Non-functional protein probably interfering with the disassembling mechanism of the intact light-harvesting complex of photosystem II (LHCII) in the thylakoid membranes. Responsible for a stay-green phenotype. Not induced during senescence. Up-regulated during dark-induced senescence. Corresponds to one of the seven genes studied by Gregor Mendel in 1866 (PubMed:17204643). The wild type line JI4 has a functional SGR protein (AC A7VLV1) lacking a two amino acids insertion. This protein is involved in the chlorophyll breakdown pathway (Ref.1 and PubMed:18301989). Belongs to the staygreen family.