Project description:In Arabidopsis, treating shoots with uniconazole can result in enhanced primary root elongation and bolting delay. Uniconazole spraying has become an important cultivation technique in controlling the flowering and improving the fruit-setting of litchi. However, the mechanism by which uniconazole regulates the complicated developmental processes in litchi remains unclear. This study aimed to determine which signal pathways and genes drive the responses of litchi inflorescences to uniconazole treatment. We monitored the transcriptional activity in inflorescences after uniconazole treatment by Illumina sequencing technology. The global expression profiles of uniconazole-treated litchi inflorescences were compared with those of the control, and 4051 differentially expressed genes were isolated. KEGG pathway enrichment analysis indicated that the plant hormone signal transduction pathway served key functions in the flower developmental stage under uniconazole treatment. Basing on the transcriptional analysis of genes involved in flower development, we hypothesized that uniconazole treatment increases the ratio of female flowers by activating the transcription of pistil-related genes. This phenomenon increases opportunities for pollination and fertilization, thereby enhancing the fruit-bearing rate. In addition, uniconazole treatment regulates the expression of unigenes involved in numerous transcription factor families, especially the bHLH and WRKY families. These findings suggest that the uniconazole-induced morphological changes in litchi inflorescences are related to the control of hormone signaling, the regulation of flowering genes, and the expression levels of various transcription factors. This study provides comprehensive inflorescence transcriptome data to elucidate the molecular mechanisms underlying the response of litchi flowers to uniconazole treatment and enumerates possible candidate genes that can be used to guide future research in controlling litchi flowering.
Project description:BACKGROUND: Recent studies have demonstrated that cellular energy is a key factor switching on ripening and senescence of fruit. However, the factors that influence fruit energy status remain largely unknown. RESULTS: HPLC profiling showed that ATP abundance increased significantly in developing preharvest litchi fruit and was strongly correlated with fruit fresh weight. In contrast, ATP levels declined significantly during postharvest fruit senescence and were correlated with the decrease in the proportion of edible fruit. The five gene transcripts isolated from the litchi fruit pericarp were highly expressed in vegetative tissues and peaked at 70 days after flowering (DAF) consistent with fruit ADP concentrations, except for uncoupling mitochondrial protein 1 (UCP1), which was predominantly expressed in the root, and ATP synthase beta subunit (AtpB), which was up-regulated significantly before harvest and peaked 2 days after storage. These results indicated that the color-breaker stage at 70 DAF and 2 days after storage may be key turning points in fruit energy metabolism. Transcript abundance of alternative oxidase 1 (AOX1) increased after 2 days of storage to significantly higher levels than those of LcAtpB, and was down-regulated significantly by exogenous ATP. ATP supplementation had no significant effect on transcript abundance of ADP/ATP carrier 1 (AAC1) and slowed the changes in sucrose non-fermenting-1-related kinase 2 (SnRK2) expression, but maintained ATP and energy charge levels, which were correlated with delayed senescence. CONCLUSIONS: Our results suggest that senescence of litchi fruit is closely related with energy. A surge of LcAtpB expression marked the beginning of fruit senescence. The findings may provide a new strategy to extend fruit shelf life by regulating its energy level.
Project description:Background:Lectins are highly important biomolecules to study several biological processes. A novel ?-D-glucose/mannose specific lectin was isolated from the seeds of litchi fruits (Litchi chinensis) and its various biophysical and biochemical properties were studied. Methods:Purification was done by successive Sephadex G 100 and Con A-Sepharose 4B affinity chromatography. SDS-PAGE, Surface Plasmon Resonance (SPR), steady state absorbance, fluorescence, time-correlated single-photon counting, circular dichroism and antibiofilm activity by measuring total protein estimation and azocasein degradation assay have been performed. Results:The purified lectin is a homodimer of molecular mass ~ 54 kDa. The amount of lectin required for hemagglutination of normal human O erythrocytes was 6.72 µg/ml. Among the saccharides tested, Man-?-(1,6)-Man was found to be the most potent inhibitor (0.01 mM) determined by hemagglutination inhibition assay. Steady state and time resolved fluorescence measurements revealed that litchi lectin formed ground state complex with maltose (Ka=4.9 (±0.2)×104 M-1), which indicated static quenching (Stern-Volmer (SV) constant Ksv=4.6 (±0.2)×104 M-1). CD measurements demonstrated that litchi lectin showed no overall conformational change during the binding process with maltose. The lectin showed antibiofilm activity against Pseudomonus aeruginosa. Conclusions:A novel homodimeric lectin has been purified from the seeds of litchi fruits (Litchi chinensis) having specificity for ?-d-glucose/mannose. The thermodynamics and conformational aspects of its interaction with maltose have been studied in detail. The antibiofilm activity of this lectin towards Pseudomonus aeruginosa has been explored. General significance:The newly identified litchi lectin is highly specific for ?-d-glucose/mannose with an important antibiofilm activity towards Pseudomonus aeruginosa.
Project description:BackgroundThe GRAS gene family plays crucial roles in multiple biological processes of plant growth, including seed development, which is related to seedless traits of litchi (Litchi chinensis Sonn.). However, it hasn't been fully identified and analyzed in litchi, an economic fruit tree cultivated in subtropical regions.ResultsIn this study, 48 LcGRAS proteins were identified and termed according to their chromosomal location. LcGRAS proteins can be categorized into 14 subfamilies through phylogenetic analysis. Gene structure and conserved domain analysis revealed that different subfamilies harbored various motif patterns, suggesting their functional diversity. Synteny analysis revealed that the expansion of the GRAS family in litchi may be driven by their tandem and segmental duplication. After comprehensively analysing degradome data, we found that four LcGRAS genes belong to HAM subfamily were regulated via miR171-mediated degradation. The various expression patterns of LcGRAS genes in different tissues uncovered they were involved in different biological processes. Moreover, the different temporal expression profiles of LcGRAS genes between abortive and bold seed indicated some of them were involved in maintaining the normal development of the seed.ConclusionOur study provides comprehensive analyses on GRAS family members in litchi, insight into a better understanding of the roles of GRAS in litchi development, and lays the foundation for further investigations on litchi seed development.