Long-Term Salinity-Responsive Transcriptome in Advanced Breeding Lines of Tomato.

Area of Science:

• Plant Science
• Genetics
• Molecular Biology

Background:

• Soil salinity and freshwater scarcity are major global constraints on plant productivity.
• Tomato (Solanum lycopersicum) is moderately sensitive to salinity, impacting crop yields.
• Understanding long-term salt tolerance mechanisms in tomato is crucial for breeding and genetic engineering.

Purpose of the Study:

• To identify salinity-responsive genes in tomato controlling long-term salt tolerance.
• To compare gene expression and physiological responses between salt-tolerant and susceptible tomato genotypes under salinity stress.
• To provide insights for tomato breeding programs aiming to enhance salt tolerance.

Main Methods:

• Holistic approach using RNA sequencing (RNA-seq) to analyze gene expression.
• Measurement of physiological and agronomic traits in two tomato breeding lines (L46 and L56).
• Application of long-term salinity stress (9.6 dS m⁻¹).

Main Results:

• Salt-tolerant genotype L56 showed significant up-regulation of known and novel differentially expressed genes (DEGs) associated with salinity tolerance.
• L56 exhibited a high salt tolerance index (81%) and enhanced expression of CBL-interacting kinase and SALT OVERLY SENSITIVE paralogs.
• Both genotypes upregulated ROS-detoxifying enzymes and ROS-scavenging proteins, but L56 demonstrated more effective downstream stress signaling.

Conclusions:

• Genotype L56 possesses a genetically robust network for salt tolerance, effectively conveying stress signals.
• Genotype L46, while susceptible, shows potential genetic background for salt tolerance.
• Both L56 and L46 offer valuable genetic resources for future tomato breeding programs focused on salinity adaptation.