Preassigned-time projective synchronization of delayed fully quaternion-valued discontinuous neural networks with parameter uncertainties.

This paper concerns with the preassigned-time projective synchronization issue for delayed fully quaternion-valued discontinuous neural networks involving parameter uncertainties through the non-separation method. Above all, based on the existing works, a new preassigned-time stability theorem is established. Subsequently, to realize the control goals, two types of novel and simple chattering-free quaternion controllers are designed, one without the power-law term and the other with a hyperbolic-tangent function. They are different from the existing common power-law controller and exponential controller. Thirdly, under the Filippov discontinuity theories and with the aid of quaternion inequality techniques, some novel succinct sufficient criteria are obtained to ensure the addressed systems to achieve the preassigned-time synchronization by using the preassigned-time stability theory. The preassigned settling time is free from any parameter and any initial value of the system, and can be preset according to the actual task demands. Particularly, unlike the existing results, the proposed control methods can effectively avoid the chattering phenomenon, and the time delay part is removed for simplicity. Additionally, the projection coefficient is generic quaternion-valued instead of real-valued or complex-valued, and some of the previous relevant results are extended. Lastly, numerical simulations are reported to substantiate the effectiveness of the control strategies, the merits of preassigned settling time, and the correctness of the acquired results.

Prediction Model of hospitalization time of COVID-19 patients based on Gradient Boosted Regression Trees.

When an outbreak of COVID-19 occurs, it will cause a shortage of medical resources and the surge of demand for hospital beds. Predicting the length of stay (LOS) of COVID-19 patients is helpful to the overall coordination of hospital management and improves the utilization rate of medical resources. The purpose of this paper is to predict LOS for patients with COVID-19, so as to provide hospital management with auxiliary decision-making of medical resource scheduling. We collected the data of 166 COVID-19 patients in a hospital in Xinjiang from July 19, 2020, to August 26, 2020, and carried out a retrospective study. The results showed that the median LOS was 17.0 days, and the average of LOS was 18.06 days. Demographic data and clinical indicators were included as predictive variables to construct a model for predicting the LOS using gradient boosted regression trees (GBRT). The MSE, MAE and MAPE of the model are 23.84, 4.12 and 0.76 respectively. The importance of all the variables involved in the prediction of the model was analyzed, and the clinical indexes creatine kinase-MB (CK-MB), C-reactive protein (CRP), creatine kinase (CK), white blood cell count (WBC) and the age of patients had a higher contribution to the LOS. We found our GBRT model can accurately predict the LOS of COVID-19 patients, which will provide good assistant decision-making for medical management.

Spatial age-period-cohort analysis of hepatitis B risk in Xinjiang from 2006 to 2019.

Objective: The objective of this study was to investigate the spatio-temporal distribution and epidemiological characteristics of hepatitis B in 96 districts and counties of Xinjiang and to give useful information for hepatitis B prevention and treatment. Methods: Based on the incidence data of hepatitis B in 96 districts and counties of Xinjiang from 2006 to 2019, the global trend analysis method was used to characterize the spatial variability of the disease, and the spatial autocorrelation and spatio-temporal aggregation analysis were used to explore the spatial clustering of hepatitis B and to identify high-risk areas and periods. The Integrated Nested Laplace Approximation (INLA)-based spatial age-period-cohort model was established to further explore the influence of age, period, birth queue effect, and spatial distribution on the incidence risk of hepatitis B, and sum-to-zero constraint was adopted to avoid the issue of model unrecognition. Results: The risk of hepatitis B in Xinjiang is increasing from west to east and from north to south, with spatial heterogeneity and spatio-temporal scanning statistics yielding five clustering areas. The spatial age-period-cohort model showed two peaks in the average risk of hepatitis B, at [25,30) years old and [50,55) years old, respectively. The mean risk of hepatitis B incidence fluctuated up and down around 1 with time, and the average risk of disease by birth cohort displayed an increasing-decreasing-stabilizing trend. Taking age, period, and cohort effect into consideration, it was found that the areas with a high risk of hepatitis B are Tianshan District, Xinshi District, Shuimogou District, Changji City, Aksu City, Kashi City, Korla City, Qiemo County and Yopurga County in Xinjiang. According to the spatio-temporal effect item, it was found that there are unobserved variables affecting the incidence of hepatitis B in some districts and counties of Xinjiang. Conclusion: The spatio-temporal characteristics of hepatitis B and the high-risk population needed to be taken into attention. It is suggested that the relevant disease prevention and control centers should strengthen the prevention and control of hepatitis B among young people while paying attention to middle-aged and older adult people, and strengthening the prevention and monitoring of high-risk areas.

Autophagy in protists and their hosts: When, how and why?

Pathogenic protists are a group of organisms responsible for causing a variety of human diseases including malaria, sleeping sickness, Chagas disease, leishmaniasis, and toxoplasmosis, among others. These diseases, which affect more than one billion people globally, mainly the poorest populations, are characterized by severe chronic stages and the lack of effective antiparasitic treatment. Parasitic protists display complex life-cycles and go through different cellular transformations in order to adapt to the different hosts they live in. Autophagy, a highly conserved cellular degradation process, has emerged as a key mechanism required for these differentiation processes, as well as other functions that are crucial to parasite fitness. In contrast to yeasts and mammals, protist autophagy is characterized by a modest number of conserved autophagy-related proteins (ATGs) that, even though, can drive the autophagosome formation and degradation. In addition, during their intracellular cycle, the interaction of these pathogens with the host autophagy system plays a crucial role resulting in a beneficial or harmful effect that is important for the outcome of the infection. In this review, we summarize the current state of knowledge on autophagy and other related mechanisms in pathogenic protists and their hosts. We sought to emphasize when, how, and why this process takes place, and the effects it may have on the parasitic cycle. A better understanding of the significance of autophagy for the protist life-cycle will potentially be helpful to design novel anti-parasitic strategies.

Molecular phylogenetics and diversity of the Himalayan shrew ( Soriculus nigrescens Gray, 1842) (Eulipotyphla, Soricidae) in Southwest China.

The Himalayan shrew, Soriculus nigrescens Gray, 1842, belongs to the monotypic genus Soriculus, which is distributed mainly in the Himalayan region. Previous authors have studied its classification based on morphological and molecular data. However, no comprehensive study of the diversity and phylogeny of this species has been performed. In this study, we investigated the molecular phylogeny, genetic diversity, and species divergence of S. nigrescens based on one mitochondrial gene and three nuclear genes. A total of 124 samples from 27 sites in Southwest China were analyzed. Our molecular phylogenetic analyses and species divergence reveal non-monophyly of Soriculus, potentially representing two genera and three clades. Populations from Yunnan (Clade YN) represent the subspecies S. n. minors and should recover the full species status. Populations from Himalayas (Clade A) represent the species S. nigrescens, while populations from southeastern Nyenchen Tanglha Mountains and southern Himalayas (Clade B) represent a new cryptic and unnamed species. Species delimitation analyses and deep genetic distance analysis clearly support the species status of these three evolving clades. The putative new genus and cryptic species should be studied and identified in the future using a more extensive sampling combined with a comprehensive morphological and phylogenetic analysis.

Fixed-time projective synchronization of delayed memristive neural networks via aperiodically semi-intermittent switching control.

This paper studies the fixed-time projective synchronization problem for a class of delayed memristive neural networks via aperiodically semi-intermittent switching control. Instead of using the common traditional controller containing two power exponent terms, a novel aperiodically semi-intermittent switching controller is designed, containing only one power exponent term which serves as a function of the state of the error system. With the aid of the extended differential inclusion framework, the analysis method, and the inequality technique, some new sufficient conditions are derived to guarantee fixed-time projective synchronization for the considered systems. Compared with periodically semi-intermittent control methods, the control time width of each section in aperiodically semi-intermittent control can be adjusted. Especially, the settling time is directly reckoned, which is closely related to the number of neurons and the maximum ratio of the second subinterval span in each non-periodic span to all non-periodic time spans rather than the initial value. Additionally, the projection synchronization has a strong practicality, as the projection coefficient can be adjusted for different needs instead of being fixed. Meanwhile, the study improves some previous related works. Ultimately, a numerical example is given to substantiate the correctness of the obtained results.

A NAC transcriptional factor BrNAC029 is involved in cytokinin-delayed leaf senescence in postharvest Chinese flowering cabbage.

Both cytokinin and NAC transcription factors were reported to involve in leaf senescence. However, the mechanism of NAC transcription factors how to regulate cytokinin-delayed leaf senescence is still unknown. In this study, application of N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU), a cytokinin analogue, significantly delayed leaf senescence and maintained cytokinin content of Chinese flowering cabbage during storage. Meanwhile, the expression of an NAC transcriptional activator (BrNAC029) was increased but suppressed by CPPU treatment. Furthermore, BrNAC029 activated the expressions of chlorophyll catabolic genes BrPAO and BrSGR2, cytokinin oxidase gene BrCKX1 and senescence maker gene BrSAG113 by binding to their promoters. Additionally, overexpressions of BrNAC029 in tobacco and Arabidopsis accelerated leaf senescence and up-expressed the related genes. Taken together, it was suggested that BrNAC029 may serve as a transcriptional activator to activate the transcriptions of these related genes to eventually accelerate leaf senescence of Chinese flowering cabbage by promoting chlorophyll degradation and reducing endogenous cytokinin level.

Chromosome-level Genome Assembly of the High-altitude Leopard (Panthera pardus) Sheds Light on Its Environmental Adaptation.

The leopard (Panthera pardus) has the largest natural distribution from low- to high-altitude areas of any wild felid species, but recent studies have revealed that leopards have disappeared from large areas, probably owing to poaching, a decline of prey species, and habitat degradation. Here, we reported the chromosome-scale genome assembly of the high-altitude leopard (HL) based on nanopore sequencing and high-throughput chromatin conformation capture (Hi-C) technology. Panthera genomes revealed similar repeat composition, and there was an appreciably conserved synteny between HL and the other two Panthera genomes. Divergence time analysis based on the whole genomes revealed that the HL and the low-altitude leopard differentiate from a common ancestor ∼2.2 Ma. Through comparative genomics analyses, we found molecular genetic signatures that may reflect high-altitude adaptation of the HL. Three HL-specific missense mutations were detected in two positively selected genes, that is, ITGA7 (Ala112Gly, Asp113Val, and Gln115Pro) and NOTCH2 (Ala2398Ser), which are likely to be associated with hypoxia adaptation. The chromosome-level genome of the HL provides valuable resources for the investigation of high-altitude adaptation and protection management of the vulnerable leopard.

Genomics and morphometrics reveal the adaptive evolution of pikas.

Pikas (Lagomorpha: Ochotonidae) are small mouse-like lagomorphs. To investigate their adaptation to different ecological environments during their dispersal from the Qinghai-Xizang (Tibet) Plateau (QTP), we collected 226 pikas and measured 20 morphological characteristics and recorded habitat information. We also sequenced the genome of 81 specimens, representing 27 putative pika species. The genome-wide tree based on 4 090 coding genes identified five subgenera, i.e., Alienauroa, Conothoa, Lagotona, Ochotona, and Pika, consistent with morphometric data. Morphologically, Alienauroa and Ochotona had similar traits, including smaller size and earlier divergence time compared to other pikas. Consistently, the habitats of Alienauroa and Ochotona differed from those of the remaining subgenera. Phylogenetic signal analysis detected 83 genes significantly related to morphological characteristics, including several visual and hearing-related genes. Analysis of shared amino acid substitutions and positively selected genes (PSGs) in Alienauroa and Ochotona identified two genes, i.e., mitochondrial function-related TSFM (p.Q155E) and low-light visual sensitivity-related PROM1 (p.H419Y). Functional experiments demonstrated that TSFM-155E significantly enhanced mitochondrial function compared to TSFM-155Q in other pikas, and PROM1-419Y decreased the modeling of dynamic intracellular chloride efflux upon calcium uptake. Alienauroa and Ochotona individuals mostly inhabit different environments (e.g., subtropical forests) than other pikas, suggesting that a shift from the larger ancestral type and changes in sensory acuity and energy enhancement may have been required in their new environments. This study increases our understanding of the evolutionary history of pikas.

Improved genome assembly provides new insights into the environmental adaptation of the American cockroach, Periplaneta americana.

The synanthropic pest and a model organism for entomological research, American cockroach, Periplaneta americana (Linnaeus), can survive in unfavorable environments for humans. To investigate the genetic mechanisms of success in environmental adaptation of P. americana, we de novo reassembled its whole genome based on next-generation sequencing and PacBio sequencing. The final genome reassembly consisted of approximately 3.34 Gb with scaffold N50 of 465.51 Kb. The completeness (95.4%) of the complete genome was evaluated with single-copy orthologous genes using BUSCO. We identified 18,618 protein-coding genes, 16,443 (88.32%) of which were well supported by public protein databases. We identified 482.04 Mb (approximately 14.45%) repeat elements, 1,385,093 perfect microsatellites simple sequence repeats in P. americana genome, which was higher than other four Blattaria insects. Comparative genomics analysis revealed obvious expansion in the gene families associated with chemoreception (olfactory receptors, gustatory receptors, ionotropic glutamate receptors, chemosensory protein, and sensory neuron membrane protein), which provided the necessary information for functional characterization of the chemosensory receptors of P. americana, with potential for new or refined applications of semiochemicals-based control of this pest insect. Similarly, gene families (cytochrome P450s, carboxyl/choline esterases, and UDP-glycosyl-transferases) encoding receptors for bitter or toxic substances and detoxification enzymes were obviously expanded in P. americana, enabling its ability to detect and detoxify many toxins. Enrichment analysis of positively selected genes in P. americana revealed items associated with metabolic process and catalytic activity, which possibly contributed to the pesticide resistance of P. americana. We also analyzed the homologs to antimicrobial peptide genes reported in the Drosophila genome, and identified two attacins and seven defensins in P. americana. Our data and findings will substantially facilitate molecular studies in P. americana, including elucidation of detoxification mechanisms of xenobiotic, as well as development of new pest management strategies for the control of pests like P. americana.

Multi-locus phylogeny and species delimitations of the striped-back shrew group (Eulipotyphla: Soricidae): Implications for cryptic diversity, taxonomy and multiple speciation patterns.

The striped-back shrew group demonstrates remarkable variation in skull and body size, tail length, and brightness of the dorsal stripe; and karyotypic and DNA variation has been reported in recent years. In this study, we investigated the phylogenetic structure of the group, as well as speciation patterns and demographic history in Mountains of Southwestern China and adjacent mountains, including the southern Himalayas, Mts. Bashan, Wushan, and Qinling. We sequenced a total of 462 specimens from 126 localities in the known range of the group, which were sequenced and analyzed based on 6.2 kb of sequence data from two mitochondrial, six nuclear, and two Y chromosome markers. Phylogenetic analyses of the concatenated mtDNA data revealed 14 sympatric and independently evolving lineages within the striped-back shrew group, including Sorex bedfordiae, S. cylindricauda, S. excelsus, S. sinalis and several cryptic species. All concatenated data (ten genes) showed a consistent genetic structure compared to the mtDNA lineages for the group, whereas the nuclear and the Y chromosome data showed a discordant genetic structure compared to the mtDNA lineages for the striped-back shrew group. Species delimitation analyses and deep genetic distance clearly support the species status of the 14 evolving lineages. The divergence time estimation suggested that the striped-back shrew group began to diversify from the middle Pleistocene (2.34 Ma), then flourished at approximately 2.14 Ma, followed by a series of rapid diversifications through the Pleistocene. Our results also revealed multiple mechanisms of speciation in the Mountains of Southwestern China and Adjacent Mountains with complex landscapes and climate. The uplifting of the Qinghai-Tibetan Plateau, Quaternary climate oscillations, riverine barriers, ecological elevation gradients, topographical diversity, and their own low dispersal capacity may have driven the speciation, genetic structure, and phylogeographic patterns of the striped-back shrew group.

Perfect diffractive circular metagrating for Bessel beam transformation.

Bessel beams, with their non-diffractive property, have attracted great interest in recent years. Optical needle shaping of Bessel beams is highly desired in many applications, however, this typically requires low numerical aperture (NA) bulky 4f confocal systems incorporated with spatial light modulators or round filters. Here, we employ a circular dielectric metagrating for perfect Bessel beam transformation at a desired wavelength. The dielectric metagrating exhibits a high transmissive diffraction efficiency (up to 75%) for a broadband (460 nm to 560 nm), wide-angle range, and dual-polarization response, which is capable of a high-performance transformation of Bessel beams with arbitrary NAs. Our results show potential for special-beam-required applications such as light storage, imaging, and optical manipulation.

Finite-/fixed-time synchronization for Cohen-Grossberg neural networks with discontinuous or continuous activations via periodically switching control.

This paper is concerned with finite-/fixed-time synchronization for a class of Cohen-Grossberg neural networks with discontinuous or continuous activations and mixed time delays. Based on the finite-time stability theory, Lyapunov stability theory, the concept of Filippov solution and the differential inclusion theory, some useful finite-/fixed-time synchronization sufficient conditions for the considered Cohen-Grossberg neural networks are established by designing two kinds of novel periodically switching controllers. Instead of using uninterrupted high control strength, the periodically switching controller in each period is used with high strength control in one stage and weak strength in the other. It can overcome the effects caused by the uncertainties of Filippov solution induced by discontinuous neuron activation functions and reduce the control cost. Besides, the period switching control rate is closely related to the settling time T. Finally, two numerical examples are given to demonstrate the effectiveness and feasibility of the obtained results.

Comparative metagenomics analysis reveals how the diet shapes the gut microbiota in several small mammals.

The gut microbiomes of the host are large and complex communities, which helps to maintain homeostasis, improves digestive efficiency, and promotes the development of the immune system. The small mammals distributed in Sichuan Province are the most popular species for biodiversity research in Southwest China. However, the effects of different diets on the structure and function of the gut microbial community of these small mammals are poorly understood. In this study, whole-metagenome shotgun sequencing has been used to analyze the composition and functional structures of the gut microbiota of seven small mammals in Laojunshan National Nature Reserve, Sichuan Province, China. Taxonomic classification revealed that the most abundant phyla in the gut of seven small mammals were Bacteroides, Proteobacteria, and Firmicutes. Moreover, Hafnia, Lactobacillus, and Yersinia were the most abundant genus in the gut microbiomes of these seven species. At the functional level, we annotated a series of KEGG functional pathways, six Cazy categories, and 46,163 AROs in the gut microbiomes of the seven species. Comparative analysis found that the difference in the gut microbiomes between the Soricidea and Muridae concentrated on the increase in the F/B (Firmicutes/Bacteroides) ratio in the Soricidea group, probably driven by the high-fat and -calorie digestive requirements due to their insectivorous diet. The comparative functional profiling revealed that functions related to metabolism and carbohydrates were significantly more abundant in Muridae group, which may be attributed to their high carbohydrate digestion requirements caused by their herbivorous diet. These data suggested that different diets in the host may play an important role in shaping the gut microbiota, and lay the foundation for teasing apart the influences of heritable and environmental factors on the evolution of gut microbial communities.

Comparative profiles of the cuticular chemicals and transpiration barrier properties in various organs of Chinese flowering cabbage and Chinese kale.

Plant cuticle as hydrophobic barrier covers almost all aerial plant organs. Herein the cuticular chemical components and the transpiration of various organs of Chinese flowering cabbage (CFC) and Chinese kale (CK) were comprehensively characterized. Numerous species- and organ-specific differences in morphological, chemical, and physiological levels were found. The various organs were relatively smooth in surface for CFC but glaucous with hollow tube- and plate-type crystals for CK. The chemical composition of cuticular waxes were very-long chain n-alkanes, ketones, secondary alcohols with a prominent carbon chain of C29 in CK, primary alcohols dominated by C26 , and aldehydes prominently C30 in CFC. Cutin monomers accumulated with similar levels as waxes and were dominated by α,ω-dicarboxylic acids and fatty acids without added groups. The minimum water conductance differed considerably among species and various organs ranging between 8.9 × 10-5 (CK leaf) and 3.7 × 10-4  m s-1 (CFC leaf petiole). These differences in transpiration properties were proposed to be largely related to the cuticular chemicals in various organs and species. The presented results provide further insights to link the transpiration barrier functions with surface characteristics and cuticular chemicals.

Cystoisospora belli infection in an AIDS patient in China: Need for cautious interpretation of mNGS.

Cystoisospora belli (C. belli) is an opportunistic coccidian parasite. This case is the first reported C. belli infection associated with AIDS in China. C. belli infection of this case was diagnosed with the presence of oocysts using direct wet mount and Ziehl-Neelsen acid-fast stain method, and confirmed by polymerase chain reaction (PCR) and Sanger sequencing, ruling out the result of metagenomic next-generation sequencing (mNGS). This case demonstrates that C. belli infection in AIDS could be a potential risk factor for persistent diarrhea, and should not be neglected in non-endemic area and emphaise the necessity of accurate mNGS databases.

Characterisation of novel functionality within the Blastocystis tryptophanase gene.

In recent years, the human gut microbiome has been recognised to play a pivotal role in the health of the host. Intestinal homeostasis relies on this intricate and complex relationship between the gut microbiota and the human host. While much effort and attention has been placed on the characterization of the organisms that inhabit the gut microbiome, the complex molecular cross-talk between the microbiota could also exert an effect on gastrointestinal conditions. Blastocystis is a single-cell eukaryotic parasite of emerging interest, as its beneficial or pathogenic role in the microbiota has been a subject of contention even to-date. In this study, we assessed the function of the Blastocystis tryptophanase gene (BhTnaA), which was acquired by horizontal gene transfer and likely to be of bacterial origin within Blastocystis. Bioinformatic analysis and phylogenetic reconstruction revealed distinct divergence of BhTnaA versus known bacterial homologs. Despite sharing high homology with the E. coli tryptophanase gene, we show that Blastocystis does not readily convert tryptophan into indole. Instead, BhTnaA preferentially catalyzes the conversion of indole to tryptophan. We also show a direct link between E. coli and Blastocystis tryptophan metabolism: In the presence of E. coli, Blastocystis ST7 is less able to metabolise indole to tryptophan. This study examines the potential for functional variation in horizontally-acquired genes relative to their canonical counterparts, and identifies Blastocystis as a possible producer of tryptophan within the gut.

BTH Treatment Delays the Senescence of Postharvest Pitaya Fruit in Relation to Enhancing Antioxidant System and Phenylpropanoid Pathway.

The plant resistance elicitor Benzo (1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) can enhance disease resistance of harvested fruit. Nonetheless, it is still unknown whether BTH plays a role in regulating fruit senescence. In this study, exogenous BTH treatment efficiently delayed the senescence of postharvest pitaya fruit with lower lipid peroxidation level. Furthermore, BTH-treated fruit exhibited lower hydrogen peroxide (H2O2) content, higher contents of reduced ascorbic acid (AsA) and reduced glutathione (GSH) levels and higher ratios of reduced to oxidized glutathione (GSH/GSSG) and ascorbic acid (AsA/DHA), as well as higher activities of ROS scavenging enzymes, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD) and glutathione reductase (GR) in comparison with control fruit. Moreover, BTH treatment enhanced the activities of phenylpropanoid pathway-related enzymes, including cinnamate-4-hydroxylase (C4H), phenylalanine ammonia-lyase (PAL) and 4-coumarate/coenzyme A ligase (4CL) and the levels of phenolics, flavonoids and lignin. In addition, BTH treatment upregulated the expression of HuSOD1/3/4, HuCAT2, HuAPX1/2 and HuPOD1/2/4 genes. These results suggested that application of BTH delayed the senescence of harvested pitaya fruit in relation to enhanced antioxidant system and phenylpropanoid pathway.

Salt-inducible kinase inhibition sensitizes human acute myeloid leukemia cells to all-trans retinoic acid-induced differentiation.

Differentiation therapies with all-trans retinoic acid (ATRA) have been successful in treating acute promyelocytic leukemia, a rare subtype of acute myeloid leukemia (AML). However, their efficacy is limited in the case of other AML subtypes. Here, we show that the combination of ATRA with salt-inducible kinase (SIK) inhibition significantly enhances ATRA-mediated AML differentiation. SIK inhibition augmented the ability of ATRA to induce growth inhibition and G1 cell cycle arrest of AML cells. Moreover, combining ATRA and SIK inhibition synergistically activated the Akt signaling pathway but not the MAPK pathway. Pharmacological blockade of Akt activity suppressed the combination-induced differentiation, indicating an essential role for Akt in the action of the combination treatment. Taken together, our study reveals a novel role for SIK in the regulation of ATRA-mediated AML differentiation, implicating the combination of ATRA and SIK inhibition as a promising approach for future differentiation therapy.

Chemical composition of the cuticular membrane in guava fruit (Psidium guajava L.) affects barrier property to transpiration.

The cuticular membrane covering almost all aerial plant organs has a primary function in limiting uncontrolled water loss. The guava fruits were collected and this work was done to study the potential contribution of cuticular chemical composition to fruit transpiration after harvest. The detailed cuticular chemical composition, based on gas chromatography together with mass spectrometry, and the transpiration rate determined gravimetrically in guava fruit were characterized in the present study. The predominant wax mixtures were fatty acids and primary alcohols with homologous series of C16-C33, as well as various pentacyclic triterpenoids with abundant amounts of ursolic acid, maslinic acid and uvaol. The most prominent cutin compounds were C16 and C18‒type monomers dominated by 9(10),16-diOH-hexadecanoic acid and 9,10-epoxy-ω-OH-octadecanoic acid, respectively. Relatively high water permeability with a value of 5.1 × 10-4 m s-1 was detected for guava fruit. The lower efficiency of the cuticle as barrier to transpiration in guava fruit, as compared to that of other reported fruits, leaves, and petals, was seemingly related to the relatively short average chain-length of acyclic compounds in wax mixtures. These findings provide useful insights linking the chemical composition of the cuticular membrane that covers plant organs to putative physiological roles.