Dehydration stress memory genes of two wheat landraces (Triticum turgidum L. var. durum).

Pre-exposing plants to diverse a biotic stresses including drought may alter their physiological and transcriptional responses to a subsequent stress, by improving resistance to future exposures, these observations have led to a concept of "stress memory", implying that during subsequent exposures plants provide responses that are different from those during their first encounter with the stress. To asses epigenetic modulation of drought responsive genes (DRGs) in durum wheat (Triticum turgidum L. var.durum), the landraces Hourani27 and Omrabi5 seedlings were exposed to two sequential dehydration treatments S1(first dehydration stress) and S3(second dehydration stress). Differential DRG expression was revealed by quantitative PCR (qPCR). The data was calibrated by the house keeping gene actin. In Hourani 27, the ERF/AP2memory gene was up-regulated later in S3 (4.12 fold) compared to S1, while expression level was similar between S1 and the control ([=/+] W= S1 < S3). This is a type of memory DRGs called the later-responsive. In the contrary, Omrabi5 showed gene induction in S1 (1.76 fold) followed be decline in S3 (1.13 fold) compared to S1 ([+/-], which is a classical memory DRG (W S1 S1 S3).The results demonstrate an evidence of epigenetic memory of DRGs in durum wheat as it modulates gene expression patterns. The gene expression behavior varies from a genotype to another. Omrabi 5 is presumably more drought resilient than Hourani 27 for the investigated DRGs.