Multiple stress responses and adaptations

Farmers and breeders know that combinations of biotic and/or abiotic stresses in the field (e.g. disease and drought or high-light and cold) cause the greatest losses to crop productivity worldwide. Responses and tolerance to stress combinations are rarel y addressed in genomics research because two or more stresses are more difficult to simulate than a single stress. In addition, bioinformatic tools for combinatorial analyses required for such systems biology are only now being developed for plants. There fore, we need to know more about, and develop tools to analyze, the effects of multiple stresses on plants. ~300 cellular stress genes are conserved in all organisms to defend or repair vital macromolecules against environmental forces. However, stress re sponse genes also evolve rapidly as organisms adapt to environments. Thus, antifreeze proteins evolved separately in different phyla, and half of the ~70 osmo-responsive genes in Arabidopsis are plant-specific. Clearly, we can only understand the full com plement of stress responses by comparing data on single stresses with data on multiple stress responses. Such data will be relevant to agronomy, and provide tools to answer basic questions about signaling crosstalk in systems biology.