GEOapplication/xmlftp://ftp.ncbi.nlm.nih.gov/geo/series/GSE320nnn/GSE320089/primaryOK200TranscriptomicsArabidopsis thalianaExpression profiling by high throughput sequencinghttps://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE320089GEOGSEfalseEmbryonal degreening and seed longevity require plastid LEA proteinsSeeds enable plant embryos to endure extended periods and environmental extremes. Desiccation-tolerant, orthodox seeds acquire stress resistance during maturation, before metabolic quiescence. Coordinated disassembly of thylakoids and chlorophyll degradation leads to embryo degreening, a hallmark of orthodox seed maturation. While degreening is under hormonal control, our understanding of the molecular players involved and its physiological significance remains incomplete. By serendipity, we observed a stay-green seed phenotype in an Arabidopsis mutant lacking two LATE EMBRYOGENESIS ABUNDANT (LEA) proteins, LEA42 and LEA48, which we identified as the dominant LEA proteins in seed mitochondria and plastids. Using lea48xlea42 as a model for impaired LEA function in seed mitochondria and plastids, we used proteomic, transcriptomic, and transmission electron microscopy analyses which jointly indicate incomplete thylakoid degradation. Fresh lea48xlea42 seeds were unaffected in germination, but were impaired in germination after high-temperature/high-humidity ageing. Genetic complementation by LEA expression in either the mitochondrion or plastid revealed longevity support is linked to plastidial, not mitochondrial, LEA. Illumination of mature dry seeds (“light ageing”) reduced longevity, providing a physiological framework for embryo de-greening. Our data identify a role for LEA proteins in remodelling seed plastids before desiccation and highlight LEA-dependent embryo degreening as a decisive contributor to seed longevity.2026/09/12GSE320089GSM9533752GSM9533751GSM9533750GSM9533745GSM9533749GSM9533748GSM9533747GSM953374634608320089Arabidopsis thaliana