Wednesday, November 15, 2006

Salt Tolerance in the Genetic Base of U.S. and Canadian Soybean.

Margarita R. Villagarcia1, A. J. Cardinal2, Thomas Carter Jr.1, James G. Shannon3, and H. R. Boerma4. (1) USDA-ARS, 3127 Ligon St., Raleigh, NC 27607, (2) North Carolina State University, 840 Method Rd Unit 3, Raleigh, NC 27695, (3) University of Missouri, Delta Center, P O Box 160 147 Stae Highway T, Portageville, MO 63873, (4) Ctr for Applied Genetic Tech., Athens, GA 30602-7272

 Salt toxicity is a common problem for soybean grown on rice lands in Arkansas or on low-lying flood-prone fields near the bays and sounds of  the Atlantic Coast.  Most cultivars are susceptible. However, the soybean ancestor S-100, its landmark progeny Lee, and many of Lee’s progeny (e.g. Forrest) are salt tolerant.  Most other soybean ancestors and their progeny have an unknown salt reaction, especially those adapted to the Midwest.  37 ancestors (or their representative descendents) and 10 landmark cultivars were compared for salt reaction in a series of replicated greenhouse experiments in NC and MO. NaCl was added to solution and applied daily to test genotypes.  In NC, plants were grown in sand culture, using 30-cm diameter pots and 115 milli-molar NaCl. In MO, micro pots (i.e. trays with inserts) were employed.  Leaf chlorosis was rated after a few weeks of treatment.  Agreement between MO and NC results was good. 8 ancestors, in addition to S-100, were not significantly different from the tolerant checks Lee and Forrest:  AK (Harrow), Illini, Adams, Fiskeby III,  Fiskeby_840_7_3, Capital, Flambeau, Bilomi #3.  The PI 88788, Peking and Dunfield appeared to have intermediate response (i.e. less damage than susceptible check Essex).  All 10 landmark cultivars were susceptible, including Harosoy, Williams, and Clark. Discovery of salt tolerance in very early maturity ancestors (e.g. Fiskeby III) was a surprising result.  SSR marker analysis of the ancestors is in progress.  Allelism tests are being initiated. The salt reaction of ancestors was used to predict salt reaction of modern cultivars using pedigree analysis.