Regulation of free amino acid and polyamine levels during cold acclimation in wheat

The effect of cold acclimation on free amino acids and polyamines was compared at metabolite and transcript level in wheat chromosome 5A substitution lines with different freezing tolerance. Three weeks at 2°C resulted in increased H2O2 content which alteration may affect the metabolism of these compounds. The concentration of most free amino acids gradually increased during the treatment. The expression of the genes encoding enzymes of amino acid metabolism, thus that of pyrroline-5-carboxylate reductase, glutamate synthetase and aspartate transferase had a fast transient increase during the first days of growth at 2°C. The concentration of the polyamines putrescine and spermidine exhibited a great increase in all three genotypes, while spermine and cadaverine levels showed only slight changes. Among the genes related to the polyamine metabolism, the transcript level of those ones encoding arginine and ornithine decarboxylase increased and that of the spermidine synthetase did not change. The observed changes in metabolite and transcript levels were controlled by chromosome 5A in the case of Pro, Glu and putrescine. The present result show that free amino acids and polyamines play an important role in the cold acclimation and their levels are regulated at the transcriptional level

Effect of chromosome 5A on gene expression during cold hardening in wheat

Changes in the transcript profile during cold hardening, a treatment necessary for achieving the full level of freezing tolerance, were monitored in a genetic system of wheat (Triticum aestivum L.) chromosome 5A substitution lines differing in their freezing tolerance. The number of cold-responsive genes in a freezing-tolerant substitution line (146) was significantly higher than in a sensitive one (97), indicating a general relationship between the overall number of genes with altered expression and the degree of freezing tolerance. The expression of 175 genes was differentially affected in the freezing-tolerant and sensitive substitution lines. Three of them, coding for a Ca-binding protein (Cab), a cold-responsive protein (Tacr7) and a protein described in a mutant deficient in embryo and meristems (Dem), were characterised in more detail. The expression of Dem was induced only by low temperature, while the transcript level of Cab was also higher following NaCl treatment and that of Tacr7 after salicylic acid and H2O2 application

Effect of combination of light and drought stress on physiology and oxidative metabolism of rice plants

The realized productivity of crop plants is generally lower than the potential productivity due to the influence of one or more external stresses (biotic and abiotic). Simultaneous occurrence of combination of abiotic stresses, which is more common under field condition, results in compounded effect on functional processes. Main focus of the present work is the combined effect of drought and light (irradiance) on rice plants. Potted seedlings of four selected rice lines (viz., IR36, N22, CRD40 and Bhootmuri) were exposed to three different levels of drought stress (50%, 25%, 12.5% of water) along with control (100%) in combination with three different light intensities (high, medium and low) during experimental period. After 7 days of stress, plant height and relative water content (RWC) were relatively low while root length increased with increasing water stress level and light intensity. Protein content increased with increasing water stress and light intensity, while chlorophyll level was higher at higher light intensities. Malondialdehyde (MDA) content, indicative of lipid peroxidation, increased with water stress only at high light intensities. Superoxide dismutase (SOD), peroxidase (POX) and ascorbate peroxidase (APX) activities increased with combined drought and light stress level, whereas catalase (CAT) activity was higher at higher light intensities. On the other hand, superoxide (O2.-) production, but not hydrogen peroxide (H2O2) production was higher with increasing water stress and light intensity. It appears that light-induced ROS (O2.-) production under drought condition provoked oxidative stress, though a potential mechanism of tolerance was apparent through antioxidant system

Effect of heat stress on glutathione biosynthesis in wheat

A relationship was found between the frost sensitivity and glutathione accumulation during cold treatment in wheat. The aim of the present study was to investigate in the same genotypes whether there is also a relationship between the frost sensitivity and the glutathione accumulation during high temperature stress. The glutathione and hyroxymethylglutathione content as well as the activity of the two enzymes of glutathione synthesis was greater in the frost-sensitive genotypes than in the tolerant ones during heat stress. High temperature stress resulted in a greater ratio of the reduced to oxidised non-protein thiols and the greater glutathione reductase activity in the sensitive genotypes. Thus, it can be established that the GSH accumulation induced by heat stress depends on the frost sensitivity of wheat

Effect of salt stress on free amino acid and polyamine content in cereals

The effect of salt stress on the level of free amino acids and polyamines in cereal samples was investigated. Different cereal seedlings were exposed to 0.1 M NaCl. Quantitative determination of amino acids and polyamines were accomplished by chromatographic methods. The results showed genotype dependent changes in free amino acid and polyamine contents. The salt stress caused increases in proline, glutamic acid, aspartic acid, arginine, ornithine and γ-amino-butyric acid levels. With respect to polyamine content, salt stress increased the levels of putescine and decreased the concentration of spermidine

Az alacsonyhőmérsékleti stressz hatására indukálódó regulátor gének vizsgálata búzában = Studying regulatory genes induced at low temperature in wheat

A Cbf gének olyan transzkripciós faktorokat kódolnak, melyek más gének expresszióját szabályozva vesznek részt a növények alacsonyhőmérsékleti stressz-toleranciájának kialakításában. Kutatásaink során két rendszerben, kétféle metodikával azonosítottuk, melyek azok a Cbf gének, amelyek a fagyállóság kialakításában részt vesznek a gabonafélékben. A hexaploid kenyérbúzában génexpressziós kísérletekkel (Northern analízis és Real Time RT-PCR) a Cbf14, Cbf15 és a Cbf16 géneket azonosítottuk, míg a diploid alakorban egy újonnan létrehozott térképezési populáció fagytesztjével a Cbf12, Cbf14 és a Cbf15 gének szerepét igazoltuk. A speciális genetikai anyagon végzett kísérletek lehetővé tették, hogy bizonyítsuk, ezek a gének a fagyállóságot meghatározó Fr-A2 génlókusznak (QTL) megfelelő helyen lokalizálhatók. E regulátorok szerepét a gének transzformációjával tervezzük direkt módon is bizonyítani. | Cbf genes encode cold-induced transcription factors that are involved in the development of plant frost tolerance and cold acclimation. In the current project we have identified the Cbf genes which are involved in the low-temperature stress tolerance in cereals by two independent ways. Studying the expression of these genes by Northern method and Real Time RT-PCR in bred wheat we have proved the role of genes Cbf14, Cbf15 and Cbf16, while the frost tolerance test of a novel einkorn mapping population highlighted the involvement of Cbf12, Cbf14 and Cbf15 genes. Using special genetic stocks we have also proved that these genes are localised under the frost tolerance locus Fr-A2. We plan to verify the involvement of these genes in the regulation of frost tolerance by transformation in the future

Az antioxidánsok és a poli(ADP-ribóz) polimeráz szerepe a gabonafélék abiotikus stresszek által indukált öregedésében = Role of antioxidants and poly(ADP-ribose) polymerase in senescence of cereals induced by abiotic stresses

Az OTKA pályázat keretében azt vizsgáltuk, hogy a különböző antioxidánsok és a poli(ADP-ribóz) polimeráz (PARP) milyen szerepet töltenek be az abiotikus stresszek által előidézett öregedési folyamatokban. Egy hidegtűrő és egy hidegérzékeny kukoricagenotípust különböző abiotikus stresszhatásoknak (extrém hőmérsékletek, ozmotikus stressz) kitéve jelentős különbségeket találtunk a glutation és prekurzorai összmennyiségében és redox állapotában, valamint a thioredoxin h szintjében. Ha e két kukoricagenotípusban a sötétben történő neveléssel idéztük elő az öregedést, a glutation koncentrációjában és oxidáltságánk fokában, valamint a PARP gén expressziójában és a fehérje mennyiségében nagy eltéréseket figyeltünk meg a normál megvilágításban nevelt növényekhez képest. Búza kromoszóma szubsztitúciós vonalakat felhasználva megállapítottuk, hogy azok a gének, melyek a glutation szintézisét és redox állapotát az ozmotikus és a hőstressz során befolyásolják, az 5A kromoszómán találhatók. Transzkriptom-analízissel ki tudtuk mutatni, hogy ez a kromoszóma az antioxidánsok közül a glutation S-transzferáz génjének hideg-indukálta expressziós változásaira is hatással van. Az antioxidánsok és a PARP stresszválaszban és a stressz által előidézett öregedésben betöltött szerepére további bizonyítékokat szereztünk, amikor e vegyületeket olyan növényekben tanulmányoztuk, melyeket különböző gátlószerekkel és növekedésszabályozókkal kezeltünk. | The role of the different antioxidants and poly(ADP-ribose) polymerase (PARP) in the senescence induced by different abiotic stresses was investigated. Subjecting a chilling-tolerant and a chilling-sensitive maize genotype to various abiotic stresses (extreme temperatures, osmotic stress), a great difference was found in the total amount and redox state of glutathione and its precursors and in the concentration of thioredoxin h. If the senescence of these two maize genotypes was induced by cultivation in the continuous dark, a great difference was found in the concentration and redox state of glutathione, in the expression of PARP gene and in the amount of PARP protein compared to the plants grown under normal illumination. Using wheat chromosome substitution lines it was found, that the genes affecting the glutathione synthesis and its redox state during the osmotic and heat stresses are localised on the chromosome 5A. It was shown by transcript profiling that this chromosome also influences from the antioxidants? genes the cold-induced expression changes of the glutathione S-transferase gene. Further evidence for the role of antioxidants and PARP in the stress response and stress-induced senescence was obtained by investigation of these compounds in plants treated with different inhibitors and growth regulators

Az antioxidánsok és a poli(ADP-ribóz) polimeráz szerepe a gabonafélék abiotikus stresszek által indukált öregedésében = Role of antioxidants and poly(ADP-ribose) polymerase in senescence of cereals induced by abiotic stresses

Az OTKA pályázat keretében azt vizsgáltuk, hogy a különböző antioxidánsok és a poli(ADP-ribóz) polimeráz (PARP) milyen szerepet töltenek be az abiotikus stresszek által előidézett öregedési folyamatokban. Egy hidegtűrő és egy hidegérzékeny kukoricagenotípust különböző abiotikus stresszhatásoknak (extrém hőmérsékletek, ozmotikus stressz) kitéve jelentős különbségeket találtunk a glutation és prekurzorai összmennyiségében és redox állapotában, valamint a thioredoxin h szintjében. Ha e két kukoricagenotípusban a sötétben történő neveléssel idéztük elő az öregedést, a glutation koncentrációjában és oxidáltságánk fokában, valamint a PARP gén expressziójában és a fehérje mennyiségében nagy eltéréseket figyeltünk meg a normál megvilágításban nevelt növényekhez képest. Búza kromoszóma szubsztitúciós vonalakat felhasználva megállapítottuk, hogy azok a gének, melyek a glutation szintézisét és redox állapotát az ozmotikus és a hőstressz során befolyásolják, az 5A kromoszómán találhatók. Transzkriptom-analízissel ki tudtuk mutatni, hogy ez a kromoszóma az antioxidánsok közül a glutation S-transzferáz génjének hideg-indukálta expressziós változásaira is hatással van. Az antioxidánsok és a PARP stresszválaszban és a stressz által előidézett öregedésben betöltött szerepére további bizonyítékokat szereztünk, amikor e vegyületeket olyan növényekben tanulmányoztuk, melyeket különböző gátlószerekkel és növekedésszabályozókkal kezeltünk. | The role of the different antioxidants and poly(ADP-ribose) polymerase (PARP) in the senescence induced by different abiotic stresses was investigated. Subjecting a chilling-tolerant and a chilling-sensitive maize genotype to various abiotic stresses (extreme temperatures, osmotic stress), a great difference was found in the total amount and redox state of glutathione and its precursors and in the concentration of thioredoxin h. If the senescence of these two maize genotypes was induced by cultivation in the continuous dark, a great difference was found in the concentration and redox state of glutathione, in the expression of PARP gene and in the amount of PARP protein compared to the plants grown under normal illumination. Using wheat chromosome substitution lines it was found, that the genes affecting the glutathione synthesis and its redox state during the osmotic and heat stresses are localised on the chromosome 5A. It was shown by transcript profiling that this chromosome also influences from the antioxidants? genes the cold-induced expression changes of the glutathione S-transferase gene. Further evidence for the role of antioxidants and PARP in the stress response and stress-induced senescence was obtained by investigation of these compounds in plants treated with different inhibitors and growth regulators

Central role of the flowering repressor ZCCT2 in the redox control of freezing tolerance and the initial development of flower primordia in wheat

Background: As both abiotic stress response and development are under redox control, it was hypothesised that the pharmacological modification of the redox environment would affect the initial development of flower primordia and freezing tolerance in wheat (Triticum aestivum L.).Results: Pharmacologically induced redox changes were monitored in winter (T. ae. ssp. aestivum cv. Cheyenne, Ch) and spring (T. ae. ssp. spelta; Tsp) wheat genotypes grown after germination at 20/17°C for 9 d (chemical treatment: last 3 d), then at 5°C for 21 d (chemical treatment: first 4 d) and subsequently at 20/17°C for 21 d (recovery period). Thiols and their disulphide forms were measured and based on these data reduction potentials were calculated. In the freezing-tolerant Ch the chemical treatments generally increased both the amount of thiol disulphides and the reduction potential after 3 days at 20/17°C. In the freezing-sensitive Tsp a similar effect of the chemicals on these parameters was only observed after the continuation of the treatments for 4 days at 5°C. The applied chemicals slightly decreased root fresh weight and increased freezing tolerance in Ch, whereas they increased shoot fresh weight in Tsp after 4 days at 5°C. As shown after the 3-week recovery at 20/17°C, the initial development of flower primordia was accelerated in Tsp, whereas it was not affected by the treatments in Ch. The chemicals differently affected the expression of ZCCT2 and that of several other genes related to freezing tolerance and initial development of flower primordia in Ch and Tsp after 4 d at 5°C.Conclusions: Various redox-altering compounds and osmotica had differential effects on glutathione disulphide content and reduction potential, and consequently on the expression of the flowering repressor ZCCT2 in the winter wheat Ch and the spring wheat Tsp. We propose that the higher expression of ZCCT2 in Ch may be associated with activation of genes of cold acclimation and its lower expression in Tsp with the induction of genes accelerating initial development of flower primordia. In addition, ZCCT2 may be involved in the coordinated control of the two processes. © 2014 Gulyás et al.; licensee BioMed Central Ltd