Narrow-leafed lupin (Lupinus angustifolius L.) functional identification and characterization of the aldehyde dehydrogenase (ALDH) gene superfamily

Abstract

Aldehyde dehydrogenases (ALDHs) constitute a NAD(P)+-dependent superfamily of proteins, which catalyze the irreversible oxidation of aldehydes molecules to non-toxic carboxylic acids. This superfamily in legume seeds has a primary role in oxidative stress response under biotic and abiotic stresses as desiccation, cold, salinity, and heat shock factors that largely affect seed germination and seedling growth.Up to date only a study has been dedicated to identify and characterize the complete ALDH superfamily in a legume crop, Glycine max, and other few partial studies focusing on their sequence cloning in pea, and fenugreek, despite the importance of legume crops for food sustainability. The consecution of the narrow-leafed lupin (NLL) (Lupinus angustifolius L.) genome sequencing project have resulted in the identification of ALDH genes that still need to be comparatively analyzed for systematic identification and ALDH gene families functional characterization.In this study, nineteen unique ALDH sequences that encode for 10 ALDH families were identified in L. angustifolius. 5 additional ALDH families (ALDH5, ALDH6, ALDH12, ALDH18, and ALDH22) are present in this specie in comparison to Glycine max. Phylogenetic analysis showed that ALDHs were split into 11 clades containing at least one ALDH gene of NLL. The relationship among families is quite well conserved between legume species and among monocot and dicot plants. Structure–functional analysis of ALDH5 and ALDH6 showed a catalytic mechanism which involved C330–E427 couple, and C320/R143-R319, respectively in a specific molecular (catalytic) environment. The structure–functional analysis identified potential neo-functionalities only in families ALDH2C4 and ALDH7B4.Overall, this study reveals new insights into the functional–structure features and evolution of ALDH gene families, particularly concerning NLL, a legume crop. These ALDH functional identification and characterization are valuable in molecular breeding strategies applied to legume for improvement of stress tolerance and yield.