The 2011 ASHS Annual Conference

Aluminum (Al) toxicity in acid soils is one of the major abiotic stresses in agriculture, affecting approximately 40 % of the world’s arable land. To study Al tolerance in pasture legumes, we have screened 165 Medicago truncatula ecotypes and mutant lines for their response to Al toxicity. Seedlings were grown in an agarose medium that contained three levels of Al, and root growth was measured at 72 h as a parameter of Al sensitivity. Populations (F₁) were generated by hand pollination between three tolerant lines and four sensitive lines. Hybrid seeds were obtained from five crosses; however, only three crosses produced healthy F₁ seedlings. Populations (F₂) generated from these crosses were then phenotyped, using Al-containing agarose medium. Seedlings from a cross between an Al-sensitive mutant line and an Al-tolerant ecotype showed little differences in root growth under 0 Al, but a segregating pattern of root growth under Al toxic conditions. Leaf tissues from the extreme phenotypes were collected for DNA extraction and will be used later in a bulk segregation analysis.