Probably not. The plant may well be budded, meaning a bud of the rose you saw flowering was inserted under the bark of a rooted piece of another rose used to provide the desired rose with more vigorous roots. IF you succeeded in raising anything from the roots, it would likely be the rose used to provide the roots, the 'root stock', and not the rose you saw flowering. It's a shame you've already dug the plant up as you could probably have posted photos of the white fungus you worried about and found out what to do to correct it, leaving the rose in place and likely flowering this year. Your best bets now are to try rooting stems from the rose to produce an own root plant of it, and/or replanting it and mounding it under a mound of damp soil to keep it cool, dark and damp which will encourage it to produce a new root system and begin supporting itself. If you're thinking of doing that, you should prune the top of the plant to balance it with what's left of the roots, replant, then mound it with soil so that only an inch or so of each cane remains out in the sun and air. Keep the mound watered so it can provide moisture to get back into the plant and support it while it produces new roots. You should see new growth beginning to push from those cane tips in a few weeks, if it works. Then, you can gradually remove the mound of soil, exposing more of the plant slowly to allow it to harden off against the hotter, drier air and sun, until you finally remove the remaining mound of soil. The rose should be growing properly by then. Good luck!
