Comparative Physiological and Proteomic Analysis of Two Sugar Beet Genotypes with Contrasting Salt Tolerance

Soil
salinity is one of the major constraints affecting agricultural
production and crop yield. A detailed understanding of the underlying
physiological and molecular mechanisms of the different genotypic
salt tolerance response in crops under salinity is therefore a prerequisite
for enhancing this tolerance. In this study, we explored the changes
in physiological and proteome profiles of salt-sensitive (S210) and
salt-tolerant (T510) sugar beet cultivars in response to salt stress.
T510 showed better growth status, higher antioxidant enzymes activities
and proline level, less Na accumulation, and lower P levels after
salt-stress treatments. With iTRAQ-based comparative proteomics method,
47 and 56 differentially expressed proteins were identified in the
roots and leaves of S210, respectively. In T510, 56 and 50 proteins
changed significantly in the roots and leaves of T510, respectively.
These proteins were found to be involved in multiple aspects of functions
such as photosynthesis, metabolism, stress and defense, protein synthesis,
and signal transduction. Our proteome results indicated that sensitive
and tolerant sugar beet cultivars respond differently to salt stress.
The proteins that were mapped to the protein modification, amino acid
metabolism, tricarboxylic acid cycle, cell wall synthesis, and reactive
oxygen species scavenging changed differently between the sensitive
and tolerant cultivars, suggesting that these pathways may promote
salt tolerance in the latter. This work leads to a better understanding
of the salinity mechanism in sugar beet and provides a list of potential
markers for the further engineering of salt tolerance in crops.