Regulation mechanism of exogenous 5-aminolevulinic acid on growth and physiological characters of ley mus chinensis (Trin.) under high temperature stress

Abstract

Modulation of growth and development under stressed conditions can be accomplished through plant growth-regulating substances. A pot study was conducted to assess morphological, physiological and biochemical changes occurring within Leymus chinensis plants in response to exogenous application of 5-aminolevulinic acid (ALA) at different concentrations (10, 50 and 100 mg L"1). Results revealed a decrease in growth, biosynthesis of photosynthetic pigments and root activity of L. chinensis plants under high temperature stress. Conversely, exogenous application of ALA proved to be an excellent remedy to ameliorate the growth and physiology of L. chinensis plants exposed to high temperature. ALA application improved plant height, leaf area, leaf length and width, plant fresh and dry weights, biosynthesis of chlorophyll a, b, total chlorophyll, carotenoids and root activity. An exacerbation was perceived in production and activity of malondialdehyde (MDA), osmolytes and enzymatic antioxidants of L. chinensis plants under high temperature. However, treatment with ALA further exalted the accumulation of proline, soluble sugars and proteins, and aggravated the activity of antioxidants viz. peroxidase, superoxide dismutase, ascorbate peroxidase, catalase and glutathione reductase while considerably lowering the production of MDA. Modulation of growth, biosynthesis of photosynthetic pigments, osmolytes and antioxidants was concentration-dependent and application of 100 mg L"1 ALA proved most advantageous. ALA has the potential to ameliorate growth and development of L. chinensis plants under high temperature stress through modulation of biosynthesis and activity of photosynthetic pigments, osmolytes and antioxidants and improve the high temperature stress tolerance.