Temperature-dependent internode elongation in vegetative plants of Arabidopsis thaliana lacking phytochrome B and cryptochrome 1 |
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Authors: | María Agustina Mazzella Daniel Bertero Jorge José Casal |
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Institution: | (1) IFEVA, Departamento de Ecología, Facultad de Agronomía, Universidad de Buenos Aires, Av. San Martín 4453, 1417 Buenos Aires, Argentina, AR |
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Abstract: | 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 flower buds are present in the reproductive apex. Under natural radiation, continuous light from fluorescent
lamps, or short photoperiods of light from fluorescent lamps, plants of the phyB cry1 double mutant (lacking both phytochrome B and cryptochrome 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 effects. The
failure to form normal rosettes was conditional because internode elongation was arrested at low temperatures in all the mutant
combinations. In contrast, the temperature dependence of phytochrome B and cryptochrome 1 effects on hypocotyl growth was
weak. The elongation of the internodes in phyB cry1 was not accompanied by early flowering as showed by the lack of effects on the final 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.
Received: 2 June 1999 / Accepted: 13 August 1999 |
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Keywords: | : Arabidopsis– Cryptochrome – Phytochrome – Stem growth – Vegetative development |
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