FIGURE 1.

Areas of focus of plant studies seeking to understand root traits related to plant productivity under water shortages and genetic screening of traits to identify their coding. Organism level refers to whole plant traits, organ system to the entire root system (fine and coarse roots, as the shoot system would refer to leaves and stems), organ to single root types (e.g., fine roots), and tissue or cell to single cell types (e.g., xylem or cortical cells). Root traits in black text are traits that have been shown to be related to drought tolerance, and gray italic those that may be associated with drought tolerance but either require more research or have been equivocal.