ANNALISA PARADISO

Grain protein content (GPC), is one of the most important trait in wheat and its characterized by a very complex genetic control. The identification of wheat varieties with high GPC (HGPC), as well as the characterization of central enzymes involved in these processes, are important for more sustainable agricultural practices. In this study, we focused on Glutamine synthetase (GS) as a candidate to study GPC in wheat. We analyzed GS expression and its enzymatic activity in different tissues and phenological stages in 10 durum wheat genotypes with different GPC. Although each genotype performed quite differently from the others, both because their genetic variability and their adaptability to specific environmental conditions, the highest GS activity and expression were found in genotypes with HGPC and vice versa the lowest ones in genotypes with low GPC (LGPC). Moreover, in genotypes contrasting in GPC bred at different nitrogen regimes (0, 60, 140 N Unit/ha) GS behaved differently ...

Programmed cell death (PCD) is a process of genetically encoded and actively controlled cellular suicide. PCD is associated with different phases of plant life and also represents a defence mechanism that plants activate against different kinds of biotic and abiotic stresses. Reactive oxygen species (ROS) and nitric oxide (NO) have been proposed as key factors in the control of both developmentally and environmentally induced PCD. In this chapter, we give an overview of ROS and NO interplay in the signaling leading to PCD induced in senescence, self-incompatibility, hypersensitive response and under cadmium and heat stress. The data presented indicate that ROS and NO interact through different pathways, depending on the level and the timing of production of these reactive species, the cellular redox state and the plant species. Despite the complicate network of signals, some common points of NO/ROS crosstalk in the different kinds of PCD can be identified. First, during PCD, ROS and NO biosynthesis is mutually regulated with feedback mechanisms. The NO-dependent S-nitrosylation of proteins controlling ROS levels represents a key point of interaction of the two species. Furthermore, NO and ROS interplay could amplify the induction of PCD executors, such as caspase-3-like. Finally, NO and/or ROS might control the ubiquitin–proteasome pathway involved in PCD induction.

Climate change predictions indicate a progressive increase in average temperatures and an increase in the frequency of heatwaves, which will have a negative impact on crop productivity. Over the last decade, a number of studies have addressed the question of how model plants or specific crops modify their metabolism when exposed to heat stress. This review provides an overview of the redox pathways that contribute to how plants cope with heat stress. The focus is on the role of reactive oxygen species (ROS), redox metabolites and enzymes in the signalling pathways leading to the activation of defence responses. Additional attention is paid to the regulating mechanisms that lead to an increase in specific ROS-scavenging systems during heat stress, which have been studied in different model systems. Finally, increasing thermo-tolerance in model and crop plants by exposing them to heat acclimation or to exogenous treatments is discussed. Although there is clear evidence that several st...

The alteration of growth patterns, through the adjustment of cell division and expansion, is a characteristic response of plants to environmental stress. In order to study this response in more depth, the effect of heat stress on growth was investigated in tobacco BY-2 cells. The results indicate that heat stress inhibited cell division, by slowing cell cycle progression. Cells were stopped in the pre-mitotic phases, as shown by the increased expression of CycD3-1 and by the decrease in the NtCycA13, NtCyc29 and CDKB1-1 transcripts. The decrease in cell length and the reduced expression of Nt-EXPA5 indicated that cell expansion was also inhibited. Since DNA methylation plays a key role in controlling gene expression, the possibility that the altered expression of genes involved in the control of cell growth, observed during heat stress, could be due to changes in the methylation state of their promoters was investigated. The results show that the altered expression of CycD3-1 and Nt...

Heat stress can have deleterious effects on plant growth by impairing several physiological processes. Plants have several defense mechanisms that enable them to cope with high temperatures. The synthesis and accumulation of heat shock proteins (HSPs), as well as the maintenance of an opportune redox balance play key roles in conferring thermotolerance to plants. In this study changes in redox parameters, the activity and/or expression of reactive oxygen species (ROS) scavenging enzymes and the expression of two HSPs were studied in tobacco Bright Yellow‐2 (TBY‐2) cells subjected to moderate short‐term heat stress (SHS) and long‐term heat stress (LHS). The results indicate that TBY‐2 cells subjected to SHS suddenly and transiently enhance antioxidant systems, thus maintaining redox homeostasis and avoiding oxidative damage. The simultaneous increase in HSPs overcomes the SHS and maintains the metabolic functionality of cells. In contrast the exposure of cells to LHS significantly re...

BACKGROUND: Glufosinate‐ammonium (GA) is used for chemical vine killing of potato crop before harvest. Over two years we tested the effect of GA, applied at 0.48 kg ha−1 of active ingredient, on desiccation of haulms, yield and some qualitative traits of tubers of three cultivars of early potatoes, a typical crop of southern Italy and large areas of the Mediterranean countries.RESULTS: Seven days after treatment desiccation reached 90% of leaves for all cultivars. At harvest, the highest desiccation percentage of haulms was 85% in Spunta. The desiccant did not affect yield in either year during which the analysis was carried out, but it increased the percentage of tubers in the range of 35–70 mm in diameter. In the first year, the treatment decreased dry matter and vitamin C content and increased free sugar concentration in tubers. In the second year, no negative effects on the nutritional traits were observed. Strong differences were found on yield and quality between the two years...

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