Search

【Objective】Endophytic bacteria exert an important role in plant growth and development. The study aims to analyze the community structure and diversity of endophytic bacteria in pulp of different litchi varieties, and screen and utilize the potential endophytic bacteria resources, which would provide references for further research on the interaction between litchi and endophytic bacteria.【Method】The pulp tissues of 6 different litchi varieties were used as materials. MiSeq high-throughput sequencing technology was used to compare and analyze the community composition and dominant flora of endophytic bacteria at phylum, family, genus and species classification levels in pulp tissues after the V3~V4 region of 16S rDNA was amplified by PCR. The diversity of endophytic bacteria was evaluated combined with Alpha diversity analysis.【Result】A total of 2 139 086 sequences of endophytic bacteria 16S rDNA were obtained in the V3~V4 region of 6 litchi varieties, and the average length of amplified sequences was 376 bp. There was no significant difference in the abundance and diversity of endophytic bacteria in different litchi varieties. At the phylum classification level, Proteobacteria was the main dominant bacterial group in litchi pulp tissue, followed by Actinomyces. At the levels of family, genus and species classification, the endophytic bacterial community structure of different litchi varieties was similar, but the bacterial abundance proportion was different. Differential bacterial community analysis showed that the Pseudomonas, Pectobacterium, Ochrobactrum and Dickeya were significantly enriched in the high-quality varieties of 'Edanli', 'Nuomici' and 'Guanyinlv'. In addition, Bradyrhizobium and Snodgrassella were only enriched in the 'Edanli'. The clustering analysis of relative abundance of bacteria showed that 'Guanyinlv', 'Nuomici' and 'Edanli', had higher similarity. Alpha diversity analysis showed that there were differences in the abundance and diversity of endophytic flora in pulps of 6 litchi varieties, but the differences were not significant.【Conclusion】In this study, the community structure of endophytic bacteria in the pulp of six different litchi varieties was analyzed, and some unique microbial genera were enriched in the high-quality litchi varieties. The results could provide a theoretical basis and important references for the development and utilization of endophytic bacteria to improve litchi quality.

[Objective] Endophytic bacteria exert an important role in plant growth and development. The study aims to analyze the community structure and diversity of endophytic bacteria in pulp of different litchi varieties, and screen and utilize the potential endophytic bacteria resources, which would provide references for further research on the interaction between litchi and endophytic bacteria. [Method] The pulp tissues of 6 different litchi varieties were used as materials. MiSeq high-throughput sequencing technology was used to compare and analyze the community composition and dominant flora of endophytic bacteria at phylum, family, genus and species classification levels in pulp tissues after the V3~V4 region of 16S rDNA was amplified by PCR. The diversity of endophytic bacteria was evaluated combined with Alpha diversity analysis. [Result] A total of 2 139 086 sequences of endophytic bacteria 16S rDNA were obtained in the V3~V4 region of 6 litchi varieties, and the average length of amplified sequences was 376 bp. There was no significant difference in the abundance and diversity of endophytic bacteria in different litchi varieties. At the phylum classification level, Proteobacteria was the main dominant bacterial group in litchi pulp tissue, followed by Actinomyces. At the levels of family, genus and species classification, the endophytic bacterial community structure of different litchi varieties was similar, but the bacterial abundance proportion was different. Differential bacterial community analysis showed that the Pseudomonas, Pectobacterium, Ochrobactrum and Dickeya were significantly enriched in the high-quality varieties of ‘Edanli’, ‘Nuomici’ and ‘Guanyinlv’. In addition, Bradyrhizobium and Snodgrassella were only enriched in the ‘Edanli’. The clustering analysis of relative abundance of bacteria showed that ‘Guanyinlv’, ‘Nuomici’ and ‘Edanli’, had higher similarity. Alpha diversity analysis showed that there were differences in the abundance and diversity of endophytic flora in pulps of 6 litchi varieties, but the differences were not significant. [Conclusion] In this study, the community structure of endophytic bacteria in the pulp of six different litchi varieties was analyzed, and some unique microbial genera were enriched in the high-quality litchi varieties. The results could provide a theoretical basis and important references for the development and utilization of endophytic bacteria to improve litchi quality. [ABSTRACT FROM AUTHOR]

The deterioration of the quality of litchi pulp is closely related to oxygen and heat treatment. This study compared the effects of conventional beating (CB) and low-oxygen beating (LB) on the quality of litchi pulp, and the effect of low-oxygen beating combined with high hydrostatic pressure (HHP) and heat treatment on the quality of litchi pulp during storage at 4 ℃ was also studied. The results showed that when compared to conventional beating, low-oxygen beating had no significant effect on the total soluble solid, pH and total acid of litchi pulp (P>0.05), while the L* value increased significantly (P

Studies on how temperature affects the postharvest quality of litchi have focused mainly on pericarp browning but rarely on the metabolites in postharvest litchi pulp. In this study, the differences in respiration rates, total soluble solid content, and titratable acid content demonstrated that room and low temperatures have different effects on the quality of "Feizixiao" litchi pulp. UHPLC‐ESI‐QTOF‐MS/MS analysis was performed to compare the differentially expressed metabolites (DEMs) in litchi pulp after 8 days of storage at room temperature (RT‐8 d) with those in litchi pulp after 28 days of storage at low temperature (LT‐28 d). Nineteen carbohydrates (phosphohexoses, sorbitol, and mannose), fifteen acids, seven amino acids, nine energy metabolites and nucleotides, and six aliphatic and secondary metabolites were identified as common DEMs in RT‐8 d and LT‐28 d pulps. These findings indicated active fructose and mannose metabolism and increased catabolism of nicotinate, nicotinamide, alanine, aspartate, and glutamate. Four carbohydrates (mainly phosphohexoses), five acids, ten amino acids, three aliphatic and secondary metabolites, and one hormone were identified as unique DEMs in RT‐8 d pulp, the consumption of key metabolites in glycolysis and the tricarboxylic acid cycle, and accumulation of phenylalanine, tyrosine, and tryptophan. Active consumption of nucleotide metabolites and biosynthesis of aliphatics in LT‐28 d pulp were indicated by unique DEMs (eleven carbohydrates, four acids, seven amino acids, seven energy metabolites and nucleotides, and six aliphatic and secondary metabolites). These results provided an unambiguous metabolic fingerprint, thereby revealing how room and low temperatures differentially influenced the quality of litchi pulp. [ABSTRACT FROM AUTHOR]

Litchi polysaccharide (LP) was extracted from litchi pulp. Its chemical composition, microstructure, zeta potential, flow and viscoelastic behavior were investigated. LP contained uronic acid (41.18%), neutral sugar (42.23%), and protein (2.72%). The monosaccharide composition was mostly arabinose, galactose, and a small amount of mannose, rhamnose and glucose. Scanning electron microscopy (SEM) showed LP was porous network structure. LP concentration had no effect on its zeta potential value while salts reduced them. LP showed shear-thinning behavior during the tested shear rate range. The power-law model was used to evaluate the flow behavior of LP; both its flow behavior index and consistency index changed with different concentrations. The viscosity of LP increased under acidic conditions (pH 2–4), but was stable with heat treatment. The LP dispersion displayed as a liquid viscoelastic behavior in 1% and 2% concentrations and behaved as an elastic gel at 3% concentration as well as the addition of NaCl and CaCl 2 . [ABSTRACT FROM AUTHOR]

Dried litchi pulp has been used in traditional remedies in China for many years to treat various diseases, and the therapeutic activity has been, at least partly, attributed to the presence of bioactive polysaccharides. Polysaccharide-protein complexes from vacuum freeze-(VF), vacuum microwave-(VM) and heat pump (HP) dried litchi pulp, which were coded as LP-VF, LP-VM and LP-HP, were comparatively studied on the physicochemical and immunomodulatory properties. LP-HP had a predominance of galactose, while glucose was the major sugar component in LP-VF and LP-VM. Compared with LP-VF and LP-VM, LP-HP contained more aspartate and glutamic in binding protein. LP-HP also exhibited a stronger stimulatory effect on splenocyte proliferation at 200 μg/mL and triggered higher NO, TNF-α and IL-6 secretion from RAW264.7 macrophages. Different drying methods caused the difference in physicochemical properties of polysaccharide-protein complexes from dried litchi pulp, which resulted in significantly different immunomodulatory activity. HP drying appears to be the best method for preparing litchi pulp to improve its immunomodulatory properties.

Three water-soluble hetero-polysaccharides, designated LP1–3, were isolated from litchi pulp. Their structures, solution properties and immunomodulatory activities were evaluated. LP1 contained (1 → 4,6)-β- d -Glc and (1 → 4)-α- l -Gal, while LP2 contained (1 → 3)-α- l -Ara and (l → 2)-β- d -Gal, and LP3 contained α- l -Ara and (l → 4)-β-Rha. Their molecular weights ranged from 105,880 to 986,470 g/mol. LP1 had a spherical conformation with hyper-branched structure and LP2 was semi-flexible chain, while the polysaccharide chains of LP3 were cross linked to form network-like conformation in solution. In addition, all fractions strongly stimulated mesenteric lymph node cell proliferation, IFN-γ and IL-6 secretion in the dose range of 25–100 μg/mL compared with untreated control group ( p < 0.05). LP1 exhibited the strongest stimulation of mesenteric lymph node cell proliferation and cytokine secretion, which may be attributed to its unique chemical structure and chain conformation. This is the first report on the solution properties and intestinal immunity activities of polysaccharides from litchi pulp. [ABSTRACT FROM AUTHOR]

Litchi (Litchi chinensis Sonn.) fruit easily deteriorates and has a short storage life. Room temperature storage is widely used during short-distance transportation and sale of litchi fruits. This study explored the changes in the quality of litchi pulp at room temperature storage using transcriptomics, proteomics, and metabolomics analyses. The results illustrated significant changes in carbohydrate metabolism pathways. Increases in d -ribose-5-phosphate, d -ribose, d -mannose-6-phosphate, d -mannose, d -mannitol, D-sorbitol, and d -fructose-1-phosphate indicated that fructose and mannose metabolism, the pentose phosphate pathway, and amino sugar and nucleotide sugar metabolism competed with glycolysis for α- d -glucose, α- d -glucose-6-phosphate, and β- d -fructose-6-phosphate. Citrate and l -malic acid from the tricarboxylic acid cycle (TCA cycle) might be consumed via the biosynthesis of amino acids and lipids. Most of the differentially expressed genes and proteins related to glycolysis and the TCA cycle were downregulated, which verified that these two pathways were impeded. Flow direction changes in glycolysis and the TCA cycle might lead to energy deficiency. Upregulated activities of α-amylase and soluble acid invertase cleaved starch and sucrose into glucose and fructose, which replenished deficient energy metabolism substrates. During these processes, the changes in the content and composition of sugar and acid result in a decrease in flavor. Additionally, the polysaccharide degradation softened the texture and reduced the nutritional value. By systematically exploring the regulation of physiological changes in the pulp of litchi fruit stored at room temperature, we provid a basis for optimizing the preservation of litchi fruit and a reference for studying fruit carbohydrate metabolism. [Display omitted] [ABSTRACT FROM AUTHOR]