Molecular Stress Physiology of Plants: From Cell-type Specific Regulations to Microbe-Mediated Mitigation

Molecular Stress Physiology of Plants: From Cell-type Specific Regulations to Microbe-Mediated Mitigation

Environmental stresses play crucial roles in crop productivity and survival. Plants evolve different mechanisms of tolerance to cope with the stress effects including physiological, developmental, biochemical, molecular and genetic changes. Plant responses to stress include alterations in signaling components and metabolic adjustments in distinct cell-types of plant tissues. However, each plant cell-type is defined by specific transcriptional, protein, and metabolic profiles that determine its function and responses to stress. Therefore, it is critical to identify the key stress-responsive regulators at cellular levels to better understand the molecular mechanisms of plant responses to individual and combined stresses. On the other hand, the plant microbiome, including bacterial endophytes, has been found to promote plant growth and alleviate host stress. In this work, hybrid poplar trees exposed to drought, salinity, heat, and combination of triple stresses were used to isolate distinct leaf and root cell types using cryo-sectioning and laser-capture microdissection. Then, low-input RNA sequencing, nano-proteomics, and mass-spectrometry imaging approaches were employed to resolve the plant spatial complexity under single and simultaneous occurrence of abiotic stresses. In other work, using a combination of x-ray imaging, spectroscopy methods, and proteomics, we studied the roles of bacterial endophytes in the growth of plants under nutrient-limiting conditions. We reported evidences of endophyte-promoted phosphorus uptake in poplar indicating that certain bacteria are important for nutrient acquisition. Overall, our results provide information that is missing in whole tissue-based analyses, including cell population-specific gene, protein and metabolite profiles that are unique for the distinct cellular layers of poplar leaves and roots. These findings also provide a deeper understanding of the biological relevance of the symbiosis between the plant system and its microbiome.

Environmental stresses play crucial roles in crop productivity and survival. Plants evolve different mechanisms of tolerance to cope with the stress effects including physiological, developmental, biochemical, molecular and genetic changes. Plant responses to stress include alterations in signaling components and metabolic adjustments in distinct cell-types of plant tissues. However, each plant cell-type is defined by specific transcriptional, protein, and metabolic profiles that determine its function and responses to stress. Therefore, it is critical to identify the key stress-responsive regulators at cellular levels to better understand the molecular mechanisms of plant responses to individual and combined stresses. On the other hand, the plant microbiome, including bacterial endophytes, has been found to promote plant growth and alleviate host stress. In this work, hybrid poplar trees exposed to drought, salinity, heat, and combination of triple stresses were used to isolate distinct leaf and root cell types using cryo-sectioning and laser-capture microdissection. Then, low-input RNA sequencing, nano-proteomics, and mass-spectrometry imaging approaches were employed to resolve the plant spatial complexity under single and simultaneous occurrence of abiotic stresses. In other work, using a combination of x-ray imaging, spectroscopy methods, and proteomics, we studied the roles of bacterial endophytes in the growth of plants under nutrient-limiting conditions. We reported evidences of endophyte-promoted phosphorus uptake in poplar indicating that certain bacteria are important for nutrient acquisition. Overall, our results provide information that is missing in whole tissue-based analyses, including cell population-specific gene, protein and metabolite profiles that are unique for the distinct cellular layers of poplar leaves and roots. These findings also provide a deeper understanding of the biological relevance of the symbiosis between the plant system and its microbiome.