MOLECULAR CHARACTERIZATION OF IRON STRESS RESPONSE IN SOYBEANS
Leorrie Atencio1, Justin Ryan Salazar1, Adrienne Moran-Lauter2, Michael Gonzales3, Steven Whitham1, Michelle Graham2.
1Iowa State University, Ames, IA, 2Corn Insects and Crop Genetics Research Unit, USDA-Agricultural Research Service, Ames, IA, 3Center for Applied Genetic Technology, The University of Georgia, Athens, GA.
Iron deficiency chlorosis (IDC) is a disease resulting from lack of useable iron that results in yield loss at the end of the season. This is particularly important in the upper Midwestern U.S. because soil conditions favor the development of IDC. Therefore, we are interested in characterizing soybeans’ short- and long-term response to iron stress. Our research takes advantage of 2 near-isogenic lines that are 98% genetically identical but differ in their iron response. Clark plants are iron efficient, while Isoclark plants are iron inefficient and develop symptoms of IDC under iron-stress conditions. Both Clark and Isoclark plants were grown in hydroponics in a greenhouse for 10 days. Plants were grown in 1 of 3 treatments: iron sufficient media for 10 days, iron deficient media for 10 days, or iron sufficient media for 8 days followed by transfer to iron deficient media for 2 days. To ensure that all plants received similar treatment, at 8 days the roots of all plants were rinsed in water and then plants were returned or transferred to the appropriate media. We used bioinformatic methods to compare RNA-seq data from the 48 generated samples. This approach allowed us to identify thousands of genes differentially expressed in response to short- and long-term iron deficiency in both Clark and Isoclark. We are currently using virus-induced gene silencing (VIGS) to silence candidate iron-efficiency genes. We expect this information will aid in developing soybean lines with increased tolerance to IDC.