Multispecies transcriptomes reveal core fruit development genes

During angiosperm evolution there have been repeated transitions from an ancestral dry fruit to a derived fleshy fruit, often with dramatic ecological and economic consequences. Following the transition to fleshy fruits, domestication may also dramatically alter the fruit phenotype via artificial selection. Although the morphologies of these fruits are well documented, relatively less is known about the molecular basis of these developmental and evolutionary shifts. We generated RNA-seq libraries from pericarp tissue of desert tobacco and both cultivated and wild tomato species at common developmental time points and combined this with corresponding, publicly available data from Arabidopsis and melon. With this broadly sampled dataset consisting of dry/fleshy fruits and wild/domesticated species, we applied novel bioinformatic methods to investigate conserved and divergent patterns of gene expression during fruit development and evolution. A small set of 121 orthologous "core" fruit development genes show a common pattern of expression across all five species. These include key players in developmental patterning such as orthologs of KNOLLE, PERIANTHIA, and ARGONAUTE7. GO term enrichment suggests that these genes function in basic cell division processes, cell wall biosynthesis, and developmental patterning. We furthermore uncovered a number of "accessory" genes with conserved expression patterns within but not among fruit types, and whose functional enrichment highlights the conspicuous differences between these phenotypic classes. We observe striking conservation of gene expression patterns despite large evolutionary distances, and dramatic phenotypic shifts, suggesting a conserved function for a small subset of core fruit development genes.

Impact of Cold Atmospheric Plasma (CAP) Treatments on the Oxidation of Pistachio Kernel Lipids

Cold atmospheric plasma (CAP) is a non-thermal technology that could be applied for food decontamination from both biological (microorganisms) and chemical (pesticides, food allergens, mycotoxins) contaminants, thanks to the production of reactive species (RS). However, RS could also promote the onset and the progress of food lipid oxidation, which may limit the quality and acceptability of the final products. The aim of this work was to assess the oxidation degree of pistachio kernels after treatment in a surface dielectric barrier discharge (SDBD). Two different operative conditions for CAP generation were investigated, resulting in the production of high (800 ppm) or low (300 ppm) concentrations of ozone. Limited amounts of hydroperoxides (3.00–4.22 mEq O₂/kg), thiobarbituric acid reactive substances (TBARS, 0.072–0.600 mg TEP/g oil), and phytosterol oxidation products (POPs, 14.43–17.20 μg/g) were observed in lipids of both control and plasma processed pistachios. Plasma treatments did not significantly affect the total fatty acid composition and the amounts of identified unsaponifiable matter constituents (4-desmethylsterols, 4,4-dimethylsterols, 4-methylsterols), except for an unexpected significant increase of γ-tocopherol content in extracted oils. These findings contribute to gaining further knowledge for the scale-up of CAP technology to industrial processing.

Phylogenetic conservatism explains why plants are more likely to produce fleshy fruits in the tropics

Plant functional traits often show strong latitudinal trends. To explain these trends, studies have often focused on environmental variables, correlations with other traits that themselves show latitudinal trends, and phylogenetic conservatism. However, few studies have systematically disentangled the relative contributions of these factors. Using a dataset consisting of 9,370 plant species from Southwest China, we investigated factors affecting fruit type (fleshy vs. dry): plant growth form, environmental constraints (summarized by climate region), and phylogenetic conservatism. Growth form and climate region are often cited in the literature as important explanations for the higher proportion of fleshy fruited species in the tropics. Nonetheless, in our analyses using partial R² , growth form and climate region explained only 1.7% and 0.3%, respectively, of the variance in fruit type in a model including phylogeny, while phylogenetic conservatism explained 79.5%. Furthermore, phylogenetic conservatism was evenly distributed along the phylogeny, implying that fruit type reflects both ancient and recent phylogenetic relationships. Our findings illustrate the value of parsing out the contributions of explanatory variables and phylogeny to the variance in species' traits. Methods using phylogenies that calculate partial R² give a more informative tool than traditional methods to explore the phylogenetic patterns of functional traits.

Analysis and quantification of naturally occurring aflatoxin B1 in dry fruits with subsequent physical and biological detoxification

Current research involves extraction, identification and detoxification of mycotoxins from ten dry fruit samples. Mycotoxins were identified by high performance thin layer chromatography followed by physical and biological detoxification, analysed by HPLC. Three fungal species were observed after isolation including, Aspergillus niger, Aspergillus flavus and Fussarium sp. HP-TLC analysis revealed the presence of mycotoxin, aflatoxin B1 ranging from 0.000303-0.03636 mg/kg in all samples. Results were further analysed through various statistical tests. Detoxification methods proved to be cost effective and easily implementable. Concentration of aflatoxin B1 in pine nuts was reduced to 0.0043 mg/kg and 0.0039 mg/kg in dry dates through UV based detoxification. Solarisation reduced the concentration of aflatoxin B1 in figs to 0.0044 mg/kg. 90% aflatoxins were detoxified by UV treatment while Zingiber officinale powder detoxified 90% mycotoxin. This research concludes that the studied detoxification methods can be generalised on larger scale to benefit the dry fruit industry worldwide.

Fruit ripening: the role of hormones, cell wall modifications, and their relationship with pathogens

Fruits result from complex biological processes that begin soon after fertilization. Among these processes are cell division and expansion, accumulation of secondary metabolites, and an increase in carbohydrate biosynthesis. Later fruit ripening is accomplished by chlorophyll degradation and cell wall lysis. Fruit maturation is an essential step to optimize seed dispersal, and is controlled by a complex network of transcription factors and genetic regulators that are strongly influenced by phytohormones. Abscisic acid (ABA) and ethylene are the major regulators of ripening and senescence in both dry and fleshy fruits, as demonstrated by numerous ripening-defective mutants, effects of exogenous hormone application, and transcriptome analyses. While ethylene is the best characterized player in the final step of a fruit's life, ABA also has a key regulatory role, promoting ethylene production and acting as a stress-related hormone in response to drought and pathogen attack. In this review, we focus on the role of ABA and ethylene in relation to the interconnected biotic and abiotic phenomena that affect ripening and senescence. We integrate and discuss the most recent data available regarding these biological processes, which are crucial for post-harvest fruit conservation and for food safety.

Evolution and Diversification of FRUITFULL Genes in Solanaceae

Ecologically and economically important fleshy edible fruits have evolved from dry fruit numerous times during angiosperm diversification. However, the molecular mechanisms that underlie these shifts are unknown. In the Solanaceae there has been a major shift to fleshy fruits in the subfamily Solanoideae. Evidence suggests that an ortholog of FRUITFULL (FUL), a transcription factor that regulates cell proliferation and limits the dehiscence zone in the silique of Arabidopsis, plays a similar role in dry-fruited Solanaceae. However, studies have shown that FUL orthologs have taken on new functions in fleshy fruit development, including regulating elements of tomato ripening such as pigment accumulation. FUL belongs to the core eudicot euFUL clade of the angiosperm AP1/FUL gene lineage. The euFUL genes fall into two paralogous clades, euFULI and euFULII. While most core eudicots have one gene in each clade, Solanaceae have two: FUL1 and FUL2 in the former, and MBP10 and MBP20 in the latter. We characterized the evolution of the euFUL genes to identify changes that might be correlated with the origin of fleshy fruit in Solanaceae. Our analyses revealed that the Solanaceae FUL1 and FUL2 clades probably originated through an early whole genome multiplication event. By contrast, the data suggest that the MBP10 and MBP20 clades are the result of a later tandem duplication event. MBP10 is expressed at weak to moderate levels, and its atypical short first intron lacks putative transcription factor binding sites, indicating possible pseudogenization. Consistent with this, our analyses show that MBP10 is evolving at a faster rate compared to MBP20. Our analyses found that Solanaceae euFUL gene duplications, evolutionary rates, and changes in protein residues and expression patterns are not correlated with the shift in fruit type. This suggests deeper analyses are needed to identify the mechanism underlying the change in FUL ortholog function.

A randomized study of raisins versus alternative snacks on glycemic control and other cardiovascular risk factors in patients with type 2 diabetes mellitus

Just as the type and duration of physical activity can have variable effects on the glucose levels and other cardiometabolic parameters among patients with type 2 diabetes mellitus (T2DM), so can the types of foods have variable effects as well. This 12-week randomized study of 51 study participants evaluated the impact of routine consumption of dark raisins versus alternative processed snacks on glucose levels and other cardiovascular risk factors among patients with type T2DM. In this study, compared to alternative processed snacks, those who consumed raisins had a significant 23% reduction in postprandial glucose levels (P = 0.024). Also compared to snacks, those who consumed raisins had a 19% reduction in fasting glucose and 0.12% reduction in hemoglobin A1c, although these latter findings did not achieve statistical significance. Regarding blood pressure, compared to alternative processed snacks, those who consumed raisins had a significant 8.7 mmHg reduction in systolic blood pressure (P = 0.035) (7.5% [P = 0.031]) but did not experience a significant reduction in diastolic blood pressure. Compared to alternative processed snacks, those who consumed raisins did not have a significant improvement in body weight, body mass index, waist circumference, fasting insulin, homeostatic model assessment of insulin resistance, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL), triglyceride, or non-HDL cholesterol levels. Overall, these data support raisins as a healthy alternative compare to processed snacks in patients with T2DM.