Transcriptional activator that functions with GLK1 to promote chloroplast development. Acts as an activator of nuclear photosynthetic genes involved in chlorophyll biosynthesis, light harvesting, and electron transport. Acts in a cell-autonomous manner to coordinate and maintain the photosynthetic apparatus within individual cells. May function in photosynthetic capacity optimization by integrating responses to variable environmental and endogenous cues (PubMed:11828027, PubMed:12220263, PubMed:18643989, PubMed:19376934, PubMed:19383092, PubMed:19726569). Prevents premature senescence (PubMed:23459204). Interacts with NAC92. Expressed in cotyledons and rosette and cauline leaves. Expressed at low levels in roots, shoots, flowers and siliques. By light. Repressed by BZR2. Pale green siliques (PubMed:12220263). Pale-green seedlings in double mutants glk1/glk2 (PubMed:23459204). Plants overexpressing GLK2 have a delay in flowering under long days. Truncated C-terminus.