Assessment and Classification of Volatile Profiles in Melon Breeding Lines Using Headspace Solid-Phase Microextraction Coupled with Gas Chromatography-Mass Spectrometry

A matter of smell: The complex regulation of aroma production in melon

Melon fruit flavor is one of the most valuable traits for consumers. Aroma, formed by volatile organic compounds (VOCs), is a major component of flavor but has been neglected in breeding programs because of its complex regulation. Although the genetic regulation of VOCs biosynthesis is not fully understood, several advances have been recently achieved. VOCs originate from the degradation of fatty acids, aminoacids and terpenes, and the role of newly described enzymes, transcription factors and putative regulators is here discussed. Furthermore, ethylene plays a key role in fruit aroma production in melon, triggering the conversion of green-flavored aldehydes into fruity-flavored esters. A current challenge is to understand the ethylene-independent regulation of VOCs formation. Environmental conditions and human processing can also shape the melon volatile profile, and future research should focus on studying the effect of climate change in aroma formation.

Evaluation of Aromatic Characteristics and Potential Applications of Hemerocallis L. Based on the Analytic Hierarchy Process

Hemerocallis L. possesses abundant germplasm resources and holds significant value in terms of ornamental, edible, and medicinal aspects. However, the quality characteristics vary significantly depending on different varieties. Selection of a high-quality variety with a characteristic aroma can increase the economic value of Hemerocallis flowers. The analytic hierarchy process (AHP) is an effective decision-making method for comparing and evaluating multiple characteristic dimensions. By applying AHP, the aromatic character of 60 varieties of Hemerocallis flowers were analyzed and evaluated in the present study. Headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) was employed to identify volatile components in Hemerocallis flowers. Thirteen volatile components were found to contribute to the aroma of Hemerocallis flowers, which helps in assessing their potential applications in essential oil, aromatherapy, and medical treatment. These components include 2-phenylethanol, geraniol, linalool, nonanal, decanal, (E)-β-ocimene, α-farnesene, indole, nerolidol, 3-furanmethanol, 3-carene, benzaldehyde and benzenemethanol. The varieties with better aromatic potential can be selected from a large amount of data using an AHP model. This study provides a comprehensive understanding of the characteristics of the aroma components in Hemerocallis flowers, offers guidance for breeding, and enhances the economic value of Hemerocallis flowers.

Regulation of climacteric fruit ripening in melon: recent advances and future challenges

Fruit ripening is a complex and highly regulated process where tomato and strawberry have been the model species classically used for studying climacteric and non-climacteric fleshy fruit ripening types, respectively. Melon has emerged as an alternative ripening model because climacteric and non-climacteric cultivars exist, which makes it possible to dissect the regulation of ripening using a genetic approach. Several quantitative trait loci that regulate climacteric fruit ripening have been identified to date, and their combination in both climacteric and non-climacteric genetic backgrounds resulted in lines with different ripening behaviors, demonstrating that the climacteric intensity can be genetically modulated. This review discusses our current knowledge of the physiological changes observed during melon climacteric fruit ripening such as ethylene production, fruit abscission, chlorophyll degradation, firmness, and aroma, as well as their complex genetic control. From pioneer experiments in which ethylene biosynthesis was silenced, to the recent genetic edition of ripening regulators, current data suggest that the climacteric response is determined by the interaction of several loci under quantitative inheritance. The exploitation of the rich genetic diversity of melon will enable the discovery of additional genes involved in the regulation of the climacteric response, ultimately leading to breeding aromatic melon fruits with extended shelf life.

Herbivore-Dependent Induced Volatiles in Pear Plants Cause Differential Attractive Response by Lacewing Larvae

Biological control may benefit from the behavioral manipulation of natural enemies using volatile organic compounds (VOCs). Among these, herbivore-induced plant volatiles (HIPVs) provide potential tools for attracting or retaining predators and parasitoids of insect pests. This work aimed to characterize the VOCs emitted by pear plants in response to attack by Cacopsylla bidens (Hemiptera: Psyllidae), a major pest in pear orchards, to compare these with VOCs induced by a leaf chewing insect, Argyrotaenia sphaleropa (Lepidoptera: Tortricidae), and to evaluate the behavioral response of Chrysoperla externa (Neuroptera: Chrysopidae) to HIPVs from pear plants damaged by either herbivore. The results demonstrated that plants damaged by the pear psylla emitted VOC blends with increased amounts of aliphatic aldehydes. Leafroller damage resulted in increased amounts of benzeneacetonitrile, (E)-4,8-dimethylnona-1,3,7-triene, β-ocimene and caryophyllene. In olfactometer bioassays, larvae of C. externa were attracted to herbivore-damaged plants when contrasted with undamaged plants. When plant odors from psylla-damaged were contrasted with those of leafroller-damaged plants, C.externa preferred the former, also showing shorter response lag-times and higher response rates when psylla-damaged plants were present. Our results suggest that pear plants respond to herbivory by modifying their volatile profile, and that psylla-induced volatiles may be used as prey-specific chemical cues by chrysopid larvae. Our study is the first to report HIPVs in pear plants attacked by C. bidens, as well as the attraction of C. externa to psyllid-induced volatiles.

The transcription factor CmERFI-2 represses CmMYB44 expression to increase sucrose levels in oriental melon fruit

Soluble sugar accumulation in fruit ripening determines fleshy fruit quality. However, the molecular mechanism for this process is not yet understood. Here, we showed a transcriptional repressor, CmMYB44 regulates sucrose accumulation and ethylene synthesis in oriental melon (Cucumis. melo var. makuwa Makino) fruit. Overexpressing CmMYB44 suppressed sucrose accumulation and ethylene production. Furthermore, CmMYB44 repressed the transcriptional activation of CmSPS1 (sucrose phosphate synthase 1) and CmACO1 (ACC oxidase 1), two key genes in sucrose and ethylene accumulation, respectively. During the later stages of fruit ripening, the repressive effect of CmMYB44 on CmSPS1 and CmACO1 could be released by overexpressing CmERFI-2 (ethylene response factor I-2) and exogenous ethylene in "HS" fruit (high sucrose accumulation fruit). CmERFI-2 acted upstream of CmMYB44 as a repressor by directly binding the CmMYB44 promoter region, indirectly stimulating the expression level of CmSPS1 and CmACO1. Taken together, we provided a molecular regulatory pathway mediated by CmMYB44, which determines the degree of sucrose and ethylene accumulation in oriental melon fruit and sheds light on transcriptional responses triggered by ethylene sensing that enable the process of fruit ripening.

Effects of musk volatile compounds on attenuated nerve injury and improving post-cerebral ischemic exercise functions

BACKGROUND

Reperfusion Injury Acute ischemic stroke is increasing in people recently and Musk, as a commonly used Traditional Chinese Medicine (TCM), has been suggested as a potential agent against acute ischemic stroke, but the efficacies and underlying mechanisms of it remain unknown.

OBJECTIVE

This study was aimed to tested the hypotheses that volatile compounds of musk could attenuate nerve injury and identify the bioactive compounds and potential mechanisms of Musk.

METHOD

Transient middle cerebral artery occlusion (MCAO) model in vivo in Sprague-Dawley rats (SD rats) was used to test this hypothesis. Collecting ingredients of Musk and their related targets were discerned from the Gas chromatography-olfactory mass spectrometry (GC-O-MS) experiment. Then the potential mechanisms and targets of the compounds were searched by network pharmacology techniques. Finally, the pathway was verified by Western Bolt (WB).

RESULTS

First, Musk treatment significantly up-regulated the relative levels of AKT1, PI3KA, and VEGFA in the hippocampus, and improved the sport functions in the post-MCAO ischemic rats in vivo. Next, twenty potential flavor active compounds were recognized by GC-O-MS. A total of 89 key targets including HIF-1, PIK3CA, TNF signaling pathway, and VEGF were identified. AKT1, HIF1A, PIK3CA, and VEGFA were viewed as the most important genes, which were validated by molecular docking simulation.

CONCLUSION

The Volatile compounds of musk can attenuate nerve injury and improving post-cerebral ischemic exercise functions by HIF1A pathways, and the combined data provide novel insight for Musk volatile compounds developed as new drug for improving reperfusion injury in acute ischemic stroke.

R. Rocha C, Teixeira JA, Pereira JAM. Green Extraction Techniques as Advanced Sample Preparation Approaches in Biological, Food, and Environmental Matrices: A Review

Green extraction techniques (GreETs) emerged in the last decade as greener and sustainable alternatives to classical sample preparation procedures aiming to improve the selectivity and sensitivity of analytical methods, simultaneously reducing the deleterious side effects of classical extraction techniques (CETs) for both the operator and the environment. The implementation of improved processes that overcome the main constraints of classical methods in terms of efficiency and ability to minimize or eliminate the use and generation of harmful substances will promote more efficient use of energy and resources in close association with the principles supporting the concept of green chemistry. The current review aims to update the state of the art of some cutting-edge GreETs developed and implemented in recent years focusing on the improvement of the main analytical features, practical aspects, and relevant applications in the biological, food, and environmental fields. Approaches to improve and accelerate the extraction efficiency and to lower solvent consumption, including sorbent-based techniques, such as solid-phase microextraction (SPME) and fabric-phase sorbent extraction (FPSE), and solvent-based techniques (μQuEChERS; micro quick, easy, cheap, effective, rugged, and safe), ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE), in addition to supercritical fluid extraction (SFE) and pressurized solvent extraction (PSE), are highlighted.