Reversing the Irreversible: Reshaping Plant Growth upon Recovery from Severe Stress - Project Summary Plants in nature and rain-fed agriculture experience cycles of drought and rehydration. Improving how plants respond to drought has been a major target of plant scientists worldwide, yet generating drought tolerant varieties remains a challenge. The physiological and molecular responses to drought have been largely explored, however, what occurs upon rehydration is poorly understood. Thus, focusing on the transcriptional response to rehydration following drought could yield novel scientific discoveries which will protect global food security. By applying single-cell multiomic analyses to Arabidopsis during long-term recovery from severe stress, this project will generate several comprehensive datasets that provide insights into the transcriptional programs of stress recovery. The approach to focus on drought recovery yielded three major discoveries: (1) The process of drought recovery is genetically active with >3000 recovery specific genes found. (2) Numerous immunity genes are induced early during the recovery process. (3) Recovery from moderate drought activates immune-genes and increases plant resistance to pathogenic infection. This work laid the foundation of the currently ongoing work to unravel mechanisms of stress recovery. Once establishing that recovery is a process that can be studies and improved without impairing drought response, and identifying thousands of recovery specific genes, it is now possible to interrogate the mechanisms leading to irreversible transcriptional changes leading to devastating results on plant development and productivity. In the proposed career development strategy, during the K99 phase, the candidate will gain independence in single cell multiomic technologies and epigenetics, which will be important for the R00 phase and future career goals to open her independent lab, and unravel the process of stress recovery. This study tests several hypotheses: in Aim 1 the hypothesis that severe stress leads to irreversible post-recovery developmental changes will be tested. In Aim 2, the hypothesis that intragenerational epigenetic changes cause irreversible changes in gene expression after severe stress will be tested. These changes can be regulated by either DNA methylation, or changes in chromatin states that are anchored in histone modifications during severe stress. Aim 3 will focus on characterizing recovery master regulators. The hypothesis that calmodulin-binding transcription activator 1 (CAMTA1), and CAMTA5, have a key role in drought recovery, and that activating these genes will show improved recovery in Arabidopsis plants. The proposed research pioneers the field of stress-recovery studies and deepens our insights of the power of intragenerational epigenetics probing how lifestyle and environment shape our genetic outcomes using plants as a robust model. These discoveries will significantly advance our comprehension and control of human health and disease. Finally, such insights are vital for the development of plants robust against climate-induced environmental stressors.
