Efeito do priming com putrescina sobre aspectos bioquímicos e metabólicos durante o desenvolvimento inicial de dois híbridos de milho contrastantes para a tolerância à seca

Abstract

Plants are constantly exposed to biotic and abiotic stresses that affect their productivity, development and growth. The imbalance between the generation of reactive oxygen species and the performance of antioxidant defense systems causes oxidative stress. This study aimed to observe the action of putrescine polyamine (PUT) and its effect on oxidative stress in hybrid hybrids DKB 390 and BRS 1030 - resistant and sensitive, respectively - under water deficit condition. Analyzes of shoot and root growth, the action of the enzymes ascorbate peroxidase (APX), guaiacol peroxidase (GPX), superoxide dismutase (SOD) and catalase (CAT) were performed. The contents of amino acids, starch, total soluble sugars and reducing sugars were also evaluated. Two situations were simulated to assess the effects of this deficit: one without water limitation, whose treatments were water (control), 10 μM putrescine, 100 μM putrescine and 500 μM putrescine. And another with induction of the water deficit (-0.6 MPa) of mannitol in the solutions together with the addition of putrescine in the concentrations of putrescine 10 μM, putrescine 100 μM and putrescine 500 μM and a treatment with only water and mannitol. Both the aerial part and the roots of the DKB hybrid grew significantly more than the BRS, in all treatments. The SOD enzyme had greater activity in the roots of sensitive hybrids, mainly under higher levels of putrescine, outside the deficit condition. GPX showed greater activity on DKB roots in all treatments, compared to BRS. The two hybrids showed little change in catalase. In the roots, the DKB hybrid had greater activity in only two treatments. In the aerial part there was a difference only in BRS and none in DKB. Higher concentrations of amino acids were found both in the roots and in the aerial part of BRS with the application of putrescine under water deficit. For starch contents, differences were noted only when comparing the aerial parts between the hybrids in the absence of stress with putrescine. In relation to total soluble sugars, only the roots of BRS increased with the application of putrescine under water deficit. In reducing sugars, there was little difference in both hybrids in both shoot and roots.