Triacontanol-induced Regulation in the Key Osmoprotectants and Oxidative Defense System of Sunflower Plants at Various Growth Stages under Salt Stress

Abstract

To cite this paper: Aziz, R. and M. Shahbaz, 2015. Triacontanol-induced regulation in the key osmoprotectants and oxidative defense system of sunflower plants at various growth stages under salt stress. AbstractSalinity is one of the major environmental constraints for limiting crop production at the global level. Exogenous application of triacontanol has the ability to ameliorate the adverse effects of abiotic stresses including salinity stress by modulating a number of physio-biochemical processes in different plants. A wire house study was conducted to explore the prospective role of foliar-applied triacontanol (TRIA) in two sunflower (Helianthus annuus L.) cultivars (SMH-907 and SMH-917) at various growth stages under saline conditions. Both sunflower cultivars were grown-up in sand medium endowed with Hoagland's nutrient solution (full strength) under control (0 mM NaCl) and salt stress (150 mM NaCl) conditions. Foliar spray of three TRIA levels [0 (water spray), 50 and 100 µM] were pertained at three growth stages i.e. vegetative, flowering and vegetative + flowering stages. Imposition of salinity decreased shoot and root dry weights, while increased the accumulation of free proline, glycinebetaine (GB) and activity of glutathione reductase (GR) enzyme. However, a significant salt-induced suppression was observed in the activities of peroxidase (POD) and superoxide dismutase (SOD) enzymes. Foliar-applied TRIA improved the activities of POD, SOD and GR enzymes along with substantial increase in the free proline and glycinebetaine contents while activity of catalase (CAT) enzyme and total soluble protein contents remained unchanged under saline stress at all growth stages in both sunflower cultivars. Overall, foliar-applied TRIA was effective in ameliorating the salt-induced adverse effects on plant growth in terms of shoot and root dry weights of both sunflower cultivars particularly at vegetative growth stage by upregulating the activities of antioxidant enzymes and level of osmoprotectants.

Phenotypical and biochemical characterization of tomato plants treated with triacontanol

“…Physiological effects have been related at the biochemical level to a cellular increase in the content of photosynthetic pigments, soluble sugars, starch, phenols, and proteins 5 , and to stimulation of the activities of carbon and nitrogen metabolism enzymes, such as carbonic anhydrase 5 , 6 , nitrate reductase 6 , ribulose-1,5-bisphosphate carboxylase/oxygenase 7 , and respiratory malate dehydrogenase 8 . More recent studies documented that triacontanol improves the tolerance of plants to abiotic stresses, including salinity 9 , 10 , drought 11 , temperature 12 , and heavy metals 13 , 14 . In general, these studies demonstrated that the improvement of tolerance to stress is due primarily to the increase in the activities of antioxidant enzymes, such as superoxide dismutase, catalase, peroxidase, and those involved in the ascorbate–glutathione cycle 14 .…”