379 research outputs found
Fruit development and ripening: a molecular and physiological view modulating and enhancing fruit quality
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Piriformospora indica-primed transcriptional reprogramming induces defense response against early blight in tomato
No full textPiriformospora indica is an adaptable mycorrhiza-like fungus belonging to the Sebacinales order that can colonize roots of a wide range of plant species. Studies have shown that P. indica improves growth and enhances systemic defense against pathogens in host plants. However, the mechanism(s) through which these effects occur remain unclear. Therefore to gain more insight into the molecular basis of P. indica induced resistance, cDNA-AFLP (Amplified fragment length polymorphism) based transcript profiling was done to identify differentially expressed genes in P. indica-colonized tomato plants infected with Alternaria solani. Our results demonstrated that pre-colonization of tomato roots with P. indica systemically induced resistance against early blight. Transcript profiling of P. indica pre-colonized tomato plants revealed systemic modulation of several key components of signaling network transcriptional regulators including CBL-interacting protein kinase (CIPK), Mitogen activated protein kinases (MPKs), Lipid transfer proteins (LTPs), WRKY1, ethylene responsive transcription factors (ERF), and Jasmonate Zim Domain 1 (JAZ1), a negative regulator of jasmonic acid (JA) signaling. Expression of downstream defense related genes like Thaumatin-like protein, β-1, 3-glucanase and chitinases was also affected in leaves upon challenge inoculation with pathogen. Interestingly, P. indica pre-colonization alone was unable to induce transcript levels for most of the genes studied. However, pathogen attack on P. indica pre-colonized plants induced strong defense responses. In conclusion, P. indica induces transcriptome reprogramming in a manner that allows rapid and efficient activation of JA/ET (jasmonic acid/ethylene)-mediated basal defenses against pathogen infection by altering the expression of JA/ET related genes. P. indica colonization appears to potentiate the complete signal transduction cascade leading to the systemic expression of defense genes against foliar pathogens. It thus presents itself as a potential and sustainable method of activating multiple components of defense signaling thereby conveying durable horizontal defense against a range of pathogen
Ripening behavior in red flesh ‘Kissabel®’ apple fruit during postharvest
No full textIn the last few years, the cultivation of red flesh apple cultivars received great attention due to their novelty and valuable nutraceutical properties, considering their higher anthocyanin and phenols content than white flesh apple cultivars. Nevertheless, red flesh cultivars can be characterized by a low storability, being therefore prone to develop internal browning disorder. In this preliminary work, we investigated the postharvest ripening behavior of the red flesh apple R201-‘Kissabel®’, a late season cultivar, in comparison with the white pulp apple ‘Golden Delicious’, generally considered as the standard reference cultivar for apple. For this purpose, fruit were collected at commercial harvest and kept for one month at room temperature in regular atmosphere. The cortex of five apple was sampled every two days along this period. Total RNA was extracted, reverse transcribed and RT-qPCR were performed on specific ripening related genes, such as ethylene biosynthetic genes (MdACS3, MdACS1 and MdACO1) and the polygalacturonase-1 (MdPG1). Moreover, proton-transferreaction mass spectrometry (PTR-ToF-MS) was employed to quantify ethylene evolution during the stored period. In ‘Kissabel®’, ethylene started to be accumulated immediately after harvest, and one week earlier than ‘Golden Delicious’. Moreover, both cultivars showed a first peak at 9 and 16 days after harvest (DAH) and a second one at 14 and 21 DHA, respectively. Based on the expression profile of selected genes, the first peak coincided with the ripening onset. In ‘Golden Delicious’, indeed, the highest expression level, for all genes, corresponded with the maximum of ethylene production at 16 DAH. In ‘Kissabel®’ the maximum expression was instead detected two days earlier respect the ethylene burst, while the expression pattern of MdACS3 decreased immediately after harvest in both cultivars, as expected. These results represent the first step to better characterize the ripening behavior and storability of this new apple cultiva
Climacteric ripening of apple fruit is regulated by transcriptional circuits stimulated by cross-talks between ethylene and auxin
No full textApple is a fleshy fruit distinguished by a climacteric type of ripening, since most of the relevant physiological changes are triggered and governed by the action of ethylene. After its production, this hormone is perceived by a series of receptors to regulate, through a signaling cascade, downstream ethylene related genes. The possibility to control the effect of ethylene opened new horizons to the improvement of the postharvest fruit quality. To this end, 1-methylcyclopropene (1-MCP), an ethylene antagonist, is routinely used to modulate the ripening progression increasing storage life. In a recent work published in The Plant Journal, the whole transcriptome variation throughout fruit development and ripening, with the adjunct comparison between normal and impaired postharvest ripening, has been illustrated. In particular, besides the expected downregulation of ethylene-regulated genes, we shed light on a regulatory circuit leading to de-repressing the expression of a specific set of genes following 1-MCP treatment, such as AUX/IAA, NAC and MADS. These findings suggested the existence of a possible ethylene/auxin cross-talk in apple, regulated by a transcriptional circuit stimulated by the interference at the ethylene receptor leve
Peach ripening transcriptomics unveils new and unexpected targets for the improvement of drupe quality
No full textMultifaceted analyses disclose the role of fruit size and skin-russeting in the accumulation pattern of phenolic compounds in apple
No full textFruits are nowadays considered important suppliers of anti-oxidant molecules. Apples are
particularly rich in phenolic compounds, non-nutritional phytochemicals that play active
roles in controlling severe chronic diseases. In this work, 19 phenolic compounds were
investigated in both skin and pulp tissues of seven apple accessions across the Malus
genus collected at two stages: during fruit development and at harvest. The primary difference
in phenolic concentration between wild and domesticated accessions, especially in the
pulp, could be explained by the larger growth rate of the domesticated varieties. The proposed
dilution effect was also confirmed through the observation of the increased content of
procyanidin B2+B4 and phloridzin in russet-skinned apples, known to have higher concentrations
of these compounds. The metabolite screening was also accompanied by the
expression analysis of 16 polyphenolic genes showing, for nine elements, a higher expression
at harvest than during fruit development. Finally, a polyphenolic comparison with redfleshed
apples was also carried out, underlying a larger amount of procyanidins and quercetin-
3rhamnoside in the white-fleshed accessions. The results presented and discussed in
this work suggest that specific white-fleshed apples, especially with russeted-skin, may play
an important role in ameliorating the nutraceutical potential of apple fruit
Is the physiological maturity at harvest influencing nectarine flavour after cold storage?
No full textPeach and nectarine are often harvested immature to withstand the postharvest
handling without considering the consequence on fruit quality and therefore
consumer’s satisfaction and their likelihood of repurchase. Indeed, the inaccurate
determination of the optimal harvest time leads to a considerable reduction in fruit
quality at consumption. Despite fruit volatile organic compounds (VOCs) being
positively associated with the consumer acceptance, VOCs are not well-considered in
the optimization of pre- and postharvest fruit management. The aim of this research
was to investigate the effect of fruit physiological maturity at harvest on the
development of VOCs during a simulated postharvest chain. Fruits of ‘Stark Red Gold’
nectarine, harvested at different maturity stages, determined by the “index of
absorbance difference” (IAD), were stored at 1°C (90-95% RH) for 20 days then
maintained 6 days in shelf-life at 20°C. The evolution in aroma production was
monitored in each day of shelf life by proton transfer reaction – time of flight – mass
spectrometry (PTR-ToF-MS). Besides the VOC measurement, fruit were assessed for
the main quality traits: soluble solids content, flesh firmness and titratable acidity.
Results of this research shows that the concentration of the main aroma compounds
such as lactones (mainly γ- and δ-decalactones) and esters (mainly methyl acetate)
increased during the progression of ripening while aldehydes (mainly pentanal) and
C6-aldehydes (predominantly hexanal and 3-hexenal) decreased. However the
concentration of these compounds, irrespective of the harvest maturity stages, was
significantly reduced after cold storage, indicating a negative effect of low
temperature in the development of aroma compounds. In addition fruit senescence
was clearly marked by an enhanced emission of off-flavour compounds, such as
ethanol, acetaldehyde and methanol
Electrical Characterization of minority carrier transport parameters in n-type heavily doped silicon
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