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Plant tissue in vitro culture is increasingly used in agriculture to improve crop production, nutritional quality, and commercial value. In plant virology, the technique is used as sanitation protocol to produce virus‐free plants. Sanitized (S) artichokes show increased vigour compared to their non‐sanitized (NS) counterparts, because viral infections lead to a decline of growth and development.To investigate mechanisms that control the complex traits related to morphology, growth, and yield in S artichokes compared to NS plants, RNAseq analysis and phenotyping by imaging were used. The role of peroxidases (POD) was also investigated to understand their involvement in sanitized plant development.Results showed that virus infection affected regulation of cell cycle, gene expression and signal transduction modulating cellular response to stimulus/stress. Moreover, primary metabolism and photosynthesis were also influenced, contributing to explain the main morphological differences observed between S and NS artichokes. Sanitized artichokes are also characterized by higher POD activity, probably associated with increased plant growth, rather than strengthening of cell walls.Overall, results show that the differences in development of S artichokes may be derived from the in vitro culture stressor, as well as through pathogen elimination, which, in turn, improve qualitative and quantitative artichoke production. [ABSTRACT FROM AUTHOR]

Rising daily temperatures and water shortage are two of the major concerns in agriculture.In this work, we analysed the tolerance traits in a tomato line carrying a small region of the Solanum pennellii wild genome (IL12‐4‐SL) when grown under prolonged conditions of single and combined high temperature and water stress.When exposed to stress, IL12‐4‐SL showed higher heat tolerance than the cultivated line M82 at morphological, physiological, and biochemical levels. Moreover, under stress IL12‐4‐SL produced more flowers than M82, also characterized by higher pollen viability. In both lines, water stress negatively affected photosynthesis more than heat alone, whereas the combined stress did not further exacerbate the negative impacts of drought on this trait. Despite an observed decrease in carbon fixation, the quantum yield of PSII linear electron transport in IL12‐4‐SL was not affected by stress, thereby indicating that photochemical processes other than CO2 fixation acted to maintain the electron chain in oxidized state and prevent photodamage. The ability of IL12‐4‐SL to tolerate abiotic stress was also related to the intrinsic ability of this line to accumulate ascorbic acid.The data collected in this study clearly indicate improved tolerance to single and combined abiotic stress for IL12‐4‐SL, making this line a promising one for cultivation in a climate scenario characterized by frequent and long‐lasting heatwaves and low rainfall. [ABSTRACT FROM AUTHOR]

Climate change is increasing the frequency of high temperature shocks and water shortages, pointing to the need to develop novel tolerant varieties and to understand the mechanisms employed to withstand combined abiotic stresses.Two tomato genotypes, a heat‐tolerant Solanum lycopersicum accession (LA3120) and a novel genotype (E42), previously selected as a stable yielding genotype under high temperatures, were exposed to single and combined water and heat stress. Plant functional traits, pollen viability and physiological (leaf gas exchange and chlorophyll a fluorescence emission measurements) and biochemical (antioxidant content and antioxidant enzyme activity) measurements were carried out. A Reduced Representation Sequencing approach allowed exploration of the genetic variability of both genotypes to identify candidate genes that could regulate stress responses.Both abiotic stresses had a severe impact on plant growth parameters and on the reproductive phase of development. Growth parameters and leaf gas exchange measurements revealed that the two genotypes used different physiological strategies to overcome individual and combined stresses, with E42 having a more efficient capacity to utilize the limiting water resources. Activation of antioxidant defence mechanisms seemed to be critical for both genotypes to counteract combined abiotic stresses. Candidate genes were identified that could explain the different physiological responses to stress observed in E42 compared with LA3120.Results here obtained have shown how new tomato genetic resources can be a valuable source of traits for adaptation to combined abiotic stresses and should be used in breeding programmes to improve stress tolerance in commercial varieties. [ABSTRACT FROM AUTHOR]

Kernel development and maturation involve several well-characterised events, such as changes in ascorbate (ASC) metabolism, protein synthesis and storage, programmed cell death (PCD) of starchy endosperm and tissue dehydration. Despite many studies focusing on these events, whether and how they are metabolically related to each other, remains to be elucidated. In the present investigation, the changes in ASC-related metabolism, PCD occurrence, kernel filling and dehydration have been analysed during kernel maturation, over a 3-year period in plants grown under normal conditions and in plants displaying modified ASC synthesis. The obtained results suggest that ASC plays a pivotal role in the network of events characterising kernel maturation. During this process, a decrease in ASC content occurs. When ASC biosynthesis is improved in the kernel, by feeding the plants with its immediate precursor, L-galactone-γ-lactone (GL), the decrease in ASC, observed during kernel maturation, is delayed. As a consequence, ascorbate peroxidase (APX) activity is also enhanced. Moreover, a delay in the ASC decrease permits a delay in PCD occurring in kernel storage tissues and in kernel dehydration. Interestingly, the data emerging from the present investigation suggest that the delay in the decrease in ASC content and APX activity also improves kernel filling. The relevance of the ascorbate-dependent redox regulation for kernel productivity is discussed. [ABSTRACT FROM AUTHOR]

ABSTRACT Programmed cell death (PCD) is a genetically controlled process described both in eukaryotic and prokaryotic organisms. Even if it is clear that PCD occurs in plants, in response to various developmental and environmental stimuli, the signalling pathways involved in the triggering of this cell suicide remain to be characterized. In this review, the main similarities and differences in the players involved in plant and animal PCD are outlined. Particular attention is paid to the role of reactive oxygen species (ROS) as key inducers of PCD in plants. The involvement of different kinds of ROS, different sites of ROS production, as well as their interaction with other molecules, is crucial in activating PCD in response to specific stimuli. Moreover, the importance is stressed on the balance between ROS production and scavenging, in various cell compartments, for the activation of specific steps in the signalling pathways triggering this cell suicide process. The review focuses on the complexity of the interplay between ROS and antioxidant molecules and enzymes in determining the most suitable redox environment required for the occurrence of different forms of PCD. [ABSTRACT FROM AUTHOR]

Partially purified protein extracts of Catharanthus roseus leaves were able to couple catharanthine and vindoline to produce &alpha3'4'- anhydrovinblastine (AVLB) in a reaction strictly dependent on H2O2. This result, and the co-purification of peroxidase with AVLB synthetase activity, strongly suggest a peroxidase-like nature for the coupling enzyme. Only one peroxidase isoenzyme was detected in C. roseus leaves, and it was shown that this isoenzyme consists of a molecularly-heterogeneous basic peroxidase (EC 1.11.1.7) mainly located in the vacoule. This results suggest that a basic peroxidase located in the vacoule may be the main enzyme responsible for AVLB synthesis in C. roseus leaves. This isoenzyme was also found in cell walls where a peroxidase inhibitor was detected. [ABSTRACT FROM AUTHOR]

Embryos from dry caryopses of wheat (Triticum durum L. cv. Norba) are completely devoid of ascorbate (ASC) but contain a low amount of dehydroascorbate (DHA). The de novo biosynthesis of ASC starts in the wheat embryos after 8–10 h of germination but before the ASC biosynthetic pathway is completely restored the embryos can provide themselves with ASC by the reduction of the stored DHA. Three different proteins having DHA-reducing capability are present in the embryos during the early stages of germination. However, when the de novo ASC biosynthesis from sugar is completely restored, the DHA reduction capability largely drops and only one DHA-reducing protein remains active. The presence of three proteins having DHA-reducing capability and their behaviour during germination is discussed. Dry embryos are also devoid of ASC peroxidase (EC 1.11.1.11); this hydrogen peroxide scavenger enzyme appears after the same lag as ASC and increases during germination in parallel with the rise in ASC. When ASC biosynthesis is experimentally induced, the ASC peroxidase also appears earlier; moreover the affinities for ASC of the three ASC peroxidase isoenzymes that progressively appear during germination depend on the ASC available in the embryos: highest in the first isoenzyme, that appears when the ASC content is very low, lowest in the isoenzyme that is expressed last, when the ASC content is 10–11 times higher. [ABSTRACT FROM AUTHOR]