Figure 1.

The origin of mitochondria and chloroplasts, as modified prokaryotes that have become plant organelles [8], the endosymbiotic relationship between chloroplast, mitochondrion, and plant itself, and the symbiotic relationships between the beneficial microbes and the host plant. Beneficial microbes include plant growth promoting bacteria and fungi. The shelter and habitat created by the plant host provide a regulated environment and energy source, enhancing the survival of the symbionts and endosymbionts.