We can develop plants that are more resistant to pathogens, such as fungus, and bacteria, or bugs, insects. And we can make plants that are more nutritious, however with no access to fresh greens with do not have food security and as such we will not have it if our plants are damaged or stolen. Shrubs and plants have played a role in home and property defense for literally hundreds of years. People have used them to keep livestock contained, to keep predatory carnivorous animals out, for hedging purposes, or for defense against attacks from other people. But of course, that was then. Now we can build fencing, use of extreme measures like razor wire or electrified fences can be used, but the are plants that can be used in addition.
Thorny brush and thickets deter intruders, A simple hedgerow of thorny thickets may not seem like much, but in reality, it can go a long way toward discouraging a unwelcome visitor. Plant some thorny bushes in front of fences and in the corners where someone is more likely to climb over, add some to the access points like windows. It will make an intruder think twice about following through with their plans. It has the ability to inflict grievous physical injuries and infections on them if they are stupid enough to proceed anyway.