DEFENCE RESPONSES WITH TAURINE AS A NON-ESSENTIAL AMINO ACID IN WHEAT (TRITICUM AESTIVUM L.) PLANTS UNDER SALINITY CONDITIONS

Abstract

Taurine is one of the non-essential amino acids that may improve plant resistance to abiotic stresses. The role of taurine in wheat plants subjected to salt stress remains uncertain. The study evaluated the effects of foliar taurine at 0, 5, 10 and 20 µM on wheat seedlings grown under saline conditions (100 mM NaCl). Exogenous taurine significantly (P < 0.05) increased growth (shoot and root fresh weight), K, Ca, Chl a, b, Chl a + b, carotenoids, membrane stability index and antioxidant enzymes (CAT, POX, APX and SOD) under salinity stress. As well as leaf relative water content, soluble sugars and proline were significantly increased in the taurine-treated plants compared to the untreated plants under saline conditions. The molecular studies have demonstrated that taurine treated plants showed higher relative expression in HKT1 indicating the higher absorption of K. Meanwhile, there was an obvious downregulation in the genes of NHX1 and SOS1. These results imply that applied taurine can effectively decrease the uptake of Na and improve the tolerance of wheat plants to salinity stress.