Development of MtSSPdb: an Integrative Database of Medicago truncatula Small Signaling Peptides

Legumes are key components of sustainable agricultural systems because they possess the ability to fix nitrogen by forming symbiotic relationships with rhizobia (soil bacteria) leading to formation of root nodules. Medicago truncatula has been chosen as a premier model legume because it is closely related to the economically important forage species, alfalfa. Small signaling peptides (SSPs) are emerging as an important class of regulatory molecules in plants, which is especially important to legume research since recent discoveries suggest that SSPs may play important roles in nodule morphogenesis, root development and plant adaptation to nutrient limitations.

Recently, we re-annotated the M. truncatula genome (both Mt3.5v5 and Mt4.0v1 genome assemblies) using 338 RNA-seq libraries and protein/EST sequences that are publicly available. In total, 70,210 gene models were predicted, out of which 4,261 were chosen as SSP candidates based on protein length and signal peptide predictions. Curation and experimental identification are being performed to further screen and classify these candidates.

To host and present these newly identified SSP genes and families, we are developing a web based database namely MtSSPdb: The Medicago truncatula Small Signaling Peptide Database. This will include information about SSP gene models, classification, gene expression atlas, and phenotypic information. Currently, we focus on the development of an intuitive web portal and the SSP Gene Expression Atlas that contains transcriptomic data from diverse biological conditions, such as macronutrient deficiencies, nodule development, salt stress, and different plant tissues. The SSP gene Atlas also provides a series of analytical features, such as tools for differential gene expression and gene co-expression analysis.