Very little is known about the genetic basis of seed longevity or how storage conditions and the environment during seed formation influence this trait. Here QTL mapping was used to identify loci controlling seed longevity in M. truncatula during storage at 35°C and 75% RH (accelerated aging, AA) or 65 % RH (moderate aging, MA). Seeds from two recombinant inbred lines derived from the crosses J6 x DZA315.16 and DZA315.26 x DZA 45.6A were produced in two successive years at two green house locations in France (Dijon and Angers). The analyzed parameters were final percentage of germination, speed of germination and percentage of abnormal seedlings after increasing storage time. A total of 29 QTL were identified, with most of the phenotyped parameters colocating on 10 chromosome regions. Only two QTL were stable,between the production year, explaining 32% and 14% of the variation. Seven chromosome regions were associated with QTLs of MA and five regions were associated with AA. Only four of them were co-locating, including the stable QTLs. This suggests that the nature of deteriorative conditions depends on the life history of the seed development, but also vary according to the temp/WC combination set during storage. Next, using a 2-D electrophoresis gel analysis, we identified two PQLs controlling the amount of SNF4b, a subunit of a SnRK1 complex known to be involved in seed longevity. A trans PQL co-located in the same interval as the stable QTL for longevity both under MA and AA. To identify candidate genes responsible for the observed phenotypes, a co-expression analysis of MtSNF4b and subsequent in silico mapping was performed and resulted in the identification of a ABI5 within the mapping interval of the PQL. To validate ABI5 as a key regulator of seed longevity, two Tnt1 insertion mutants were obtained, back-crossed and phenotyped. Mature abi5 seeds exhibited a 2-fold decrease in longevity. Molecular attributes thought to confer longevity such as LEA proteins and non-reducing sugars were also affected in abi5 seeds. These results suggest that ABI5 plays an important role as a key hub regulating seed longevity.