Biogenic signals from plastids and their role in chloroplast development

Abstract

Plant seeds do not contain differentiated chloroplasts. Upon germination the seedling, thus, need to gain photoautotrophy before storage energies are depleted. This requires the coordinated expression of photosynthesis genes encoded in nuclear and plastid genomes. Chloroplast biogenesis needs to be additionally coordinated with the light regulation network that controls seedling development. This coordination is achieved by nucleus-to-plastid signals called anterograde and plastid-to-nucleus signals coined retrograde. Retrograde signals sent from plastids during intial chloroplast biogenesis are also called biogenic signals. They have been recognized as highly important for proper chloroplast biogenesis and for seedling development. The molecular nature, transport, targets and signalling function of biogenic signals are, however, under debate. Several studies disproved the involvement of a number of key components that were at the base of initial models of retrograde signalling. New models now propose major roles for a functional feedback between plastid and cytosolic protein homeostasis in signaling plastid dysfunction as well as the action of dually localized nucleo-plastidic proteins that coordinate chloroplast biogenesis with light-dependent control of seedling development. This review provides a survey of the developments in this research field, summarizes the unsolved questions, high-lights several recent advances and discusses potential new working modes.

Proximity labelling allows to study novel factors in chloroplast developmenta

“…Mair and colleagues elegantly showed that by using cell line specific promoters for bait-TID constructs populations of FAMA transcription factor vicinal proteins are determinable within the guard cell progenitor lineage (Mair et al, 2019) in vivo in the context of the whole plant. It is now well established, that plastids are highly dynamic organelles, able to differentiate into numerous specialised forms within a tissue dependent context (Liebers et al, 2022). By expressing plastid targeted TID constructs under control of cell line-specific promoters it will be possible to follow bait proxiome changes specifically inside plastids as they are embedded in their endogenous plant context.…”

Plastid double-strand RNA transgenes trigger small RNA-based gene silencing of nuclear-encoded genes

“…The ability to now silence plant nuclear genes from the plastid enables engineering of an array of traits previously unavailable to plastid transformation technology, including metabolic processes, biomass, and grain yield (Mansoor et al, 2006;Kamthan et al, 2015;Saurabh et al, 2014). The results reported here also add a new potential pathway for chloroplast-to-nucleus signaling that has not been previously considered (reviewed in Jan et al, 2022;Liebers et al, 2022).…”

Systematic analysis of photo/sko-regulated germination and post-germination development of shallow photodormant seeds in Nicotiana tabacum L.

“…Light is an important signal factor that involved in regulating of chloroplast biogenesis during post-germination development. It requires the coordinated expression of chloroplast biogenesis genes encoded in nuclear and plastid genomes ( Liebers et al., 2022 ). PHYB are activated by light to promote the degradation of PIF3, which represses the nuclear-encoded components of the plastid transcriptional machinery required for transcription of the plastid-encoded photosynthesis genes ( Dubreuil et al., 2017 ).…”