Missing optional resume in graduate application The department I am applying to doesn't explicitly require a resume (and doesn't even recommend it), but there is an item named "resume" in the "supplemental material" dropdown menu which I have overlooked. I realized that I didn't upload the resume only after the application has been submitted. I have contacted the admission office, but the auto-response says "We cannot update submitted applications with new SOP or CV or other information."

There is some information in my resume which isn't mentioned in the SOP, e.g. my experience as a teaching assistant. While I have requested a professor from my home university to include the TA experience in his recommendation (because I am his TA), it is said that most institutions in the U.S. don't read letters from Chinese professors. Besides, I suppose a resume serves a nice overview of my previous preparation, so I feel like the absence of a resume is going to hurt the probability I get admitted. On the other hand, there must be some reasons why the resume is made optional, unlike most institutions.

Should I be concerned? Is there anything I can do at this point?
It seems as if you have done all you could. If they won't accept supplementary material, then they won't. I'm not sure about the comment on not reading letters, though. It seems like it would be a flaw in the system as long as the letters are in (readable) English. 

If you get past initial screening you can raise such thing in interviews or in future correspondence, of course. 

And, take more care in the future, of course, though it doesn't help at this moment.