Monitoring the levels of phi and tau group GST genes in wheat cultivars under osmotic stress

GST isoenzymes represent a large and variable group of antioxidative enzymes, with several different activities and sequence patterns. The GST activities of the isohydric drought-tolerant Triticum aestivum L. cv. Kobomugi and the anisohydric cv. Öthalom were measured after one week of 400 mOsm polyethylene glycol (PEG) treatment. The GST activities were much higher in the roots than in the shoots and were induced by PEG especially in the roots. The aim of our work was to sort out the osmotic stress related wheat GST genes. The changes in enzyme activities and expression of several GST-coding sequences were in good correlation. Both cultivars responded to osmotic stress. Higher induction, especially in phi class GSTs was detectable in the isohydric Kobomugi cultivar. Elevations were measured in the ranscript amounts of six different GST genes

Changes in water and chlorophyll fluorescence parameters under osmotic stress in wheat cultivars

Drought tolerant wheat cultivars exposed to low water potential can be characterized by growth response, stomatal conductance of leaves, by changes in water relations and ion accumulation of tissues and by fluorescence induction parameters under water stress. Two strategies of acclimation to drought stress have been found: plants using the first strategy save tissue water content by a fast decrease of stomatal conductance, maintain pressure potential and photosynthetic activity of leaves. In the second group the closure of stomata occurs later resulting in an intensive loss of water and a fast decrease of water potential in the leaves and tissues restore their turgor after a relatively long acclimation phase

Induction and regulation of glutathione transferases in wheat species exposed to PEG induced osmotic stress

The large and variable family of glutathione transferases (GST) has several functions in the stress response mechanisms. Our aim was to define the roles of different GST types in defence during osmotic stress conditions in wheat seedlings and to characterise their regulation by the stress hormone abscisic acid (ABA). Two wheat cultivars with different drought tolerance ability were exposed to 400 mOsm polyethylene glycol induced osmotic stress for one week. The hyperosmolarity of the nutrient solution increased the GST activity and the transcript amount of the selected tau group GSTs in the drought tolerant Kobomugi and moderately drought tolerant GK Öthalom cultivars. The role of abscisic acid in the regulation of GST expression was examined by the inhibition of ABA biosynthesis pathway with fluridone. The tau group GST expression of the two cultivars responded differently to the ABA biosynthesis inhibition

Changes of glutathione S-transferase activities and gene expression in Triticum aestivum during polyethylene-glycol induced osmotic stress

Glutathione S-transferase (GST) isoenzymes represent a large and variable group of antioxidative enzymes, with several different activities and sequence patterns. The GST activities of drought-tolerant Triticum aestivum L. cv. Kobomugi and cv. Plainsman were measured after one week 400 mOsm polyethylene glycol (PEG) treatment. The GST activities were much higher in the root than in the shoot and were induced by PEG especially in root. The aim of our work was to sort out the drought stress related wheat GST genes. Phylogenetic analysis of wheat GSTs was performed in silico and using the tentative consensus sequences a dendogram was composed. According to the conserved sequences used for classification of GST proteins, we could identify six groups of wheat GSTs. The phi GSTs are the most heterologous group, containing 25 sequences. The zeta, theta and tau GSTs are represented by 10, 9 and 8 TCs respectively. There are two other unidentified groups containing 8 and 6 sequences. Homology found between the osmotic stress upregulated sequences and the GST coding TCs were identified

A növényi méregtelenítéssel (glutation transzferázokkal) kapcsolatos kutatások a Szegedi Tudományegyetem Növénybiológiai Tanszéken

A növényeknek a sikeres élet szempontjából alapvetően fontos a hatékony méregtelenítés, emiatt kifejlesztettek egy hatékony rendszert a mérgező vegyületek átalakítására, eltávolítására. Ennek a rendszernek a részei glutation transzferáz fehérjék csoportjai, mely enzimek képesek összekapcsolni a növényi sejtre mérgező anyagot valamilyen más molekulával, így kevéssé mérgező terméket létrehozva. A Szegedi Tudományegyetem Növénybiológiai Tanszékén részletes kutatások folynak az enzimcsalád szerepének felderítésére. A kutatások eleinte búza (Triticum aestivum) növények felhasználásával zajlottak (2000-es évek elejétől), majd a vizsgálati növények köre később kibővült indiai mustárral, nyárfával, paradicsommal, lúdfűvel, szálkaperjével és pipaccsal is (Brassica juncea, Glycine max, Populus alba, Solanum lycopersicum, Arabidopsis thaliana, Brachypodium distachyon, Ambrosia artemisiifolia, Papaver rhoeas). Jelenleg az SZTE TTIK BI Növénybiológiai Tanszékén már két csoport foglalkozik a glutation transzferáz enzimek pontos szerepének és szabályozásának azonosításával: a Növényi Molekuláris Biológia Csoport (2000-es évek elejétől folyamatosan), és a Növényi Stresszfiziológiai és Fotoszintézis Kutatócsoport (2017-től). Remélhetőleg, ez a lassan húsz éve tartó kutatási téma fennmarad, és eredményei továbbra is szerves részét képezheti a nemzetközi irodalomnak

Nocturnal Red Light Application Modulated the Fumonisin B1-Induced Changes in Glutathione Transferases of Different Wheat Cultivars

Plant defense responses against Fusarium infection can be controlled by light. In this study, the effects of nocturnal red light were investigated on glutathione transferases (GSTs) in the leaves of the moderate- and high- Fusarium resistant wheat cultivars, GK Ígéret and GK Arató, respectively. GST activity increased in the light phase during the day, while it decreased after midnight. Since GST activity was lowest at midnight, we examined whether red light application at midnight could prevent the night-time drop in enzyme activity. We found that 15-min-long nocturnal red light application was effective to increase GST activity at dawn. The effects of red light pretreatments on GST expression and activity, as well as the oxidative stress induced by fumonisin B1 (FB1), were investigated. FB1 exposure increased GST activity and the expression of GST genes at dawn but nocturnal red light application in combination with the mycotoxin also increased GST activity and the transcript levels of the selected GST s in the resistant GK Arató. In addition to its effects on GSTs, it was discovered that, depending on the degree of tolerance, nocturnal red light increased the activity of the major antioxidant enzymes at dawn in both of the chosen wheat genotypes. These decreased FB1’s oxidative stress-causing actions, resulting in lower lipid peroxidation and less cell viability loss when exposed to the mycotoxin. Pretreatment with nocturnal red light enhanced the activity of GST and antioxidant enzymes in wheat plant leaves, contributing to FB1 detoxification and reducing oxidative stress