Figure 3.

The level of AtPRP3/GUS expression is modulated during Arabidopsis root development. AtPRP3/GUS seedlings were grown as indicated below, and then harvested and whole seedling extracts analyzed fluorometrically for GUS activity. A, Effect of ethylene and auxin on AtPRP3 expression. Transgenic AtPRP3/GUS seedlings were grown for 3 d and then transplanted onto medium containing no effectors (control), 5 μm ACC, 25 nm α-NAA, 20 μm AVG, 20 μm AVG + 80 μm ACC, or 20 μm AVG + 100 nm α-NAA for an additional 2 d of growth. The sd for AtPRP3/GUS expression in AVG-treated seedlings was ±6. B, Effect of Ca²⁺ and light on AtPRP3 expression. Transgenic AtPRP3/GUS seedlings were grown for 3 d before being transplanted onto medium with or without Ca²⁺ for an additional 2 d of growth. Alternatively, seedlings were grown for 3 d under continuous white light or in complete darkness. The control level of GUS activity represents that measured in light-grown seedlings in the presence of Ca²⁺. C, Influence of root hair mutant backgrounds on AtPRP3 expression. Transgenic lines of Columbia, ttg, and rhd6 seedlings expressing the AtPRP3/GUS construct were grown for 4 d under continuous white light. The sd for AtPRP3/GUS expression in the rhd6 mutant background was ±1.5.