Figure 5.

The rpn12a-1 Mutant Has Decreased Sensitivity to the Cytokinins Kinetin, BA, and 2iP.

(A) Shoot growth inhibition and chlorosis induced by kinetin is stronger in wild-type (WT) than in rpn12a-1 seedlings. Plants were germinated and maintained for 14 days on 0.1 μM kinetin.

(B) Inhibition of shoot growth of wild-type and rpn12a-1 seedlings by a range of kinetin concentrations. Seedlings were germinated in the absence of kinetin and then transferred to medium containing the indicated kinetin concentrations. After 21 days, the mean fresh weights of rosettes from 10 seedlings were determined (±sd). FW, fresh weight.

(C) The rpn12a-1 mutation alters the effect of kinetin on root elongation. Seeds were germinated on growth medium, and after 4 days seedlings were transferred to plates containing 0.2 μM kinetin. The red arrowheads indicate root tips after an additional 4 days of growth.

(D) Effect of a range of kinetin concentrations on root elongation. Wild-type and rpn12a-1 seeds were germinated on growth medium, and after 4 days seedlings were transferred to plates containing the indicated kinetin concentrations. After an additional 14 days of growth, the mean root lengths of 10 plants were determined (±sd).

(E) The promotion of root hair formation and elongation by kinetin is reduced by the rpn12a-1 mutation. Seeds were germinated on growth medium. After 4 days, seedlings were transferred to medium containing 0.2 μM kinetin and grown for an additional 4 days.

(F) Promotion of deetiolation by BA is delayed by the rpn12a-1 mutation. Wild-type and rpn12a-1 seedlings were grown for 28 days in the dark in the presence or absence of 20 μM BA.

(G) The induction of greening and shoot formation by 2iP is decreased in rpn12a-1 hypocotyls. Hypocotyl segments of 5-day-old seedlings were incubated for 2 weeks in the presence of 1 μM indole-3-acetic acid supplemented with a range of 2iP concentrations.

(H) The induction of greening by 2iP is decreased in rpn12a-1 roots. Root segments of 5-day-old wild-type and rpn12a-1 seedlings were incubated for 2 weeks in the presence of 1 μM indole-3-acetic acid supplemented with a range of 2iP concentrations.

In both (G) and (H), representative segments from separate 2iP treatments were aligned before photography.