You could certainly do it in an E. coli bacteria tomorrow. You'd need on the low end 128 or 256 bits of coding capacity, which you should be able to get out of

You could certainly do it in an E. coli bacteria tomorrow. You'd need on the low end 128 or 256 bits of coding capacity, which you should be able to get out of a few thousand base pairs according to their scheme. Not super easy, but I've made strands that long using only oligos and with a little tinkering you could correct any errors. Now tie that DNA to an antibacterial-resistance gene, stick it in a bacteria, and you can selectively grow only PGP-bacteria nearly indefinitely (with some minor caveats, but yeah). Houseplants are substantially harder for a variety of biochemical reasons including having multiple chromosomes, and more difficult selection protocols, but yeah that should be possible too and made somewhat easier by CRISPR.