(A) Light-grown corn (B) Dark-grown corn (c) Light-grown bean (D) Dark-grown bean Figure g-1
Figure 9-1
Dark Red Far-red Figure 9-2 数 FIGURE 17.2 Lettuce seed germination is a typical photore- versible response controlled by phytochrome. Red light promotes lettuce seed germination, but this effect is reversed by far-red light. Imbibed(water-moistened)seeds were given alternating treatments of red followed by far red light. The effect of the light treatment depended on the Red Far-red Red Red Far-red Red Far-red last treatment given. (Photos O M B. Wilkins
Figure 9-2
First node 12 长10 FIGURE 17.6 Phytochrome is 20 most heavily concentrated in Root the regions where dramatic developmental changes are 20 curring: the apical meristem of the epicotyl and root Shown 10 here is the distribution of ph chrome in an etiolated pea seedling, as measured spec Concentration of phytochrome Kendrick and Frankland 1983) Figure 9-3
Figure 9-3
Chromophore: phytochromobilin P His ser B N 1 ys Leu Thioether Cis isomer GIn linkage Red light converts cis to trans Pro R R 15 se 1 Trans isomer His Leu GIn igure 9-5 FIGURE 17. 4 Structure of the Pr and pfr forms of the chro mophore (phytochromobilin) and the peptide region bound to the chromophore through a thioether linkage. The chro- mophore undergoes a cis-trans isomerization at carbon 15 in response to red and far-red light. (After Andel et al. 1997.)
Figure 9-5
Chromophore-binding domains A A B IIB FIGURE 17.5 Structure of the phytochrome dimer. The monomers are labeled I and Il. Each monomer consists of a chromophore-binding domain(A)and a smaller nonchro mophore domain(b). The molecule as a whole has an elli soidal rather than globular shape. (After Tokutomi et al 1989) Figure g-5-1
Figure 9-5-1