A Synteny Conserved TATA Binding Protein 2-associated Long Intergenic Non-coding RNA Influences Leaf Development and ABA Response in <i>Arabidopsis thaliana</i>

Long non-coding RNAs are molecules with regulatory potential involved in many biological processes of plants. Despite their significant role, only a limited number have been studied in detail. Here, we describe at the molecular and bioinformatic levels a TBP2-associated long intergenic non-coding RNA (TALIR) encoded upstream of TATA-binding protein 2 (TBP2) of Arabidopsis thaliana. Downregulation of TALIR leads to plants with reduced leaf and rosette size, as well as decreased lateral root density. The expression of TBP2 in talir mutant lines is increased, which affects the timing of expression of MIR396 and GRF2, as well as MIR156 and SPL9. Therefore, these dysregulations may, in part, contribute to the altered leaf size observed. Transcriptional evidence from TBP2 loci suggests the presence of a putative TALIR ortholog gene conserved across the Brassiceae, Eutremeae, and Camelineae tribes at the DNA sequence and synteny level. Furthermore, TALIR is upregulated upon ABA and NaCl treatments in WT plants, whereas talir mutants exhibit insensitivity to ABA during germination. Together, these findings expand current knowledge of lncRNAs and provide new insights into the regulation of MIR396 and MIR156 in the control of leaf growth. Further, the evolutionary conservation of TALIR among tribes within the Brassicaceae family suggests a conserved functional role in this group of plants.