Your capital gain will be taxable by Iowa, because the property is located in Iowa, and by Missouri, because your resident state can tax all your income. You'll be able to claim a credit on your MO return for the taxes paid to IA, so the net effect is that you won't be double-taxed.
In TurboTax, be sure to complete the non-resident return before the home state return, so that the program can correctly calculate and apply the credit.
In the My Info section, indicate that you had Other State Income from Iowa.