Figure 1.

The effects of PPA on aleurone protoplasts and layers. (A) Freshly isolated protoplasts and layers were treated with GA (5 μM), ABA (5 μM), or PPA (50 μM) and secreted α-amylase activity assayed after 48 hr. For protoplasts four types of PPA were used, differing in their acyl chains as denoted, for layers PPA with the acyl chain arachidonoyl/stearoyl was used. The data shows mean ± SEM, n = 3. (B) Western blot analyses show the effect of arachidonoyl/stearoyl PPA on levels of α-amylase, tubulin, and the ABA-induced proteins RAB and ASI. These blots reflect the levels of the proteins in the protoplasts rather than secreted activity assayed in A. Protoplasts were treated for 48 hr, protein extracted, and SDS/PAGE and immunoblotting carried out as described in Materials and Methods. (C) Effect of arachidonoyl/stearoyl PPA on cytoplasmic [Ca²⁺] levels. Protoplasts were treated with either GA for 24 hr and then with PPA (GA then PPA) or ABA (GA then ABA), or freshly isolated protoplasts were treated simultaneously with GA and PPA or GA and ABA.