Using FIBexDB for In-Depth Analysis of Flax Lectin Gene Expression in Response to Fusarium oxysporum Infection

Plant proteins with lectin domains play an essential role in plant immunity modulation, but among a plurality of lectins recruited by plants, only a few members have been functionally characterized. For the analysis of flax lectin gene expression, we used FIBexDB, which includes an efficient algorithm for flax gene expression analysis combining gene clustering and coexpression network analysis. We analyzed the lectin gene expression in various flax tissues, including root tips infected with Fusarium oxysporum. Two pools of lectin genes were revealed: downregulated and upregulated during the infection. Lectins with suppressed gene expression are associated with protein biosynthesis (Calreticulin family), cell wall biosynthesis (galactose-binding lectin family) and cytoskeleton functioning (Malectin family). Among the upregulated lectin genes were those encoding lectins from the Hevein, Nictaba, and GNA families. The main participants from each group are discussed. A list of lectin genes, the expression of which can determine the resistance of flax, is proposed, for example, the genes encoding amaranthins. We demonstrate that FIBexDB is an efficient tool both for the visualization of data, and for searching for the general patterns of lectin genes that may play an essential role in normal plant development and defense.

Genome-wide Identification and Characterization of G-type lectin in Fragaria Vesca

Background: Lectins make up a large and diverse group of proteins in plants. G-type lectins are important type of lectins involved in plant development and defense process. However, studies about G-type lectins are limited to lectin receptor kinases.Results: In this study, genome-wide identification was carried out on G-type lectin gene family in Fragaria vesca. A total of 133 genes were found belonging to this family and they were classified into four groups: G-type lectin receptor kinases, G-type lectin kinases, G-type lectin receptor proteins and G-type lectin proteins, according to their domain organizations. Their chromosome localization, phylogenetic and evolutionary relationship were also analyzed. The results showed that tandem and dispersed duplication occurred frequently, which led to the expansion of G-type lectin gene family in F. vesca and may have increased the types of domain arrangement. The expression profile of G-type lectin genes at different developmental stages of F. vesca and under various biotic/abiotic stresses was inferred from the available databases. G-type lectin genes are actively expressed during F. vesca development and respond to multiple biotic/abiotic stresses. Additionally, to comprehend the functions of G-type lectins, we predicted strawberry genes that may co-express with these G-type lectin genes. Conclusions: G-type lectin gene family is a large gene family in F. vesca. Domain organization and expression analysis imply their functions under biotic/abiotic stresses.

Regulation of mucosal lectins in the oyster Crassostrea virginica in response to food availability and environmental factors

ABSTRACT Lectins are a large and diverse group of sugar-binding proteins involved in nonself recognition and cell-to-cell interactions. Suspension-feeding bivalves, such as the oyster Crassostrea virginica, are capable of using these molecules to bind cell surface carbohydrates of food particles, allowing particle capture and selection. The aim of this project was to assess whether the expression of mucosal lectins in C. virginica is constant or changes with the season, and to determine whether lectin expression is linked to environmental parameters and/or internal biological factors (gametogenesis). A total of 130 oysters were placed in submerged cages at a tidal estuary and monitored for changes in lectin gene expression over a 1-year period. In parallel, environmental parameters prevailing at the field site, including seawater physicochemical characteristics (temperature, salinity and dissolved oxygen), particulate organic matter and chlorophyll contents, were also monitored. Throughout the study, oysters were dissected and the gills were collected and used for the assessment of the expression of three different lectin genes (CvML, CvML3914 and CvML3912). Remaining tissues were processed for histology and the classification of the gonad development stage. Results showed that when food is abundant, such as during the spring bloom, lectin gene expressions are low, and inversely lectin levels increase with lower food levels. These findings suggest that oysters increase lectin expression to enhance the capture and ingestion of scarce food, while during spring, enough food is already being ingested and lectins are not needed. Furthermore, results showed that as the energy demands of oysters increase (gonad maturation), lectin gene expressions also increase to enhance selective ingestion of nutritious food particles. This study, therefore, demonstrates the seasonality of lectin gene expression in C. virginica, and suggests that lectin regulation is related to the reproduction process and abundance of high-quality food.

Immune activation by a multigene family of lectins with variable tandem repeats in oriental river prawn ( Macrobrachium nipponense )

Genomic regions with repeated sequences are unstable and prone to rapid DNA diversification. However, the role of tandem repeats within the coding region is not fully characterized. Here, we have identified a new hypervariable C-type lectin gene family with different numbers of tandem repeats (Rlecs; R means repeat) in oriental river prawn ( Macrobrachium nipponense ) . Two types of repeat units (33 or 30 bp) are identified in the second exon, and the number of repeat units vary from 1 to 9. Rlecs can be classified into 15 types through phylogenetic analysis. The amino acid sequences in the same type of Rlec are highly conservative outside the repeat regions. The main differences among the Rlec types are evident in exon 5. A variable number of tandem repeats in Rlecs may be produced by slip mispairing during gene replication. Alternative splicing contributes to the multiplicity of forms in this lectin gene family, and different types of Rlecs vary in terms of tissue distribution, expression quantity and response to bacterial challenge. These variations suggest that Rlecs have functional diversity. The results of experiments on sugar binding, microbial inhibition and clearance, regulation of antimicrobial peptide gene expression and prophenoloxidase activation indicate that the function of Rlecs with the motif of YRSKDD in innate immunity is enhanced when the number of tandem repeats increases. Our results suggest that Rlecs undergo gene expansion through gene duplication and alternative splicing, which ultimately leads to functional diversity.