Unique Aspacts of Stress Combination
Recent studies from our labs demonstrated that the molecular, biochemical and metabolic response of plants to a combination of drought and heat stress is unique and cannot be directly extrapolated from the response of plants to each of these different stresses applied individually. Our major findings are summarized below:
- Physiological characterization revealed that the stress combination has several unique aspects combining high respiration with low photosynthesis, closed stomata, and high leaf temperature (Fig. 3A).
- Transcriptome profiling revealed that the stress combination requires a unique acclimation response involving over 770 transcripts, not altered by drought or heat stress (Fig. 3B). Some of these encode transcription factors such as MYB.
- Metabolic profiling identified several unique metabolites that specifically accumulate during the stress combination (Fig. 3C; ongoing work).
- Proteomic analysis identified 53 proteins that specifically accumulate in plants during the stress combination.
- A synergistic relationship was identified between drought- and heat-specific pathways co-activated in plants during a combination of drought and heat stress (i.e., the transcriptional co-activator MBF1c). This relationship was tested with MBF1c gain- and loss-of-function mutants.
- A key point of antagonistic relationship was identified between drought- and heat-specific pathways co-activated in plants during a combination of drought and heat stress (i.e., proline accumulation; 2). This point was tested with mutants altered in proline accumulation.
- Soybean plants overexpressing MBF1c were developed. They show enhanced seed production when grown under heat stress conditions (work in progress).
Fig. 3. Physiological and molecular characterization of tobacco and Arabidopsis plants subjected to a combination of drought and heat stress. A. Physiological characterization of tobacco and Arabidopsis plants presented as % of control to summarize data from tobacco and Arabidopsis (1,2). B. and C. Venn diagrams summarizing transcriptome (B) and metabolome (C) profiling of Arabidopsis plants subjected to drought, heat or a combination of drought and heat (after 2). Heat and drought+heat were profiled based on similar leaf temperature.
