Cristina Besada

A Non-Targeted Approach Unravels the Volatile Network in Peach Fruit

Volatile compounds represent an important part of the plant metabolome and are of particular agronomic and biological interest due to their contribution to fruit aroma and flavor and therefore to fruit quality. By using a non-targeted approach based on HS-SPME-GC-MS, the volatile-compound complement of peach fruit was described. A total of 110 volatile compounds (including alcohols, ketones, aldehydes, esters, lactones, carboxylic acids, phenolics and terpenoids) were identified and quantified in peach fruit samples from different genetic backgrounds, locations, maturity stages and physiological responses. By using a combination of hierarchical cluster analysis and metabolomic correlation network analysis we found that previously known peach fruit volatiles are clustered according to their chemical nature or known biosynthetic pathways. Moreover, novel volatiles that had not yet been described in peach were identified and assigned to co-regulated groups. In addition, our analyses showed that most of the co-regulated groups showed good intergroup correlations that are therefore consistent with the existence of a higher level of regulation orchestrating volatile production under different conditions and/or developmental stages. In addition, this volatile network of interactions provides the ground information for future biochemical studies as well as a useful route map for breeding or biotechnological purposes.

Volatile compounds associated to the loss of astringency in persimmon fruit revealed by untargeted GC-MS analysis

High resolution volatile profiling (67 compounds identified) of fruits from 12 persimmon cultivars was established and used to characterize the different astringency types of persimmon fruit before and after deastringency treatment. Analysis of the volatile profile of fruit enables us to differentiate between cultivars that at the moment of harvest produced non-astringent fruit (Pollination Constant Non Astringent—PCNA-type) from astringent ones (non-PCNA-type). Fruit failing to accumulate astringent compounds naturally (PCNA fruit) showed high levels of 3(2H)-benzofuranone, while this compound was not detected in any astringent type fruit (non-PCNA). In addition to this, PCNA cultivars also showed at harvest higher accumulation of benzeneacetaldehyde and lipid-derived aldehydes (hexanal, heptanal, octanal and decanal) than non-PCNA fruit. The application of postharvest deastringency treatment to all non-PCNA cultivars resulted on an important insolubilization of tannins. In general the CO2-treatment enhanced the levels of acetaldehyde, however those cultivars showing high levels of dihydrobenzofuran at harvest did not present an increment of acetaldehyde. In contrast, all non-PCNA cultivars exhibited an important accumulation of lipid-derived aldehydes due to CO2-treatment. Therefore, we propose that lipid-derived aldehydes (mainly decanal, octanal and heptanal) may be playing a role in the astringency loss. Our results suggest that 3(2H)-benzofuranone, benzeneacetaldehyde and lipid-derived aldehydes could be used as markers for both natural and artificial loss of astringency.

A combination of physiological and chemometrics analyses reveals the main associations between quality and ripening traits and volatiles in two loquat cultivars

A combined analysis of physiological traits, volatile composition and sensory evaluation of aromatic quality was conducted on the ‘Algerie’ and ‘Golden Nuggett’ cultivars at six maturity stages, covering colour breaking to complete ripening. The main difference between cultivars during ripening was aromatic character; organoleptic differences between cultivars were assessed by a taste panel and could be explained by the volatile profile at harvest, and more specifically by those volatiles showing a rapid increase as fruits fully ripened. Among the 121 volatile compounds identified in loquat fruits, 2-methyl butanoic acid was the only cultivar-specific VOC, detected only in ‘Algerie’, while the levels of other common VOCs also contributed to differentiation between cultivars. A correlation analysis ran between volatile compounds levels and loquat aroma and flavour intensity revealed that 1,2-dimethoxy-4-(2-methoxyethenyl)benzene, elemicin, (Z)-2-hexen-1-ol, methyl 2-methylbutanoate, methyl 3,4,5-trimethoxybenzoate, cis-geranylacetone, (E)-methyl cinnamate, (E)-2-decenal, cis-edulan and 1-hydroxycyclohexyl phenyl ketone were volatiles which could importantly contribute to loquat’s aromatic character, some of which are reported here for the first time as key volatiles in aromatic quality. The correlations among the physiological parameters, the volatile compounds and physiological traits, and the parallelisms between precursors and volatile product, are discussed as they offer clues about loquat quality-associated metabolic changes during ripening.

Chloride stress triggers maturation and negatively affects the postharvest quality of persimmon fruit. Involvement of calyx ethylene production.

In recent years many hectares planted with persimmon trees in E Spain have been diagnosed with chloride toxicity. An effect of this abiotic stress on fruit quality has been reported in different crops. However, the impact of chloride stress on persimmon fruit quality is unknown. The harvest and postharvest quality of persimmons harvested from trees that manifest different intensities of chloride toxicity foliar symptoms was evaluated herein. Our results revealed that fruits from trees under chloride stress conditions underwent chloride accumulation in the calyx, which was more marked the greater the salt stress intensity trees were exposed to. Increased chloride concentrations in the calyx stimulated ethylene production in this tissue. In the fruits affected by slight and moderate chloride stress, calyx ethylene production accelerated the maturity process, as reflected by increased fruit colour and diminished fruit firmness. In the fruits under severe chloride stress, the high ethylene levels in the calyx triggered autocatalytic ethylene production in other fruit tissues, which led fruit maturity to drastically advance. In these fruits effectiveness of CO2 deastringency treatment was not complete and fruit softening enhanced during the postharvest period. Moreover, chloride stress conditions had a marked effect on reducing fruit weight, even in slightly stressed trees.

A WD40-repeat protein from persimmon interacts with the regulators of proanthocyanidin biosynthesis DkMYB2 and DkMYB4

MYB-bHLH-WD40 (MBW) ternary complexes composed of MYB domain proteins, basic helix-loop-helix (bHLH) transcription factors and WD40-repeat proteins are involved in the transcriptional regulation of anthocyanin and proanthocyanidin (PA) biosynthesis pathways in distinct plant species. PAs are the compounds responsible for the strong astringent taste of persimmon fruit. DkMYB2 and DkMYB4 (MYB type) and DkMYC1 (bHLH type) genes from persimmon have been postulated to regulate the biosynthesis of PAs in fruit. We have identified a WD40-repeat gene from persimmon (DkWDR1) coding for a protein highly similar to TTG1 from Arabidopsis thaliana and other WD40-repeat components of distinct MBW complexes. DkWDR1 expression was detected in different tissues and was essentially constant during fruit development. MYB-like proteins DkMYB2 and DkMYB4 interacted with both DkWDR1 and DkMYC1 in the yeast two-hybrid system. The sequence of DkWDR1 and the analysis of yeast two-hybrid interactions with known regulators of PA biosynthesis support the occurrence of MYB-bHLH-WD40 (MBW) complexes in persimmon, to regulate PA accumulation in fruit.

Postharvest Biology and Technology of Persimmon

Persimmon production has continued to increase in recent years. It is now being cultivated in more countries and new varieties are also reaching markets. One important feature that differentiates persimmon from other fruit crops is that the fruits from some cultivars are astringent at harvest, while other cultivars produce non-astringent fruits. Therefore, from a postharvest point of view, some cultivars require specific treatments being applied to remove astringency before their commercialization. On the other hand, storage of persimmons is limited by their sensitivity to manifest chilling injury at low temperature; the main chilling injury symptoms are related to textural changes. This chapter presents the postharvest biology and technology aspects of persimmon fruits.

Persimmon (Diospyros kaki) Trees Responses to Restrictions in Water Amount and Quality

Abstract Persimmon cultivation is gaining importance in many semiarid areas of the world. In this chapter, existing information in the literature on persimmon water requirements and responses to variations in water supply and quality are summarized. It is concluded that persimmon water needs can be particularly high during summer, when the crop coefficient can reach values close to or even above 1.0. To cope with water scarcity, regulated deficit irrigation (RDI) has been shown as a useful technique for reducing fruit drop in persimmon trees. Late RDI strategies during fruit ripening can accelerate fruit color development resulting in earlier harvesting but with lower fruit weight. This chapter also provides important information on persimmon tree responses to salinity, along with methods to alleviate the detrimental impacts of low-quality irrigation waters on tree performance.