Putative involvement of <scp>lncRNA</scp> , <scp>miRNA</scp> , and <scp>mRNA</scp> ‐mediated <scp>ceRNA</scp> network regulation in drought priming to enhance drought tolerance in <i>Nicotiana tabacum</i>

Abstract Drought priming enhances drought tolerance by exposing a plant to a previous water deficiency for a specified period in a mild and controlled manner. This study investigated the role of predicted competitive endogenous RNA (ceRNA) regulatory networks, regulating mRNA level due to interaction between long‐noncoding RNAs (lncRNAs) and microRNAs (miRNA), after drought‐priming to improve drought tolerance in Nicotiana tabacum . Therefore, 40‐day‐old plants previously drought‐primed (D) by withholding watering until wilting, then re‐watered, or non‐drought‐primed (CD) were subjected to drought stress and evaluated morphologically, physiologically, biochemically, and transcriptionally compared to well‐watered plants (C). Drought stress caused a significant increase in the total leaf area by 17%, relative water content (RWC) by 32%, ascorbate peroxidase (APX) activity by 23%, superoxide dismutase (SOD) activity by 272%, the shoot length by 8% in the generative stage but a decrease in the shoot length by 33% in the vegetative stage, and a delay in flowering in drought‐primed plants compared to non‐drought‐primed. Eight ceRNA‐networks were predicted to be related to known drought‐responsive genes. Transcriptional analysis revealed the specific regulatory interactions between lnc/miR160, lnc/miR168, lnc/miR172, lnc/miR390s and their competitors PEPC , RD22 , AP2 , F3H genes. miR160 and miR168 along with their predicted targets, PEPC and RD22 , were upregulated, while their lncRNA competitors remained non‐differentially expressed. AP2 and miR172 were downregulated, but lnc172 was upregulated. miR390 and lnc390 antagonistically expressed and regulated F3H . Overall findings contributed to the understanding of the role of priming in alleviating drought effects by creating a ceRNA network‐mediated molecular and enzymatic memory.