My convention is to quote the submitted article with quotation marks, like this:

"SQL was invented in the 70s for business analysts to write reports without having to go bug the programmers."

And then I quote the parent comment with the HN convention of preceding and following the quoted text with asterisks to italicize it, like this:

Please quote with '>', not by indenting.

But, yeah, definitely not by indenting.

Yeah, I didn't mean to really enforce '>' so much as to discourage the indenting (which is causing annoying horizontal scrolling on my side of things).