Genome-Wide Identification of the PLATZ Gene Family and Its Roles in Stress Responses in Flax (Linum usitatissimum L.) Based on the Telomere-to-Telomere Genome

The PLATZ gene family influences plant growth, development, and responses to both biotic and abiotic stresses. Flax (Linum usitatissimum L.), an important oilseed and fiber crop, has not been extensively studied for its PLATZ genes. In this study, 27 LuPLATZ genes were identified in the recently assembled T2T (Telomere-to-Telomere) flax genome through bioinformatics analyses. Phylogenetic analysis grouped these genes into five subfamilies. Examination of gene structure and motifs showed conserved exon–intron arrangements and similar motif compositions within the same clade. Promoter analysis revealed that most cis-elements are associated with plant hormone responses (such as MeJA and ABA) and abiotic stresses, including anaerobic induction, drought, and low temperature. Duplication analysis identified 33 segmental duplication events, and miRNA target prediction indicated that lus-miR167 is the primary regulator of LuPLATZ genes. Expression profiling based on RNA-seq data showed high expression levels of most LuPLATZ genes in leaves and roots, and qRT-PCR confirmed their stress-responsive expression under cold, drought, and salt conditions, with LuPLATZ14 and LuPLATZ21 significantly upregulated in all treatments. Furthermore, overexpression of these two genes enhanced drought tolerance in yeast transformants.