Temperature-dependent internode elongation in vegetative plants of Arabidopsis thaliana lacking phytochrome B and cryptochrome 1

MAZZELLA MA, BERTERO D, CASAL JJ

PLANTA

SPRINGER

Lugar: Berlin; Año: 2000 vol. 210 p. 497 - 501

0032-0935

Vegetative plants of Arabidopsis thaliana (L.) Heynh. form a compact rosette of leaves in which internode growth is virtually arrested. Rapid extension of the internodes occurs after ¯ower buds are present in the reproductive apex. Under natural radiation, contin- uous light from ¯uorescent lamps, or short photoperiods of light from ¯uorescent lamps, plants of the phyB cry1 double mutant (lacking both phytochrome B and crypto- chrome 1) did not form normal rosettes because all the internodes showed some degree of elongation. Internode elongation was weak in the phyB single mutant and absent in the cry1 mutant, indicating redundancy between phytochrome B and cryptochrome 1. The absence of phytochrome A caused no e€ects. The failure to form normal rosettes was conditional because internode elon- gation was arrested at low temperatures in all the mutant combinations. In contrast, the temperature dependence of phytochrome B and cryptochrome 1 e€ects on hypocotyl growth was weak. The elongation of the internodes in phyB cry1 was not accompanied by early ¯owering as showed by the lack of e€ects on the ®nal number of leaves. Apex dissection indicated that in phyB cry1 double mutants internode elongation anticipated the transition from the vegetative to the reproductive stage. Thus, stem growth in Arabidopsis thaliana is not fully dependent on the program of reproductive development.