Plastid lifecycle

Plastids are never made from scratch: they grow by importing nucleus-encoded proteins through the TOC-TIC translocons and multiply by binary fission, and each cell inherits them from its parent. In green tissue they differentiate into chloroplasts that carry out photosynthesis and much of the cell's lipid, amino acid and cofactor synthesis; they can also become amyloplasts, chromoplasts or etioplasts, and are removed by chloroplast autophagy and other degradation routes. This umbrella module composes the modules for those stages by reference. Protein import and division are required in the green lineage; the photosynthesis modules are optional. The umbrella is written for land plants.

Organelle lifecycle umbrella (see projects/ORGANELLE_LIFECYCLES.md); stage roles and order slots follow the shared skeleton. Scoped to Embryophyta, unlike the eukaryote-wide umbrellas, because the import rule's receptor selectors only hold in land plants (see plastid_protein_import); the division rule is written at Viridiplantae. Read as a satisfiability rule, the umbrella is satisfied when import and division are. Photosynthesis, the light reactions, the Calvin-Benson-Bassham cycle and photorespiration are optional references: non-photosynthetic plastids exist, and those modules are not written as land-plant satisfiability rules. Not yet modelled: plastid gene expression, envelope and thylakoid membrane biogenesis, plastid quality control (the FtsH and Clp proteases) and turnover by chlorophagy or the CHLORAD pathway.