Lg,
I think we both might be working out of different frames of reference for consciousness if you're suggesting a plant can be alive yet have no consciousness.
In short, I am suggesting that anything that has an element of self awareness has consciousness. Of course there are a range of levels of consciousness. For instance even though a plant may strive towards the sun or respond in a certain way to predators (for instance I vaguely recall that some trees when being attacked by a particular type of ant not only releasing some sort of chemical into their leaves to make them less palatable but also a similar effect was noted in nearby trees that were not currently under attack), you cannot put that on an equal level with the capacity for self rumination the human form of life exhibits.
We may well have a difference in terminology here.
I define consciousness as specifically being mentally aware in such a way that an entity can distinguish clearly between itself (the thing being aware) and all other things and events. This ability appears to have a direct correlation to brain complexity. Some degree of self-awareness has been noted in dolphins, apes, and even elephants. We should also note that a new born child does not possess self-awareness for some time until its brain has sufficiently developed.
I also clearly distinguish between biological life and consciousness. Bio-life can exist without consciousness, and is not dependent upon it. A plant for example is not aware of itself. A plant represents a system that reacts to its environment, much live waves in the ocean react to the motions of the moon and sun, or a hurricane can wreak devastation over populated areas. A hurricane has mass, motion, direction, and reacts to its changing environment (e.g. air pressure, temperature, etc). If we adopt your suggestion for self-awareness as per the plant and trees then we can see that a hurricane is even more advanced but contains no living cells. Does a hurricane posses a soul?
A plant is a system of cooperative sub-components (cells) that form an autonomic entity. Much like a new born child whose immature state can do little more than automatically react to its surroundings according to its hard-wired autonomic sub-systems. The child becomes self aware and develops consciousness as its brain grows but the plant has no such ability.
Even as self-aware humans much of our bodily functions are autonomic. For example you do not consciously direct your digestive system, or control how your liver and kidneys operate. These are subsystems that you depend upon, i.e. groups of specialist cooperative cells that fulfill specific functions. They are not in themselves self-aware or possess consciousness.
The example you give of trees reacting to an invader, etc, are again simple examples of evolved autonomic systems. No consciousness or self-awareness exists in these instances.
I continue to have no comprehension of what you propose a soul might be or what function it might perform based on these real-world observations and scientific studies.
I have equated consciousness here with self-awareness, i.e. self-awareness is the essential characteristic of consciousness that allows us to identify that consciousness exists. As we see with other higher animals, dolphins and apes, it is not a clear black and white boundary, there is some grayness to the transition point, and this correlates directly with brain complexity.
I see no case or justification for proposing that individual cells contain within themselves any degree of consciousness or are in anyway reliant on such a requirement. Neither do I see that you have made any cogent case for such a claim. We have only seen your assertions with no reasoned basis for support.