Characterization of two poplar homologs of the GRAS/SCL gene, which encodes a transcription factor putatively associated with salt tolerance

Soil salinity is one of the most severe abiotic stress in the Vojvodina region (Serbia), and efforts are being undertaken to enhance the salt tolerance of economically important poplar clones. We screened nucleotide diversity in candidate genes (CG) in several poplar clones to search for associations with salt stress tolerance. As plant-specific GRAS/SCL transcription factors (TFs) play a relevant role in abiotic stress resistance, two poplar homologs of GRAS/SCL TFs were chosen to differentiate the species background with respect to salt tolerance. A BLAST search of the Populus trichocarpa genome using the P. euphratica gene GRAS/SCL TF_GH611858 sequence allowed the identification of two putative orthologs on Scaf_5 and Scaf_7, with identities of 100% and 94%, respectively. Primers were designed in shared, identical sequences of Scaf_5 and Scaf_7 to amplify fragments of GRAS/SCL TF orthologs in four salt-tolerant poplar clones economically important to Serbia. The primers spanned regions where single nucleotide polymorphisms (SNPs) were present in the P. trichocarpa gene, thereby increasing the probability of distinguishing Scaf_5 and Scaf_7 orthologs in the four clones. Alignments and analyses of the gene fragments revealed that both orthologs were representative of the genetic diversity between different poplar clones, and the identified SNP markers differentiated the four poplar clones with respect to salt tolerance.