glycine betaine contents. Overall, bitter gourd cultivar Ruyu-53 was relatively better in proline, total phenolics and petiole abaxial epidermis thickness, whereas cv. Ruyu-146 was better in accumulating ascorbic acid.