Genomic Generation Cycle Hypothesis for Plants and its Interpretation from the Evolutionary Point of View

Accumulated evidence strongly suggests that the genetic makeup, both nuclear and organellar, in somatic cells undergoes variation at the genome copy number, chromosomal, and primary sequence levels during plant development and in response to the environment. However, it is also known that most cultivars, particularly homozygous pure lines are remarkably reproducible over cycles or generations if their reproduction is through an adapted means, despite the absence of germline cells. Stemming from these observations, I propose the following hypothesis: There is likely an irregular generational cycle, genomic and epigenomic, of the plant genetic makeup. It is at this cycle level that a species or cultivar is relatively stable or reproducible over generations through an adapted reproduction means, such as seed formation and regrowth from the seed in most cereals and vegetables. Individual plants, as well as animals, using very different novel reproduction methods may nonetheless meet well commercial criteria but can carry certain genomic variations inherited from the mother cells in propagation or created during the propagation. Under the already adapted reproduction, the somatic cells in the pipeline towards offspring-production for retaining the genetic makeup in the new generation must be in the reproductive meristems, receive strong screening, and follow the need for reproduction but still allow occasional mutation and transgenerational adaptive responses to occur. The genetic makeup in other somatic cells, such as of vascular tissues and fibrous roots, can be more variable/instable, which is likely critical to plant growth and development.