let’s say could rice or another highly productive crop be altered so that it would provide complete protein for the human diet?
How hard is it to make an organism to produce new proteins anyway? How about humans, could they be modified to produce all amino acids by themselves so that “complete protein” would have become immaterial?
From Wikipedia:
“Some foods contain all the essential amino acids on their own in a sufficient amount to qualify as a “complete protein”. Complete protein foods that also obtain the highest possible PDCAAS score of 1.0 are certain dairy products (including whey), egg whites, and soy protein isolate. Other foods, such as amaranth, Aphanizomenon flos-aquae[citation needed], buckwheat, hempseed, meat, poultry, soybeans, quinoa, seafood, and spirulina also are complete protein foods, but may not obtain a PDCAAS score of 1.0.”
Have you researched any of these ideas you come up with before posting here?
The OP didn’t ask whether this is a commercial plan and didn’t dispute whether complete proteins exist. The question is whether an incomplete protein can be made complete by genetic engineering. I don’t know that answer and it’s an interesting question.