PEP-carboxylase activity supports organic acid metabolism of maize (Zea mays) under salt stress
Previous analyses showed a significant increase in PEP-carboxylase activity in young shoots of resistant maize genotypes. Within this study several analyses were made to identify the function of an enhanced PEP-carboxylase activity during salt stress. Test plants of the resistant maize hybrid SR 03 (Zea mays) and wheat (Triticum aestivum L. cv. Thasos) were grown under two different light intensities for 20 d. In the saline treatment, NaCl was applied up to 100 mM while control plants grew under nonsaline conditions (1 mM NaCl). Analyses of fresh weight showed a comparable reduction in both genotypes and suggested salt resistance at a similar level. Analyses of sucrose concentration showed an increase in the saline treatment of both genotypes independent of the light intensity. Results of sucrose concentrations led to the deduction that an increase in PEP-carboxylase activity was not required for sugar metabolism. Independent of light intensity, alkalinity and malate concentrations were decreased only in wheat. It can be concluded that an enhancement of PEP-carboxylase activity in young shoots of maize supports organic acid metabolism under salt stress.