Genome-wide identification of SAP family genes and characterization of TaSAP6-A1 to improve Cd tolerance in Triticum aestivum L.

Stress Associated Proteins (SAPs) contain A20/AN1 zinc finger domains and, have been proposed to function in various physiological processes such as cold, salinity, drought, heavy metals, damage, and flooding resistance in plants. Here, a total of 131 SAP genes were identified, including T. aestivum (60), T. urartu (10), Ae. Tauschii (16), T. dicoccoides (13), O. sativa (18), and A. thaliana (14). A phylogenetic analysis revealed that the SAPs are clustered into two subfamilies. The TaSAP genes in the collinear region comprised 34 pairs of duplicated genes formed through segmental duplication events. Overexpressing TaSAP6-A1 in wheat enhanced Cd tolerance, whereas knock-down of this gene increased Cd sensitivity. Yeast two-hybrid (Y2H) and bimolecular fluorescent complementation assays (BiFC) demonstrated interaction between TaSAP6-A1 and phenylalanine ammonia-lyase (TaPAL), the first enzyme in the phenylpropanoid pathway. This study provides a valuable reference for further investigations into the functional and molecular mechanisms of the SAP gene family.