A POSSIBLE ROLE OF C4 PHOTOSYNTHETIC ENZYMES IN TOLERANCE OF TWO PAULOWNIA HYBRID LINES TO SALINITY
KATYA IVANOVA1*, TEODORA GEORGIEVA 2, YULIANA MARKOVSKA1
1 – Department of Plant Physiology, Faculty of Biology, Sofia University “St. Kliment Ohridski”, Sofia, Bulgaria
2 – Biotree LTD, Sofia, Bulgaria
* Corresponding author: ivanova.katya@abv.bg
Keywords: PEPC, NADP-MDH, NAD-MDH, malate, K/Na ratio, Paulownia lines, salinity
Abstract: The effect of salinity on the activities of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31), NADP-malate dehydrogenase (NADP-MDH, EC 1.1.1.82) and NAD-malate dehydrogenase (NAD-MDH, EC 1.1.1.37) in three years-aged Paulownia plants (P. tomentosa x fortunei - TF and P. elongata x elongata - T4) grown on two soils differing in salinity for a period of four months was investigated. The soil samples were collected from two areas of the village Belozem near the city of Plovdiv, Bulgaria. It was found that increase of the soil salinity leads to a more pronounced enhance of the activity of PEPC and malate content in the sensitive line TF at the early stages of vegetation. The activities of investigated enzymes declined significantly in T4 at the end of vegetation. The K/Na ratio in leaves of the TF line increased gradually during vegetation, while this parameter was higher in the leaves of the T4 line in the middle stage of the vegetation. Increases in the enzyme activities in both lines suggested that they might be playing a different role in their tolerance to salinity. T4 is more tolerant to salt stress than TF because it has improved growth parameters - stem length, leaf number, total dry biomass and total leaf area at the end of vegetation.