A Photoperiod-Insensitive Barley Line Contains a Light-Labile Phytochrome B1

Hanumappa, Mamatha; Pratt, Lee H.; Cordonnier‐Pratt, Marie‐Michèle; Deitzer, Gerald F.

doi:10.1104/pp.119.3.1033

Cited by 47 publications

(27 citation statements)

References 34 publications

(57 reference statements)

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“…Timing may be less important for the phyB responses because it mainly mediates the shade avoidance responses. However, it should be mentioned here that phyB is also involved in photoperiodic flowering in other species (Hanumappa et al, 1999;Weller et al, 2001). phyB perceives the reduction in the ratio of red to far-red light.…”

Section: Flowering Regulation By Phyb and Cry2mentioning

confidence: 91%

CRYPTOCHROME2 in Vascular Bundles Regulates Flowering in Arabidopsis

et al. 2007

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Plants make full use of light signals to determine the timing of flowering. In Arabidopsis thaliana, a blue/UV-A photoreceptor, CRYPTOCHROME 2 (cry2), and a red/far-red photoreceptor, PHYTOCHROME B (phyB), are two major photoreceptors that control flowering. The light stimuli for the regulation of flowering are perceived by leaves. We have recently shown that phyB expression in mesophyll but not in vascular bundles suppresses the expression of a key flowering regulator, FLOWERING LOCUS T (FT), in vascular bundles. In this study, we asked where in the leaf cry2 perceives light stimuli to regulate flowering. To answer this question, we established transgenic Arabidopsis lines in which the cry2-green fluorescent protein (GFP) fusion was expressed under the control of organ/tissue-specific promoters in a cry2-deficient mutant background. Analysis of these lines revealed that expression of cry2-GFP in vascular bundles, but not in epidermis or mesophyll, rescued the late flowering phenotype. We further confirmed that cry2-GFP expressed in vascular bundles increased FT expression only in vascular bundles. Hence, in striking contrast with phyB, cry2 most likely regulates FT expression in a cell-autonomous manner.

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Section: Flowering Regulation By Phyb and Cry2mentioning

confidence: 91%

CRYPTOCHROME2 in Vascular Bundles Regulates Flowering in Arabidopsis

et al. 2007

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“…The light-dependent induction of SbPRR37 expression and the clock-mediated eveningphase peak of expression enable SbPRR37 to regulate flowering time in response to photoperiod; PRR37 mRNA levels in the evening phase decrease as day length is reduced. The photoreceptor(s) that mediate light-induced SbPRR37 expression are currently under investigation; however, phytochrome B is likely involved because recessive alleles of this gene cause early flowering in LD in sorghum (ma 3 , ma 3 R ) (33), barley (34), and rice (35). SbPRR37 is proposed to repress FT, SbZCN8, and SbZCN12 and flowering in LD in part by inhibiting expression of Ehd1, an activator of FT and flowering in rice (12); by increasing expression of CO, a repressor of flowering in rice in LD (26); and possibly by other mechanisms that modulate SbFT and SbZCN8 expression (Fig.…”

Section: Photoperiod and The Circadian Clock Modulate Sbprr37 And Floralmentioning

confidence: 99%

Coincident light and clock regulation of pseudoresponse regulator protein 37 ( PRR37 ) controls photoperiodic flowering in sorghum

Murphy

Klein

Morishige

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

319

362

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Optimal flowering time is critical to the success of modern agriculture. Sorghum is a short-day tropical species that exhibits substantial photoperiod sensitivity and delayed flowering in long days. Genotypes with reduced photoperiod sensitivity enabled sorghum's utilization as a grain crop in temperate zones worldwide. In the present study, Ma 1 , the major repressor of sorghum flowering in long days, was identified as the pseudoresponse regulator protein 37 (PRR37) through positional cloning and analysis of SbPRR37 alleles that modulate flowering time in grain and energy sorghum. Several allelic variants of SbPRR37 were identified in early flowering grain sorghum germplasm that contain unique loss-of-function mutations. We show that in long days SbPRR37 activates expression of the floral inhibitor CONSTANS and represses expression of the floral activators Early Heading Date 1, FLOWERING LOCUS T, Zea mays CENTRORADIALIS 8, and floral induction. Expression of SbPRR37 is light dependent and regulated by the circadian clock, with peaks of RNA abundance in the morning and evening in long days. In short days, the evening-phase expression of SbPRR37 does not occur due to darkness, allowing sorghum to flower in this photoperiod. This study provides insight into an external coincidence mechanism of photoperiodic regulation of flowering time mediated by PRR37 in the short-day grass sorghum and identifies important alleles of SbPRR37 that are critical for the utilization of this tropical grass in temperate zone grain and bioenergy production.is a C4 grass native to Africa that provides an indispensable food source for over 300 million people inhabiting food-insecure regions worldwide (1). Although primarily grown for its grain and forage, highbiomass sorghum is also an excellent drought-tolerant energy crop for sustainable production of lignocellulosic-based biofuels (2). Forage and energy sorghums are selected for delayed flowering to increase biomass yield through longer duration of vegetative growth, whereas grain sorghums are selected for early flowering to ensure sufficient time for grain maturation and to avoid drought and frost. Optimal production of each of these sorghum crops requires the precise regulation of flowering time, which varies depending on planting location and climate. Differences in photoperiod sensitivity confer a wide range of flowering times on diverse accessions of the sorghum germplasm collection (3). Due to its critical importance to crop yield and hybrid seed production, photoperiodic regulation of flowering has been an important trait characterized by sorghum improvement programs dating back to the early 1900s (4).In Arabidopsis, flowering is induced in long days (LD) that expose plants to light in the evening during a phase of circadian clock oscillation required for induction of floral genes, consistent with the external coincidence model (5-7). Rhythmic expression of the core circadian clock components CIRCADIAN CLOCK ASSOCIATED 1 (CCA1)/LATE ELONGATED HYPOCOTYL (LHY) and TIMING OF CAB 1...

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“…Although phytochromes play a supporting role in regulating floral transitions such as entrainment of circadian clocks and stability control of a key regulator, CONSTANS (CO), in Arabidopsis (Franklin and Quail, 2010), blue-light signals seem to be even more important in the LD response in this species. Nevertheless, it has been long thought that phytochromes are essential for daylength measurement in many other plants, based on numerous physiological analyses (Hanumappa et al, 1999;Izawa et al, 2000). It is also known that phytochromes control the photoperiodic control of flowering in rice (Oryza sativa), a model SD plant, because flowering time in photoperiod sensitivity5 (se5), a phytochrome chromophore mutant of phytochromes in rice, exhibits extremely early flowering and is completely insensitive to daylength (often, slightly earlier under LD conditions than SD; Izawa et al, 2000).…”

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confidence: 99%