Jeudis d'Agap : Deconstructing Evolutionary Outcomes for Crop Improvement: Durable Disease Resistance and Environmental Adaptation in Maize_Jeudi 18 octobre 2018

18 octobre 2018

de 11h00 à 12h00, Salle 159 bâtiment 3 (extension) - Cirad, av. Agropolis, Lavalette, France

Présenté par Randall J. Wisser (Université Deleware, USA), généticien quantitatif du maïs

Résumé

Studying evolutionary outcomes, such as disease resistance and local adaptation, can generate actionable knowledge for crop improvement. This seminar will cover two tracks of research on maize aimed at identifying, characterizing and mining genomic variation for plant breeding.

Quantitative disease resistance (QDR) in plants is a natural form of durable resistance (i.e. resistance remains effective across space and time in crop production systems). This has driven an interest in understanding the nature of QDR for more than 50 years, and yet the complex biology of QDR is only beginning to be elucidated. Through systematic dissection of the genetic architecture underlying QDR to fungal pathogens of maize, we have produced a body of research that indicates a multi-functional basis for resistance expressed under field conditions as measured on whole plants. However, these findings lack a connection to the 3D microscopic features that underlie variation in pathogenesis. By integrating quantitative genetics, a novel tissue-scale cell-level bioimaging approach and computer vision, we have developed a platform for uncovering mechanisms of defense and parameterizing plant-pathogen interactions in a quantitative framework. This development opens new doors for studying QDR while contributing to the advancement of cellular phenomics in plants.

For many traits, including QDR, beneficial alleles can be mined from the vast natural variation present in maize, but these alleles tend to exist in populations that are phenologically maladapted to a desired target production environment. This presents a fundamental barrier to the diversification and improvement of maize outside its native range. In order to harness untapped gene diversity for temperate maize production, a set of connected experiments have been performed to phenotypically, genetically, and ecologically characterize genomic loci underlying the seasonal adaptation of tropical maize to temperate environments. Analysis of experimentally evolved populations using novel designs is uncovering multiple facets of the genomic basis for adaptation: (i) a shifting, quasi-polygenic architecture; (ii) genomic context dependency; and (iii) local haplotype series are found to associate with the response to selection for adaptation. These and other results are enabling new approaches to be envisioned for more rapid integration of genetic diversity to facilitate development of a more climate resilient crop system.

Contact

Bertrand Muller
Inra, Montpellier
France