Figure 6.

Antagonistic Relationship between OST1 (SnRK2.6) and FyPPs.

(A) Germination and growth of Col, ost1, F3DN, and ost1 F3DN seeds and seeds from self-pollinated f1^−/+ f3 and f1^−/+ f3 ost1 plants incubated on GM plates with or without ABA. Seeds were incubated under white light for 5 d.

(B) Germination of Col, ost1, F3DN, and ost1 F3DN seeds and seeds from self-pollinated f1^−/+ f3 and f1^−/+ f3 ost1 plants. Seeds were grown under white light for 5 d on GM plates with the indicated concentrations of ABA. Germination was determined with an average of >100 seeds from three independent experiments. Values are means ± sd.

(C) Greening of Col, ost1, F3DN, and ost1 F3DN seeds and seeds from self-pollinated f1^−/+ f3 and f1^−/+ f3 ost1 plants incubated on GM plates with (1 μM) or without ABA treatment for 5 d. Greening was determined with an average of >100 seeds from three independent experiments. Values are means ± sd. Asterisks indicate the levels of statistical significance as determined by Student’s t test: *P < 0.01 versus Col.

(D) Immunoblot analysis of ABI5 accumulation in kinase- and phosphatase-deficient mutants. In the absence of ABA, there was no detectable ABI5 protein in Col, ost1, f1^−/+ f3, F3DN, f1^−/+ f3 ost1, and F3DN ost1 seedlings. After ABA treatment (1 μM, 8 d), ABI5 (indicated by the arrows) hyperaccumulated in seeds of self-pollinated f1^−/+ f3 or F3DN lines, in contrast with the reduced accumulation of ABI5 in seeds of self-pollinated f1^−/+ f3 ost1 plants and F3DN ost1 lines. There was no detectable ABI5 protein in Col and ost1 seedlings at this stage. The arrowhead indicates the nonspecific band recognized by the ABI5 antibody. Arrows indicate the ABI5 bands. RPT5 was used as a loading control. A total of 100 μg protein was loaded for each lane.