Rice is one of the few crops able to withstand periods of partial or even complete submergence. One of the adaptive traits of rice is the constitutive presence and further development of aerenchyma which enables oxygen to be transported to submerged organs. The development of lysigenous aerenchyma is promoted by ethylene accumulating within the submerged plant tissues, although other signalling mechanisms may also co-exist. In this study, aerenchyma development was analysed in two rice (Oryza sativa) varieties, ‘FR13A’ and ‘Arborio Precoce’, which show opposite traits in flooding response in terms of internode elongation and survival. The growth and survival of rice varieties under submergence was investigated in the leaf sheath of ‘FR13A’ and ‘Arborio Precoce’. The possible involvement of ethylene and reactive oxygen species (ROS) was evaluated in relation to aerenchyma formation. Cell viability and DNA fragmentation were determined by FDA/FM4-64 staining and TUNEL assay, respectively. Ethylene production was monitored by gas chromatography and by analysing ACO gene expression. ROS production was measured by using Amplex Red assay kit and the fluorescent dye DCFH₂-DA. The expression of APX1 was also evaluated. AVG and DPI solutions were used to test the effect of inhibiting ethylene biosynthesis and ROS production, respectively. Both the varieties displayed constitutive lysigenous aerenchyma formation, which was further enhanced when submerged. ‘Arborio Precoce’, which is characterized by fast elongation when submerged, showed active ethylene biosynthetic machinery associated with increased aerenchymatous areas. ‘FR13A’, which harbours the Sub1A gene that limits growth during oxygen deprivation, did not show any increase in ethylene production after submersion but still displayed increased aerenchyma. Hydrogen peroxide levels increased in ‘FR13A’ but not in ‘Arborio Precoce’. While ethylene controls aerenchyma formation in the fast-elongating ‘Arborio Precoce’ variety, in ‘FR13A’ ROS accumulation plays an important role.

The present work set out to define the processes involved in the early O₃‐induced H₂O₂ accumulation in sunflower plants exposed to a single pulse of 150 ppb of O₃ for 4 h. Hydrogen peroxide accumulation only occurred in the apoplast and this temporally coincided with the fumigation period. The inhibitor experiments suggested that both the plasma membrane‐bound NAD(P)H oxidase complex and cell‐wall NAD(P)H PODs contributed to H₂O₂ generation. To investigate the mechanisms responsible for O₃‐induced H₂O₂ accumulation further, both production and scavenging of H₂O₂ were investigated in the extracellular matrix after subcellular fractionation. The results indicated that H₂O₂ accumulation is a complex and highly regulated event requiring the time‐dependent stimulation and down‐regulation of differently located enzymes, some of which are involved in H₂O₂ generation and degradation, not only during the fumigation period but also in the subsequent recovery period in non‐polluted air. Owing to the possible interplay between H₂O₂ and ethylene, the time‐course of ethylene emission was analysed too. Ethylene was rapidly emitted following O₃ exposure, but it declined to control values as early as after 4 h of exposure. The early contemporaneous detection of increased ethylene and H₂O₂ levels after 30 min of exposure does not allow a clear temporal relationship between these two signalling molecules to be established.

While the ongoing global warming and the economic crisis threaten horticultural and ornamental products production in the Mediterranean region, new challenges and opportunities for renewing plant material occur. Pitaya has great potential as a new crop for Mediterranean growers: it consumes little water and it adapts well to the high temperatures present in the greenhouse. Moreover, the market shows increasing demand of new, healthy exotic fruits and the fruit of these crops are worldwide appreciated as a super fruits. The aim of this study was to investigate the potential of introducing a new type of product that in addition to the aesthetic value can combine functional nutritional characteristics, through a whole chain approach, in order to develop basic knowledges and technical information that may lead to the commercial production of pitaya by small-scale farmers in Italy. The results of this study report and discuss various aspects to support the establishment of pitaya cultivation, such as its propagation by cuttings and micropropagation, greenhouse cultivation practices (through the clarification of the sprouting and flowering phenology as well as the fruit maturation period), while providing also information on the sensory properties and the antioxidant levels which naturally occurring in these fruits.

Summary: Low oxygen availability often is associated with soil waterlogging or submergence, but may occur also as hypoxic niches in otherwise aerobic tissues. Experimental evidence assigns a role in Botrytis cinerea resistance to a group of oxygen‐unstable Ethylene Response Factors (ERF‐VII). Given that infection by B. cinerea often occurs in aerobic organs such as leaves, where ERF‐VII stability should be compromised, we explored the possibility of local leaf hypoxia at the site of infection. We analyzed the expression of hypoxia‐responsive genes in infected leaves. Confocal microscopy was utilized to verify the localization of the ERF‐VII protein RAP2.12. Oxygen concentration was measured to evaluate the availability of oxygen (O₂). We discovered that infection by B. cinerea induces increased respiration, leading to a drastic drop in the O₂ concentration in an otherwise fully aerobic leaf. The establishment of a local hypoxic area results in stabilization and nuclear relocalization of RAP2.12. The possible roles of defence elicitors, ABA and ethylene were evaluated. Local hypoxia at the site of B. cinerea infection allows the stabilization of ERF‐VII proteins. Hypoxia at the site of pathogen infection generates a nearly O₂‐free environment that may affect the stability of other N‐degron‐regulated proteins as well as the metabolism of elicitors.