Effects of fermented green-loofah and green-papaya on nitric oxide secretion from murine macrophage raw 264.7 cells.

To clarify the effect of lactic acid bacteria (LAB) fermentation on the immunomodulation capacity of green-loofah and green-papaya, aqueous suspensions prepared from the fresh and dry-powdered vegetables were fermented by Lactococcus lactis subsp. lactis Uruma-SU1 and Lactobacillus plantarum Uruma-SU4. Fermented and non-fermented suspensions were added to murine macrophage RAW264.7 culture with and without Escherichia coli O111 lipopolysaccharide (LPS). In the absence of LPS, nitric oxide (NO) secretion was elevated significantly in LAB fermented suspensions compared to that in non-fermented suspensions. NO production in fermented suspensions was observed even at low sample concentrations, but it was attenuated in the centrifuged supernatant. With LPS treatment, inhibition of NO secretion was shown with the high concentration of the non-fermented and also fermented samples. These results suggest that fermented green-loofah and green-papaya suspensions can play both immunostimulatory and anti-inflammatory roles at low and high doses, respectively.

Genome-wide transcriptome profiling reveals novel insights into Luffa cylindrica browning.

Luffa cylindrica (sponge gourd) is one of the most popular vegetables in China. Production and consumption of L. cylindrica are limited due to postharvest browning; however, little is known about the genetic regulation of the browning process. In the present study, transcriptome profiles of L. cylindrica cultivars, YLB05 (browning resistant) and XTR05 (browning sensitive), were analyzed using next-generation sequencing to clarify the genes and mechanisms associated with browning. A total of 9.1 Gb of valid data including 116,703 unigenes (>200 bp) were obtained and 39,473 sequences were annotated by alignment against five public databases. Of these, there were 27,407 genes assigned to 747 Gene Ontology functional categories; and 12,350 genes were annotated with 25 Eukaryotic Orthologous Groups (KOG) categories with 343 KOG functional terms. Additionally, by searching against the Kyoto Encyclopedia of Genes and Genomes database, 8689 unigenes were mapped to 189 pathways. Furthermore, there were 24,556 sequences found to be differentially regulated, including 4344 annotated unigenes. Several genes potentially associated with phenolic oxidation, carbohydrate and hormone metabolism were found differentially regulated between the cultivars of different browning sensitivities. Our results suggest that elements involved in enzymatic processes and other pathways might be responsible for L. cylindrica browning. The present study provides a comprehensive transcriptome sequence resource, which will facilitate further studies on gene discovery and exploiting the fruit browning mechanism of L. cylindrica.

The sub/supra-optimal temperature-induced inhibition of photosynthesis and oxidative damage in cucumber leaves are alleviated by grafting onto figleaf gourd/luffa rootstocks.

Shoot-root communication is involved in plant stress responses, but its mechanism is largely unknown. To determine the role of roots in stress tolerance, cucumber (Cucumis sativus) shoots from plants with roots of their own or with figleaf gourd (Cucurbita ficifolia, a chilling-tolerant species) or luffa (Luffa cylindrica (L.) M. Roem., a heat-tolerant species) rootstocks were exposed to low (18/13°C), optimal (27/22°C) and high (36/31°C) temperatures, respectively. Grafting onto figleaf gourd and luffa rootstocks significantly alleviated chilling and heat-induced reductions, respectively, in biomass production and CO(2) assimilation capacity in the shoots, while levels of lipid peroxidation and protein oxidation were decreased. Figleaf gourd and luffa rootstocks upregulated a subset of stress-responsive genes involved in signal transduction (MAPK1 and RBOH), transcriptional regulation (MYB and MYC), protein protection (HSP45.9 and HSP70), the antioxidant response (Cu/Zn-SOD, cAPX and GR), and photosynthesis (RBCL, RBCS, RCA and FBPase) at low and high growth temperatures, respectively, and this was accompanied by increased activity of the encoded enzymes and reduced glutathione redox homeostasis in the leaves. Moreover, Heat Shock Protein 70 (HSP70) expression in cucumber leaves was strongly induced by the luffa rootstock at the high growth temperature but slightly induced by the figleaf gourd rootstock at low or high growth temperatures. These results indicate that rootstocks could induce significant changes in the transcripts of stress-responsive and defense-related genes, and the ROS scavenging activity via unknown signals, especially at stressful growth temperatures, and this is one of mechanisms involved in the grafting-induced stress tolerance.

Long-read sequencing and de novo assembly of the Luffa cylindrica (L.) Roem. genome.

Sponge gourd (Luffa cylindrica (L.) Roem.) or luffa is a diploid herbaceous plant with 26 chromosomes (2n = 26) and belongs to the family Cucurbitaceae. To address the limited knowledge of the genome of Luffa species, the chromosome-level genome of L. cylindrica was assembled and analysed using PacBio long reads and Hi-C data. We combined Hi-C data with a draft genome assembly to generate chromosome-length scaffolds. Thirteen scaffolds corresponding to the 13 chromosomes were assembled from 1,156 contigs to a final size of 669 Mb with a contig N50 size of 5 Mb and a scaffold N50 size of 53 Mb. After removing redundant sequences, 416.31 Mb (62.18% of the genome) of repeat sequences was detected. Subsequently, 31,661 protein-coding genes with an average of 5.69 exons per gene were identified in the L. cylindrica genome using de novo methods, transcriptome data and homologue-based approaches. In addition, 27,552 protein-coding genes (87.02%) were annotated in five databases. According to the phylogenetic analysis, L. cylindrica is closely related to Cucurbita and Cucumis species and diverged from their common ancestor ~28.6-67.1 million years ago. Genome collinearity analysis was performed in Cucurbita moschata, Cucumis sativus and L. cylindrica, and it demonstrated a high degree of conserved gene order in these three species. The completeness of the genome will provide high-quality genomic knowledge on breeding and reveal genetic variation in L. cylindrica.

Identification of browning-related microRNAs and their targets reveals complex miRNA-mediated browning regulatory networks in Luffa cylindrica.

As a non-coding and endogenous small RNA, MicroRNA (miRNA) takes a vital regulatory role in plant growth and development. Long-term storage and processing of many fruits and vegetables, including Luffa, are subject to influences from browning, a common post-harvest problem that adversely affects flavor, aroma, and nutritional value. The browning regulatory networks mediated by miRNA, however, remain largely unexplored. For a systematic identification of browning-responsive miRNAs and the targets, we built two RNA libraries from Luffa pulps of near-isogenic line, with resistant and sensitive browning characteristics respectively, and then sequenced them using Solexa high-throughput technology. We consequently identified 179 known miRNAs that represent 17 non-conserved miRNA families and 24 conserved families, as well as 84 potential novel miRNAs, among which 16 miRNAs (eight known and eight novel miRNAs) were found to exhibit significant differential expressions and were thus identified as browning-related miRNAs. We then studied those browning-responsive miRNAs and the corresponding targets with RT-qPCR and finally validated their expression patterns. The results revealed that the expression patterns are specific to plant development stages and the miRNAs are identified with 39 target transcripts, which involve in plant development, defense response, transcriptional regulation, and signal transduction. After characterizing these miRNAs and their targets, we propose a browning regulatory network model of miRNA-mediatation in this paper. The findings of the work are helpful for the understanding of miRNA-mediated regulatory mechanisms of browning in Luffa, and will facilitate genetic improvement of pulp characteristics in Luffa.

Genetic analysis of fruit shape traits at different maturation stages in sponge gourd.

The fruit shape is important quantitative trait closely related to the fruit quality. However, the genetic model of fruit shapes has not been proposed. Therefore, in the present study, analysis of genetic effects for fruit shape traits (fruit length and fruit perimeter) in sponge gourd was conducted by employing a developmental genetic model including fruit direct effects and maternal effects. Analysis approaches of unconditional and conditional variances were applied to evaluate the genetic behavior of fruit shape traits at economical and physiological maturation times. The results of variance analysis indicated that fruit length and fruit perimeter were simultaneously affected by fruit direct genetic effects and maternal effects. Fruit direct genetic effects were relatively more important for fruit shape traits at whole developmental period. The gene expression was most active at the economical maturation stage (1 approximately 12 d after flowering) for two shape traits, and the activation of gene was mostly due to direct dominance effects at physiological maturation stage (13 approximately 60 d after flowering). The coefficients due to different genetic effects, as well as the phenotypic correlation coefficients, varied significantly between fruit shape traits themselves at various maturation stages. The results showed that it was relatively easy to improve fruit shape traits for industrial purpose by carefully selecting the parents at economical maturation stage instead of that at physiological maturation stage.

De novo sequencing and analysis of the transcriptome during the browning of fresh-cut Luffa cylindrica 'Fusi-3' fruits.

Fresh-cut luffa (Luffa cylindrica) fruits commonly undergo browning. However, little is known about the molecular mechanisms regulating this process. We used the RNA-seq technique to analyze the transcriptomic changes occurring during the browning of fresh-cut fruits from luffa cultivar 'Fusi-3'. Over 90 million high-quality reads were assembled into 58,073 Unigenes, and 60.86% of these were annotated based on sequences in four public databases. We detected 35,282 Unigenes with significant hits to sequences in the NCBInr database, and 24,427 Unigenes encoded proteins with sequences that were similar to those of known proteins in the Swiss-Prot database. Additionally, 20,546 and 13,021 Unigenes were similar to existing sequences in the Eukaryotic Orthologous Groups of proteins and Kyoto Encyclopedia of Genes and Genomes databases, respectively. Furthermore, 27,301 Unigenes were differentially expressed during the browning of fresh-cut luffa fruits (i.e., after 1-6 h). Moreover, 11 genes from five gene families (i.e., PPO, PAL, POD, CAT, and SOD) identified as potentially associated with enzymatic browning as well as four WRKY transcription factors were observed to be differentially regulated in fresh-cut luffa fruits. With the assistance of rapid amplification of cDNA ends technology, we obtained the full-length sequences of the 15 Unigenes. We also confirmed these Unigenes were expressed by quantitative real-time polymerase chain reaction analysis. This study provides a comprehensive transcriptome sequence resource, and may facilitate further studies aimed at identifying genes affecting luffa fruit browning for the exploitation of the underlying mechanism.

A multiscale study on the structural and mechanical properties of the luffa sponge from Luffa cylindrica plant.

Cellular materials that are often observed in biological systems exhibit excellent mechanical properties at remarkably low densities. Luffa sponge is one of such materials with a complex interconnecting porous structure. In this paper, we studied the relationship between its structural and mechanical properties at different levels of its hierarchical organization from a single fiber to a segment of whole sponge. The tensile mechanical behaviors of three single fibers were examined by an Instron testing machine and the ultrastructure of a fractured single fiber was observed in a scanning electronic microscope. Moreover, the compressive mechanical behaviors of the foam-like blocks from different locations of the sponge were examined. The difference of the compressive stress-strain responses of four sets of segmental samples were also compared. The result shows that the single fiber is a porous composite material mainly consisting of cellulose fibrils and lignin/hemicellulose matrix, and its Young's modulus and strength are comparable to wood. The mechanical behavior of the block samples from the hoop wall is superior to that from the core part. Furthermore, it shows that the influence of the inner surface on the mechanical property of the segmental sample is stronger than that of the core part; in particular, the former's Young's modulus, strength and strain energy absorbed are about 1.6 times higher. The present work can improve our understanding of the structure-function relationship of the natural material, which may inspire fabrication of new biomimetic foams with desirable mechanical efficiency for further applications in anti-crushing devices and super-light sandwich panels.

Loofa (Luffa cylindrica) sponge: review of development of the biomatrix as a tool for biotechnological applications.

The review discusses the development of loofa sponge (Luffa cylindrica) as a biotechnological tool and the diversity of applications in which it has been successfully used since it was first reported as a matrix for the immobilization of microbiological cells in 1993. The fibro-vascular reticulated structure, made up of an open network of random lattices of small cross-sections coupled with very high porosity (79-93%), having very low density (0.02-0.04 g/cm(3) ), and high specific pore volume (21-29 cm(3) /g), has the characteristics of a carrier/scaffold well-suited for cell immobilization. This has been confirmed through the immobilization of cells of diverse types, including filamentous and microalgae, fungi, bacteria, yeasts, higher plants, and human and rat hepatocytes. The cells immobilized in loofa sponge have performed well and better than free suspended cells and those immobilized in conventionally used natural and synthetic polymeric materials for the production of ethanol, organic acids, enzymes, and secondary metabolites. The loofa-immobilized cell systems have been efficiently used for the treatment of wastewaters containing toxic metals, dyes, and chlorinated compounds, and the technology has been used to develop biofilms for the remediation of domestic and industrial wastewaters rich in inorganic and organic matter. In addition, three-dimensional loofa sponge scaffolds for hepatocyte culture have been suggested to have the potential for development into a bioartificial liver device. Loofa sponge is a cost-effective, eco-friendly, and easy to handle matrix that has been used successfully as a biotechnological tool in a variety of systems, purposes, and applications.