Using transcriptomics to assess plant stress memory

A previous stress exposure may result in a faster or stronger response when plants are challenged again by a stress event. This capacity of plants to remember a past stress and to respond in a different way to multiple stress exposures is called memory response. Despite the mechanisms promoting the plant memory response to abiotic stresses are not completely elucidated, a growing body of evidence has pointed to chromatin remodeling as an important memory mechanism. Additionally, transcriptomic studies have helped to clarify the transcriptional memory types and relevant functional classes of genes and pathways that potentially exhibit a memory behavior. This review focuses on the main concepts related to plant memory responses to abiotic stresses, especially drought which is by far the major environmental stress impairing crop production. We also review the main advances on the mechanisms underlying the plant stress memory responses such as the role of ABA and chromatin remodeling mechanisms. The most recent advances promoted by transcriptomic approaches are also highlighted.