Cryptochrome 1 Contributes to Blue-Light Sensing in Pea

Abstract

Cryptochromes are widespread in higher plants but their physiological roles as blue-light photoreceptors have been examined in relatively few species. Screening in a phyA null mutant background has identified several blue-light response mutants in pea (Pisum sativum), including one that carries a substitution of a highly conserved glycine residue in the N-terminal photolyasehomologous domain of the pea CRY1 gene. Analyses of cry1, phyA, and phyB mutants show that all three photoreceptors contribute to seedling photomorphogenesis under high-irradiance blue light, whereas phyA is the main photoreceptor active under low irradiances. Triple phyA phyB cry1 mutants grown under high-irradiance blue light are indistinguishable from darkgrown wild-type plants in length and leaf expansion but show a small residual response to higher-irradiance white light. Monogenic cry1 mutants have little discernable phenotype at the seedling stage, but later in development are more elongated than wild-type plants. In addition, the loss of cry1 moderates the short-internode phenotype of older phyA mutants, suggesting an antagonism between phyA and cry1 under some conditions. Pea cry1 has a small inhibitory effect on flowering under long and short days. However, the phyA cry1 double mutant retains a clear promotion of flowering in response to blue-light photoperiod extensions, indicating a role for one or more additional blue-light photoreceptors in the control of flowering in pea.

Light Regulation of Gibberellin Biosynthesis in Pea Is Mediated through the COP1/HY5 Pathway

“…Because the phyA phyB double mutant is insensitive to R (Weller et al, 2001), this shows that long1 affects both phyA and phyB signaling under R. It also shows that phytochrome signaling under R is not completely dependent on LONG1 because both the phyA long1 and phyB long1 double mutants are more responsive to R than the phyA phyB double mutant. Under B, the phyA long1 double mutant was less responsive than any of the three photoreceptor double mutants ( Figure 2B), and as the phyA phyB cry1 triple mutant is essentially insensitive to B (Platten et al, 2005), this implies that long1 affects signaling from all three photoreceptors in blue light.…”

“…In pea seedlings, phyA and phyB both contribute to deetiolation under R and act together with cry1 under B (Platten et al, 2005). To examine which specific photoreceptor signals were impaired by long1, we generated long1 phyA and long1 phyB double mutants.…”

“…The long1-1 point mutation was converted into a derived CAPS marker, introducing a diagnostic NcoI site. Molecular markers for detection of the phyA-1, phyB-5, la-1, and cry-s mutations have been described previously (Platten et al, 2005;Weston et al, 2008). Details of all primers are provided in Supplemental Table 1 online.…”

Association of the circadian rhythmic expression of GmCRY1a with a latitudinal cline in photoperiodic flowering of soybean

“…In Arabidopsis, CRY1 mediates mainly blue light control of deetiolation, whereas CRY2 regulates primarily photoperiodic flowering, defined here as the reaction to change flowering time in response to altered photoperiods (4,6,7). In addition to Arabidopsis, cryptochromes have also been studied in other plants, including algae (8), moss (9), fern (10), tomato (11,12), rapeseed (13), pea (14), and rice (15,16). Results of these studies indicate that cryptochromes in angiosperms generally regulate developmental aspects in ways that are similar to Arabidopsis.…”

Photoreceptor Biotechnology

“…Mutations in the cryptochrome genes also cause reduced sensitivity to photoperiod, but have the converse effect (causing plants to flower later under inductive conditions), in Arabidopsis , El-Din El-Assal et al, 2003. In contrast, cryptochrome mutants of pea are early flowering (Platten et al, 2005). In addition to the complexity added by the different photoperiodic responses of different species, altered photoreceptor levels affect many other aspects of phenotype and cause pleiotropic effects.…”