Identification of Reliable Reference Genes for qRT-PCR Normalization in Tomato Genotypes with Contrasting Salinity Tolerance

Salt-tolerance improvement of tomatoes is largely a task of modern selection and plant molecular genetics because of cultivation on dry and irrigated lands under salt stress. To reveal the salt resistance gene, we need quantitative real-time polymerase chain reaction (qRT-PCR) normalization through reference genes analysis. Sometimes, housekeeping gene expression changes in response to various stress factors, especially salinity. In this manuscript, we evaluated expression changes of elongation factor 1α X53043.1 (EF1α), actin BT013707.1 (ACT), ubiquitin NM_001346406.1 (UBI), nuclear transcript factor XM_026030313.2 (NFT-Y), β-tubulin NM_001247878.2 (TUB), glyceraldehyde-3 phosphate dehydrogenase NM_001247874.2 (GAPDH), phosphatase 2A catalytic subunit NM_001247587.2 (PP2a), and phosphoglycerate kinase XM_004243920.4 (PGK) in salt-sensitive Solanum lycopersicum L. YaLF line and salt tolerance Rekordsmen cv. under 100 mM NaCl. We also suggested potential correlations between relative water content (RWC), ion accumulation, and reference gene expression in tomato genotypes with contrasting salinity tolerance. We used geNorm, NormFinder, BestKeeper, ∆Ct, and RefFinder algorithms to establish a set of the most reliable tomato candidate genes. The most stable genes for YaLF tomatoes were ACT, UBI, TUB, and PP2a. Despite differences in ranks, the NFT-Y was present in Rekordsmen’s stable set.