I published three papers in peer reviewed journals during my undergraduate days as first author. See http://www.paraschopra.com/publications/

I don't think PhD is a pre-requisite or even makes much difference in peer review process. Of course, with a PhD you would have better experience and possibly better research. Many of the good journals remove names and adresses before sending for a review, so it is a blind peer review where holding a PhD degree or not does not make much difference.