Transcriptome analysis of salt-sensitive and tolerant genotypes reveals salt-tolerance metabolic pathways in sugar beet

Soil salinization is a common environmental problem that seriously affects the yield and quality of crops. Sugar beet (Beta vulgaris L.), one of the main sugar crops in the world, shows a strong tolerance to salt stress. To decipher the molecular mechanism of sugar beet under salt stress, we conducted transcriptomic analyses of two contrasting sugar beet genotypes. To the best of our knowledge, this is the first comparison of salt-response transcriptomes in sugar beet with contrasting genotypes. Compared to the salt-sensitive cultivar (S710), the salt-tolerant one (T710MU) showed better growth and exhibited a higher chlorophyll content, higher antioxidant enzyme activity, and increased levels of osmotic adjustment molecules. Based on a high-throughput experimental system, 1714 differentially expressed genes were identified in the leaves of the salt-sensitive genotype, and 2912 in the salt-tolerant one. Many of the differentially expressed genes were involved in stress and defense responses, metabolic processes, signal transduction, transport processes, and cell wall synthesis. Moreover, expression patterns of several genes differed between the two cultivars in response to salt stress, and several key pathways involved in determining the salt tolerance of sugar beet, were identified. Our results revealed the mechanism of salt tolerance in sugar beet and provided potential metabolic pathways and gene markers for growing salt-tolerant cultivars.