Salt Biomarkers in Advanced Tomato Lines

Tomato advanced breeding lines, produced and improved using selection and selfing from commercial cultivars for six consequent generations, were investigated for potential salt stress responsive genes as biomarkers in breeding programs. Four tomato lines (L46, salt susceptible; L56, salt tolerant; L66, intermediate salt tolerant; along with BL_1076, an AVRDC salt tolerant line  were grown in soil in a fiberglass greenhouse. Two water treatments were applied (control, 0.5 dS m-1 and high salinity 9.6 dS m-1,) through drip irrigation system. Leaves were collected for total RNA isolation. Labeled RNA from three biological replicates were applied into tomato Affymetrix microarrays. Differential tomato expression profiling was analyzed between all lines. Several responsive genes were uniquely up- or down-regulated for each tomato line, which were confirmed with real-time PCR. The salt responsive genes TAS14, type-a response regulator, calmodulin binding and MYB transcription factor were up-regulated in stressed lines L46, L56, L66 and BL_1076, respectively. WRKY was up-regulated in L56, L66, and BL_1076, while NAC domain and ethylene-responsive factor proteins were prominent in L56 and L66. These salt biomarkers could potentially be utilized during tomato breeding process and aid in pyramiding desired traits.