Contrasting response of twoLotus corniculatusL. accessions to combined waterlogging-saline stress

Abstract

AbstractWaterlogging and salinity impair crops growth and productivity worldwide, being their combined effects larger than the additive effects of both stresses separately. Recently, a newLotus corniculatusaccession has been collected from a coastal area with a high frequency of waterlogging-saline stress events. This population is diploid and has potential to increase nutritional values ofLotuscultivars used as forages. Due to its environmental niche, we hypothesize that this accession would show a better adaptation to combined waterlogging-saline stress compared to another commonly used tetraploidL. corniculatus(cv. San Gabriel). Shoot and root growth under waterlogging, salinity and combined waterlogging-saline treatments were addressed, together with chlorophyll fluorescence and gas exchange measurements. Results showed that salinity and waterlogging effects were more severe for the tetraploid accession, being the differences larger under the combined stress condition. In addition, Na+, Cl−and K+concentrations were measured in young and old leaves, and in roots. A larger accumulation of Na+and Cl−was observed under both saline and combined stress treatments for the tetraploidL. corniculatus, for which ion toxicity effects were evident. The expression of theNHX1andCLCgenes, coding for Na+and Cl−transporters respectively, was only increased in response to combined stress in the diploidL. corniculatusplants, suggesting that ion compartmentalization mechanisms were induced in this accession. As a conclusion, the recent characterizedL. corniculatusmight be used for the introduction of new tolerant traits to combined stresses, in otherLotusspecies used as forage.