Quercetin mediated salt tolerance in tomato through the enhancement of plant antioxidant defense and glyoxalase systems. - GreenMedInfo Summary

Quercetin (Qu) is a strong antioxidant among the phenolic compounds having physiological and biochemical roles in plants. Hence, we have studied the Qu evolved protection against salinity in tomato (L.). Salinity caused ionic toxicity by increasing Nacontent in seedlings along with nutritional starvation of K, Ca, and Mg. While osmotic stress was detected by higher free proline (Pro) content and lower leaf relative water content (LRWC) in salt-stressed seedlings. Salt toxicity also induced higher HOgeneration, malondialdehyde (MDA) content and lipoxygenase (LOX) activity as a sign of oxidative stress. Tomato seedlings suffered from methylglyoxal (MG) toxicity, degradation of chlorophyll, along with lower biomass accumulation and growth due to salt exposure. However, Qu application under salinity resulted in lower Na/Kdue to reduced Nacontent, higher LRWC, increased Pro, and reduction of HOand MDA content, and LOX activity, which indicated alleviation of ionic, osmotic, and oxidative stress respectively. Quercetin caused oxidative stress, lessening through the strengthening of both enzymatic and non-enzymatic antioxidants. In addition, Qu increased glutathione-transferase activity in salt-invaded seedlings, which might be stimulated reactive oxygen species (ROS) scavenging along with higher GSH content. As a result, toxic MG was detoxified in Qu supplemented salt-stressed seedlings by increasing both Gly I and Gly II activities. Moreover, Qu insisted on better plant growth and photosynthetic pigments synthesis in saline or without saline media. Therefore, exogenous applied Qu may become an important actor to minimize salt-induced toxicity in crops.