Stressful saline concentrations in soils affect photosynthesis by damaging pigments, photosystems, components of electron transport system, and enzymes involved in the process. Plants respond through very complex stress adaptation mechanisms including proteome modulation, alterations in pigment content, cell osmotic adjustment and control of ion and water homeostasis mechanisms, which stabilize cytosolic glutathione redox potential, etc. The level of plant sensitivity depends on salt toxicity levels, growth stage, physiological and genetic factors. With aim the investigation of the salinity tolerant cultivars, and for the elucidation of mechanisms underlying this complex biological process, here we analyze the impact of four NaCl concentrations (0-50-100-200mM) in growth parameters (root, shoot and leaves length), pigment content (chla, chlb, carotenoids), and GSH content, during seedling of five bread wheat (Triticum aestivum L.) cultivars in modified Hoagland solutions. Based on biometric parameters, pigment synthesis and GSH content cultivar Nogal is salt-sensitive (growth and pigments reduced); cultivar Viktoria is medium-tolerant (growth partially impaired, pigments constant), cultivar Toborzo and cultivar Suba are medium-tolerant (growth partially impaired, pigments increased), cultivar Dajti salt-tolerant (growth partially impaired/ leaves developed, pigments increased). Quantity of GSH in response to different levels of salinity is cultivar specific, and time of exposure to salinity is in negative correlation to GSH content for all investigated cultivars.
Ariola Bacu, Kristjana Comashi, Markeljana Hoxhaj and Vjollca Ibro
Plants have evolved effective defense mechanisms against stress-induced oxidative damages, among which an important role play glutathione S-transferases (GSTs). This huge class of proteins have been reported to increase in a number of crops under temperature and saline stresses. However, different wheat cultivars display specific characteristics of expression. In our study we controlled the transcription of GSTF1 gene at leaves of wheat (Triticum aestivum L.) of local cultivar Dajti, evaluated previously as resistant toward salt and temperature stresses. Three different concentrations of NaCl, 50, 100, 200mM, were applied at plants germinated in Hoagland culture, and total ARN was extracted from leaves collected at 0-3-6-10-24-72 hrs after treatment. Seeds from the same cultivar were germinated in Hoagland culture under heat treatment, keeping controls at 25°C/20°C and the rest under a 35°C /25°C-day/night regime in a growth chamber. Total RNA was extracted after one week, 30, and 45 days following HT. RT-PCRs were performed using primers specific for GSTF1. Concentration of amplicons was evaluated in agarose gels. In conclusion, the transcription of GSTF1 at Dajti cultivar is reduced during the time of exposure on saline conditions, does not depend on salt concentration, and is not affected by prolonged temperature stress.