Variations in the Levels of Individual Phenolic Compounds in Grapevine Latent Buds during Eco-Dormancy, Following Chemically-Induced Stress Conditions

The goal of viticulture in Greece, where it is one of the country’s briskest economic activities, is satisfying grape yields. Nevertheless, owing to the ongoing climate change, that goal is impeded by a major obstacle in the form of an insufficient period of chilling temperatures which are becoming briefer. Consequently, the shorter period of cold leads to poor budbreak which, in turn, results in reduced yields. In order to meet the chilling requirements that several plants (including the grapevine) require for bud dormancy release, agronomists have resorted to treatments with chemical regulators. This study aimed at identifying and quantifying during eco-dormancy the individual phenolic compounds, together with their possible variations, in the latent buds of the ‘Prime©’ and ‘Ralli’ table grape cultivars. The study induced chemical stress by means of four different solutions, at three discrete dates per year, for three consecutive years. Phenolics were analyzed via HPLC. Their quantitative analysis showed variations both between the varieties and between the samples of those varieties. The analysis indicated that the phenolic content continued progressing during the annual growth cycle. Higher rates of increase in the phenolic content were observed in the first three days following each application, which implies an immediate stress response mechanism. Strong positive correlations were detected between several polyphenols. Luteolin, despite registering a positive correlation with quercetin, resveratrol, o-coumaric, did not do so with the remaining polyphenols. The results confirmed that chemically-induced stress conditions affect the phenolics content. Moreover, depending on the date of application, significant changes appear in the variations of those phenolics.

Melatonin Treatment of Apricot Trees Leads to Maintenance of Fruit Quality Attributes during Storage at Chilling and Non-Chilling Temperatures

The effects of preharvest melatonin treatment on apricot crop yield and fruit quality properties at harvest and during storage have not yet been investigated. Apricot trees, of the ‘Colorado’ and ‘Mikado’ cultivars, were sprayed with 0.1 mM melatonin at three key points of fruit development. Fruit were harvested at commercial ripening stage and yield was higher in melatonin treated trees than in the controls. Fruit were stored at 1 and 8 °C for 21 and 28 days, respectively. Samples were taken weekly and left at 20 °C for 1 day. Weight losses, as well as reduction in firmness and acidity, were delayed in fruits from melatonin treated trees, showing an effect of treatment on delaying the postharvest ripening process, which was attributed to a reduced ethylene production in both cultivars and at both storage temperatures. In addition, chilling injury symptoms were observed in apricots stored at 1 °C, which were reduced by preharvest melatonin treatment. Moreover, apricot from melatonin-treated fruit retained higher total phenolic content than the controls after 14 days of storage, although the phenolic profile was not affected by treatment. Thus, melatonin could be a useful tool for practical purposes to improve apricot crop yield and maintain fruit quality properties during storage.

Variations in phenolic levels in grapevine buds at eco-dormancy after chemically-induced stress conditions

Viticulture is one of the briskest economic activities worldwide. A major obstacle impeding such grape yields to satisfy the demand for increased production is the insufficient period of chilling temperatures which, due to climate change, is becoming briefer. The shorter period of cold leads to poor budbreak which, in turn, results in reduced yields. To combat this issue, agronomists have resorted to treatments with chemical regulators to meet the chilling requirement for bud dormancy release several fruit-bearing plants have, including grapevines. This study aimed at identifying and quantifying during eco-dormancy the individual polyphenolic compounds, and their possible variations, in the latent buds of the 'Prime©' and 'Ralli' table grape cultivars. The study induced chemical stress by means of four different solutions, at three discrete dates per year, for three consecutive years. Phenolics in the latent buds of the studied varieties were analyzed via HPLC. Their quantitative analysis showed variations both between the varieties and between the samples of those varieties collected after the eight treatments. The analysis indicated that the concentration of phenolics continued progressing during the annual growth cycle of the grapevine, with strong positive correlations being detected between catechin, epicatechin, chlorogenic acid, o-coumaric, piceid, procyanidins B1-B2, rutin, ε-viniferin. Luteolin registered a positive correlation with quercetin, resveratrol, o-coumaric, but not with the remaining polyphenols. The results confirmed that (a) the concentration of phenolics of the latent buds is affected by chemically-induced stress conditions, (b) depending on the date of application, significant changes appear in the variations of those phenolics.

Evidence for microbiome-dependent chilling tolerance in Sorghum

Early season chilling stress is a major constraint on sorghum production in temperate climates. Chilling-tolerant sorghum is an active area of development, but the potential for early season microbial-enhanced chilling tolerance in sorghum has not yet been explored. In this study, we characterized traits of field-grown sorghum accessions in response to chilling and non-chilling temperatures, then we characterized the effects of chilling temperatures and microbial inoculation on sorghum accession traits in a growth chamber experiment. By comparing sorghum trait responses under chilling stress with and without soil microbial inoculation, we were able to detect a potential microbe-dependent sorghum response to chilling stress. Four sorghum genotypes show a negative response to chilling stress with vs. without microbial inoculation, while five sorghum accessions show increased shoot biomass or/ and leaf area under chilling stress when inoculated with a soil microbiome.

Carbon Dioxide Pretreatment on Tomatoes Before Cold Storage Synergistically Delays Ripening Through Transcriptional Change of Ethylene-Related Genes and Respiration-Related Metabolisms

The effect of CO2 pre-treatments on tomato quality prior to cold storage was investigated using physiochemical and transcriptome changes. Three hours CO2 treated fruits were firmer than untreated fruits and had a good appearance even after being transferred from 4°C storage to 20°C for 8 d. CO2 pretreatment with cold storage showed a synergistic effect on delayed ripening through reduced respiration; these tomatoes exhibited a lower lycopene content than untreated fruit under cold storage. Tomatoes treated with 30% CO2 had fewer pits than untreated fruits subjected to chilling temperatures, even after being transferred to 20°C for 8 d. Functional enrichment analyses from transcriptome and metabolome commonly showed that CO2-responsive genes or metabolites were involved in the sucrose and starch and biosynthesis of secondary metabolisms. The most frequently detected domain, ethylene-responsive factor domain and reduced glycolysis provide insights into the mechanism that CO2 regulates tomato quality.

A Study on Different Hurdle Factors of Nano Metal Vitamin Complex for the Prevention of Microbial Spoilage in Seafood

Hurdles that have a positive effect by inhibiting microorganisms may have a negative one on other parameters such as nutritional properties or sensory quality, depending on their intensity. In order to lower the preservative level, the hurdle technology concept has been developed, consisting in using combined hurdles to establish an additive antimicrobial effect, and even sometimes a synergetic one, thus improving the safety and the sensory quality of food. The antibacterial and anti-oxidant potential of copper oxide nano particles coupled with vitamin-E (CuONPs+VE) was investigated by applying the novel hurdle factors against seafood pathogens and by studying the cell viability using MTT assays. The hurdle method is proposed to explain the significance of combined use of different preservation factors as synergistic effects instead of using a large-intensity preservation factor. Effect of CuONPs+VE and chilling temperatures (-18°C and +4°C); and Effect of CuONPs+VE and brine salts at various concentrations (5%, 10%,) were evaluated. CuONPs+VE with different chilling temperatures and brine salt concentration showed significant results on compared to control temperatures. Thus CuONPs+VE due to their bacteriostatic activity can be efficiently used in hurdle technology which reduces the food spoiling organisms. Thus CuONPs+VE in combined with hurdle technology can be used as alternatives for chemical preservatives in preservation techniques.

Wood Architecture and Composition Are Deeply Remodeled in Frost Sensitive Eucalyptus Overexpressing CBF/DREB1 Transcription Factors

Eucalypts are the most planted trees worldwide, but most of them are frost sensitive. Overexpressing transcription factors for CRT-repeat binding factors (CBFs) in transgenic Eucalyptus confer cold resistance both in leaves and stems. While wood plays crucial roles in trees and is affected by environmental cues, its potential role in adaptation to cold stress has been neglected. Here, we addressed this question by investigating the changes occurring in wood in response to the overexpression of two CBFs, taking advantage of available transgenic Eucalyptus lines. We performed histological, biochemical, and transcriptomic analyses on xylem samples. CBF ectopic expression led to a reduction of both primary and secondary growth, and triggered changes in xylem architecture with smaller and more frequent vessels and fibers exhibiting reduced lumens. In addition, lignin content and syringyl/guaiacyl (S/G) ratio increased. Consistently, many genes of the phenylpropanoid and lignin branch pathway were upregulated. Most of the features of xylem remodeling induced by CBF overexpression are reminiscent of those observed after long exposure of Eucalyptus trees to chilling temperatures. Altogether, these results suggest that CBF plays a central role in the cross-talk between response to cold and wood formation and that the remodeling of wood is part of the adaptive strategies to face cold stress.