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

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

REFLECTION OF ENVIRONMENTAL STRESSES ON THE AMINO ACID COMPOSITION OF WHEAT

The adaptation of wheat to different environmental stresses (drought and cold) was studied. The role of amino acids in this process is well known. Stress induced free amino acid accumulation was compared in tissue cultures and in seedlings. The range of studied species included Chinese Spring, Cappelle Desprez and Cheyenne wheat varieties, as well as disomic chromosome substitution lines of Cappelle Desprez into Chinese Spring and Cheyenne into Chinese Spring .. The profile of free amino acid accumulations caused by stress conditions was found to depend on the stress tolerance of the varieties and the nature of the treatment. The results suggested that there is a link between the drought and frost tolerance of wheat. We have found that chromosomes 5A and 5D were associated with both osmotic and cold stress induced free amino acid accumulation

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

Key Molecular and Metabolic Processes Used for Genetic Engineering to Improve Freezing Tolerance in Cereals

It has been estimated recently that cereals are harvested on 700 million hectares (Mha) worldwide (Dunwell, 2014), and also that, due to low temperature damage, worldwide losses in crop production amount to about US$2 billion each year (Sanghera et al., 2011). In spite of the urgent need for more cold- or frost-tolerant cereal varieties, classical breeding programmes have shown limited progress in improving freezing tolerance (Thomashow, 1999). This lack of success is due mainly to the fact that the physiological process, i.e. the cold acclimation that leads to the development of freezing tolerance, is quite a complex quantitative trait. However, the deeper insight provided by different ‘omics’ technologies has made possible knowledge-based engineering of more stress-resistant plants; while the recent developments in cereal transformation methodology offer the technology to realize these aims. Since many recently published book chapters and reviews summarize our current knowledge on plant abiotic stress tolerance, this chapter focuses particularly on freezing tolerance, especially in cereals

Signaling components in the cold stress response of barley

As a consequence of climate change, occurrence of erratic weather conditions is increased generating temperature, drought or osmotic stress for cereals and other cultivated plants causing significant loss of production and decrease of yield. This phenomenon intensified the need for enhanced abiotic stress tolerance in cereals. To improve the adaptation ability of the crop plants, it is very important to understand how these plants are able to percept environmental signals and how these signals are converted to molecular response in the plants. Thus, the investigation of the major signal transduction mechanisms and identification of signaling components involved in abiotic stress tolerance is very important not only in model organisms, but in cultivated plants as well. In the present work components of the phospholipid signaling were identified and investigated in barley and their influence on the cold response was also studied. In details, a phosphatidylinositol transfer protein and a phosphatidylinositol 4-kinase were identified in barley using homology search and their biochemical and cell biological characterization was performed. Moreover, the role of this signaling pathway in the cold regulation of the CBF transcription factors was also studied