Changes in activities of antioxidant enzymes and photosynthetic attributes in triticale (×Triticosecale Wittmack) genotypes in response to long-term salt stress at two distinct growth stages

Abstract

To examine the impact of long-term salinity on triticale, two salt-tolerant (ET-84-15 and ET-86-9) and two salt-sensitive (ET-85-17 and Jouvanilo) genotypes were grown in a sand culture containing Hoagland solution with 200 mM NaCl. Lipid peroxidation (LPO), hydrogen peroxide (H2O2), photosynthetic parameters, and antioxidant enzymes including catalase (CAT), guaiacol peroxidase (GPOD), superoxide dismutase (SOD), and ascorbate peroxidase (APX) were analyzed at the late tillering (LT) and flowering (FL) stages. A substantial reduction was found in the net photosynthetic rate, stomatal conductance, and transpiration rate of the triticale genotypes due to salt stress, with a more noticeable decline in the sensitive ones. Salt-treated plants indicated the presence of high amounts of H2O2 and LPO with a subsequent increase in the activities of the enzymes’ SOD, CAT, and GPOD in comparison with the control treatment. Conversely, APX activities remained unaltered or decreased slightly by salt stress. The salt-tolerant genotypes exhibited lower H2O2 and LPO, and displayed increased activities of the enzymes participating in the reactive oxygen scavenging system except for APX. The activities of the antioxidant enzymes under both the saline and non-saline conditions were found to be higher at the FL stage than at the LT one. This may explain partly the reason for why triticale is more tolerant at the FL stage. These results clearly demonstrate that the activation of SOD, CAT, and GPOD could contribute to the salt-stress tolerance in triticale.