SCAN:Population genomics of Medicago truncatula to identify mechanisms of salinity adaptation

SCAN Seminar- ITQB

Title: Population genomics of Medicago truncatula to identify mechanisms of salinity adaptation

Speaker: Matilde Cordeiro

From: Plant Cell Biotechnology Laboratory

Abstract:

Population genomics of Medicago truncatula to identify mechanisms of salinity adaptation

Matilde Cordeiroa,b, Pedro Fevereiroa, Douglas Cookb, aInstituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, EAN, 2781-901 Oeiras, Portugal. bDepartment of Plant Pathology, University of California in Davis, One Shields Ave, Robbins Hall, 95616 CA, USA.E-mail: mcordeiro@ucdavis.edu

Medicago truncatula (Mtr) is a common legume in the Mediterranean Basin and is a model system in molecular, ecological, evolutionary, and physiological biology.  My research integrates molecular and ecological methods to identify the genetic basis and mechanisms of salinity tolerance in natural populations from Tunisia and Portugal that occur in saline and non-saline environments. Soil salinity is a major abiotic factor that limits plant yield and affects species distribution. Identifying the genes and the traits that are favoured in each environment will help understand how different populations evolved in saline and non-saline environments. My presentation focuses on 1) the identification of candidate genes and potential traits associated with salinity tolerance, and 2) the comparison of the mechanisms for salinity adaptation between Tunisia and Portuguese populations.

To identify genes associated with salinity tolerance, I used whole genome scans (Affymetrix GeneChip hybridization and Solexa sequencing) from genotypes from saline and non-saline environments.  I found alleles from nine genes that assort with soil type that may be involved in cuticle formation and might play a role in salinity tolerance. Greenhouse studies where genotypes from two saline and two non-saline populations from Tunisia were grown in 0mM and 100mM NaCl showed evidence that the populations are locally adapted to soil salinity. To compare mechanisms of salinity adaptation between the Tunisian and Portuguese populations, I conducted a field reciprocal transplant experiment in early 2011 including genotypes from four Tunisian populations (two saline and two non-saline) and four Portuguese populations (two saline and two non-saline). These data will be used to test whether Tunisian Mtr are adapted to salinity independently of the environment, if Portuguese populations of Mtr are locally adapted, and if there is a common mechanism for salinity adaptation in Mtr.  Using an integrated approach, I expect to identify what traits are favoured under salinity, how the traits relate to fitness and what genes influence these traits in Mtr.

Keywords: Medicago truncatula, salinity, genes, adaptation, population