Seed Longevity and Biotic Defense

During development, seeds acquire a range of physiological traits that are crucial for successful seedling establishment in the field, such as vigorous and homogenous germination. These traits rely on the remarkable capacity of seeds to remain alive for extended periods of time when stored in the dry state (longevity). The search for the mechanisms regulating seed longevity is a longstanding goal in agriculture because of its impact on crop yields, especially in stressful conditions, weed emergence and its importance as a means to preserve plant genetic resources.

To identify key genes regulating the acquisition of longevity during seed maturation of the legume model Medicago truncatula, we generated a robust, stable co-expression network (MatNet) from seed developmental time courses obtained in five growth environments. A co-expression module related to the acquisition of longevity was inferred from MatNet. Comparative analysis with Arabidopsis and mining Arabidopsis interaction databases demonstrated high conserved connectivity between both species. Functional analysis of transcription factors that are present in the longevity module revealed the importance of regulatory pathways that govern defense against biotic stress in the acquisition of longevity during seed development. This represents an original example of co-adaptation where seed longevity has evolved by co-opting existing genetic pathways regulating the activation of defense against necrotrophic pathogens to ensure prolonged survival in the dry state. Understanding the regulation of seed vigor should therefore take into the impact of both abiotic and biotic stresses.

This work was carried out by the Conserto team of the IRHS, in collaboration with the Luxembourg Centre for Systems Biomedicine (Luxembourg), the Centre for the Analysis of Genome Evolution and Function at the University of Toronto (Canada) and the Shanghai Center for Plant Stress Biology, (China). Matnet is available for datamining at www.matnet.ml

Publications:

• Righetti, K., Vu, J. L., Pelletier, S., Vu, B. L., Glaab, E., Lalanne, D., Pasha, A., Patel, R. V., Provart, N. J., Verdier, J., Leprince, O., & Buitink, J. (2015). Inference of Longevity-Related Genes from a Robust Coexpression Network of Seed Maturation Identifies Regulators Linking Seed Storability to Biotic Defense-Related Pathways. The Plant Cell. vol. 27 no. 10: 2692-2708 DOI: http://dx.doi.org/10.1105/tpc.15.00632
• Mach J (2015) A Sleep Like Death: Identification of Genes Related to Seed Longevity in Medicago truncatula and Arabidopsis. Plant Cell 2015;27;2671; originally published online October 6, 2015; DOI 10.1105/tpc.15.00833.