Arabidopsis plants

Wang Qin/UCLA molecular, cell and developmental biology

The left side panels show young Arabidopsis seedlings grown in blue light. The left two seedlings are normal, with show short stems and large leaves because blue light inhibits stem growth, but stimulates leaf expansion. In the two seedlings on the right side cryptochromes have been removed). These seedlings show long stems and small leaves because they lack the cryptochrome photoreceptor, and therefore lack blue light inhibition of stem growth and lack blue light stimulation of leaf expansion.

The right side panels shows adult Arabidopsis plants, grown in 16 hours of blue light and eight hours of dark to mimic summer days.  The normal plants have flowers, but the ones without cryptochromes failed to flower. This is because plants that have no cryptochrome photoreceptors cannot perceive the day-length signals.

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