Role of melatonin in leaf gas exchange by redox regulation, K+ Homeostasis and gene expression in Canola under salinity stress
Role of melatonin in leaf gas exchange by redox regulation, K+ Homeostasis and gene expression in Canola under salinity stress
- J Soil Sci Plant Nutr (Journal of Soil Science and Plant Nutrition, 25(1), 1661-1678, 2025.2025 .
Artículo
Leaf gas exchange is a key physiological trait that is highly sensitive to salinity stress. The study aimed to assess the impact of an ion signaling melatonin molecule on leaf gas exchange, K+ uptake ability and extrusion of Na+ from canola leaves. Melatonin (Mel; 1 mM) was exogenously applied as root drenching on two contrasting Brassica napus L. varieties (AARI and Faisal) under salinity stress (120 mM NaCl). Salinity stress significantly reduced plant dry matter and net photosynthesis (Pn) by lowering leaf gas exchange and increasing ROS production, and Na+ accumulation over control. However, melatonin improved leaf gas exchange, relative water contents and ultimately plant growth by regulating K+ homeostasis and antioxidant defense system in both varieties. At a mechanistic level, melatonin induced alleviation of salinity stress in canola was attributed to a set of physiological mechanisms: (i) higher activation of antioxidant defense system; (ii) better osmoregulation via higher accumulation of sugars and proline; (iii) increased expression of PM-SOS1 (Na+/H+ exchangers) leading to higher extrusion of Na+ from leaves; (iv) higher vacuolar Na+ sequestration via tonoplastic Na+/H+ antiporter; and (v) better K+ uptake ability through activation of HAK5 and HKT1 and deactivation of PM-GORK channels. Melatonin triggered first two mechanisms, which improved ROS scavenging and leaf gas exchange, while last two were important in K+ regulation in leaves. Melatonin induced salinity tolerance in canola varieties by regulating leaf gas exchange, activating ROS scavenging and maintaining Na+/K+ homeostasis via upregulation of HAK5, HKT1 and NHX genes, however, AARI outperformed than Faisal, indicating intraspecies variability in K+ regulation and redox homeostasis.
MELATONIN
NET PHOTOSYNTHETIC RATE
ROS SCAVENGING
KANTIPORTERS
Artículo
Leaf gas exchange is a key physiological trait that is highly sensitive to salinity stress. The study aimed to assess the impact of an ion signaling melatonin molecule on leaf gas exchange, K+ uptake ability and extrusion of Na+ from canola leaves. Melatonin (Mel; 1 mM) was exogenously applied as root drenching on two contrasting Brassica napus L. varieties (AARI and Faisal) under salinity stress (120 mM NaCl). Salinity stress significantly reduced plant dry matter and net photosynthesis (Pn) by lowering leaf gas exchange and increasing ROS production, and Na+ accumulation over control. However, melatonin improved leaf gas exchange, relative water contents and ultimately plant growth by regulating K+ homeostasis and antioxidant defense system in both varieties. At a mechanistic level, melatonin induced alleviation of salinity stress in canola was attributed to a set of physiological mechanisms: (i) higher activation of antioxidant defense system; (ii) better osmoregulation via higher accumulation of sugars and proline; (iii) increased expression of PM-SOS1 (Na+/H+ exchangers) leading to higher extrusion of Na+ from leaves; (iv) higher vacuolar Na+ sequestration via tonoplastic Na+/H+ antiporter; and (v) better K+ uptake ability through activation of HAK5 and HKT1 and deactivation of PM-GORK channels. Melatonin triggered first two mechanisms, which improved ROS scavenging and leaf gas exchange, while last two were important in K+ regulation in leaves. Melatonin induced salinity tolerance in canola varieties by regulating leaf gas exchange, activating ROS scavenging and maintaining Na+/K+ homeostasis via upregulation of HAK5, HKT1 and NHX genes, however, AARI outperformed than Faisal, indicating intraspecies variability in K+ regulation and redox homeostasis.
MELATONIN
NET PHOTOSYNTHETIC RATE
ROS SCAVENGING
KANTIPORTERS