Plant Epigenetic Stress Memory Induced by Drought: A Physiological and Molecular Perspective.

Drought stress is one of the most common stresses encountered by crops and other plants and leads to significant productivity losses. It commonly happens that drought stress occurs more than once during the plant's life cycle. Plants suffering from drought stress can adapt their life strategies to acclimate and survive in many different ways. Interestingly, some plants have evolved a stress response strategy referred to as stress memory which leads to an enhanced response the next time the stress is encountered. The acquisition of stress memory leads to a reprogrammed transcriptional response during subsequent stress and subsequent changes both at the physiological and molecular level. Recent advances in understanding chromatin dynamics have demonstrated the involvement of chromatin modifications, especially histone marks, associated with drought stress-responsive memory genes and subsequent enhanced transcriptional responses to repeated drought stress. In this chapter, we describe recent progress in this area and summarize techniques for the study of plant epigenetic responses to stress, including the roles of ABA and transcription factors in superinduced transcriptional activation during recurrent drought stress. We also review the possible use of seed priming to induce stress memory later in the plant life cycle. Finally, we discuss the potential implications of understanding the epigenetic mechanisms involved in plant stress memory for future applications in crop improvement and drought resistance.