I do not know of a Roma tomato resistant to blossom end rot but I do know you can prevent this disease with consistent watering and making sure you use a complete plant food that contains both macro and micro nutrients. I mix Osmocote into the soil at planting time and than check the soil daily to make sure it is moist but not wet. Poke a finger into the soil and water when the top one inch is dry to the touch. Blossom End rot is not really a disease, it is more a condition that develops on tomatoes when the soil is allowed to dry out and than is soaked with water. This results in a lack of calcium available to the tomato. Keep growing, Marianne Binetti