Abstract
Seawater intrusion in coastal regions and waterlogging in salinized lands are serious constraints that reduce crop productivity under changing climate scenarios. Under these conditions, plants encounter flooding and salinity concurrently or sequentially. Identification and characterization of genes and pathways associated with both flooding and salinity adaptation are critical steps for the simultaneous improvement of plant tolerance to these stresses. The PROTEOLYSIS 6 (PRT6) branch of the N-degron pathway is a well-characterized process that negatively regulates flooding tolerance in plants. Here, we determined the role of the PRT6/N-degron pathway in salinity tolerance in Arabidopsis. This study demonstrates that the prt6 mutation enhances salinity tolerance at the germination, seedling, and adult plant stages. Maintenance of chlorophyll content and root growth under high salt in the prt6 mutant was linked with the restricted accumulation of sodium ions (Na+) in shoots and roots of the mutant genotype. The prt6 mutation also stimulated mRNA accumulation of key transcription factors in ABA-dependent and independent pathways of osmotic/salinity tolerance, accompanied by the prominent expression of their downstream genes. Furthermore, the prt6 mutant displayed increased sensitivity to ethylene and brassinosteroids, which can suppress Na+ uptake and promote the expression of stress-responsive genes. This study provides genetic evidence that both salinity and flooding tolerance is coordinated through a common regulatory pathway in Arabidopsis.
Highlights
Most commercially important plants are susceptible to high salt levels
We evaluated whether a well-characterized signaling pathway involved in flooding tolerance, the PROTEOLYSIS 6 (PRT6) branch of the N-degron pathway, regulates adaptation to high salt
This study provides genetic evidence that both flooding and salinity tolerance is coordinated through a common regulatory pathway in Arabidopsis
Summary
Most commercially important plants are susceptible to high salt levels. soil salinization is a serious constraint that threatens food security worldwide. Diverse biological roles of the PRT6/N-degron pathway have been revealed through genetic analysis of loss-of-function mutants of prt and other enzymes of this pathway Such roles include the regulation of seed dormancy and germination, seedling establishment, leaf and root development, photomorphogenesis, leaf senescence, and disease resistance as well as flooding/low oxygen tolerance [9,10,11,12,13,14,15,16,17,18,19,20]. We assessed the role of the PRT6/N-degron pathway, a key regulatory process of flooding tolerance, in adaptation to salinity stress in Arabidopsis through physiological and molecular characterization of the prt mutant.
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