Phytochrome B regulates Heading date 1 (Hd1)-mediated expression of rice florigen Hd3a and critical day length in rice

Ishikawa, Ryo; Aoki, M.; Kurotani, Ken-ichi; Yokoi, Shuji; Shinomura, Tomoko; Takano, Makoto; Shimamoto, Ko

doi:10.1007/s00438-011-0621-4

Cited by 135 publications

(112 citation statements)

References 44 publications

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“…Overexpression of barley CO1 in barley results in accelerated flowering time under LD (51), suggesting that CO1 promotes flowering. However, CO overexpression results should be interpreted with caution because overexpression of HD1 in rice results in delayed flowering time under SD even though this gene naturally works as a flowering promoter under SD (52). These conflicting results suggest that a precise spatial and/or temporal expression of CO homologs and/or a precise balance of their relative protein levels with other partners are required for their characteristic functions in different species.…”

Section: Phyc Is Involved In the Transcriptional Regulation Of Bothmentioning

confidence: 99%

PHYTOCHROME C plays a major role in the acceleration of wheat flowering under long-day photoperiod

Chen¹,

et al. 2014

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

179

228

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Phytochromes are dimeric proteins that function as red and far-red light sensors influencing nearly every phase of the plant life cycle. Of the three major phytochrome families found in flowering plants, PHYTOCHROME C (PHYC) is the least understood. In Arabidopsis and rice, PHYC is unstable and functionally inactive unless it heterodimerizes with another phytochrome. However, when expressed in an Arabidopsis phy-null mutant, wheat PHYC forms signaling active homodimers that translocate into the nucleus in red light to mediate photomorphogenic responses. Tetraploid wheat plants homozygous for loss-of-function mutations in all PHYC copies (phyC AB ) flower on average 108 d later than wild-type plants under long days but only 19 d later under short days, indicating a strong interaction between PHYC and photoperiod. This interaction is further supported by the drastic down-regulation in the phyC AB mutant of the central photoperiod gene PHOTOPERIOD 1 (PPD1) and its downstream target FLOWERING LOCUS T1, which are required for the promotion of flowering under long days. These results implicate light-dependent, PHYC-mediated activation of PPD1 expression in the acceleration of wheat flowering under inductive long days. Plants homozygous for the phyC AB mutations also show altered profiles of circadian clock and clock-output genes, which may also contribute to the observed differences in heading time. Our results highlight important differences in the photoperiod pathways of the temperate grasses with those of well-studied model plant species.

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Section: Phyc Is Involved In the Transcriptional Regulation Of Bothmentioning

confidence: 99%

PHYTOCHROME C plays a major role in the acceleration of wheat flowering under long-day photoperiod

Chen¹,

et al. 2014

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

179

228

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“…Heading date 1 (Hd1, counterpart of Arabidopsis [Arabidopsis thaliana] CONSTANS, CO), Days to heading 2 (DTH2, encoding another CO-like protein), and Early heading date 1 (Ehd1) regulate expression of these two "florigen" genes. Hd1 acts as a transcription activator for Hd3a in SDs but as a repressor in the presence of functional O. sativa Phytochrome B in LDs (Hayama et al, 2003;Ishikawa et al, 2011). DTH2 acts in LDs to suppress flowering .…”

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confidence: 99%

A Drought-Inducible Transcription Factor Delays Reproductive Timing in Rice

Zhang

Zhao

et al. 2016

Plant Physiol.

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The molecular mechanisms underlying photoperiod or temperature control of flowering time have been recently elucidated, but how plants regulate flowering time in response to other external factors, such as water availability, remains poorly understood. Using a large-scale Hybrid Transcription Factor approach, we identified a bZIP transcriptional factor, O. sativa ABA responsive element binding factor 1 (OsABF1), which acts as a suppressor of floral transition in a photoperiod-independent manner. Simultaneous knockdown of both OsABF1 and its closest homologous gene, OsbZIP40, in rice (Oryza sativa) by RNA interference results in a significantly earlier flowering phenotype. Molecular and genetic analyses demonstrate that a drought regime enhances expression of the OsABF1 gene, which indirectly suppresses expression of the Early heading date 1 (Ehd1) gene that encodes a key activator of rice flowering. Furthermore, we identified a drought-inducible gene named OsWRKY104 that is under the direct regulation of OsABF1. Overexpression of OsWRKY104 can suppress Ehd1 expression and confers a later flowering phenotype in rice. Together, these findings reveal a novel pathway by which rice modulates heading date in response to the change of ambient water availability.Flowering time (or heading date) and drought resistance are two major yield traits in crops, especially rice (Oryza sativa). As global climatic change looms, drought has become the biggest abiotic stress to limit crop yields. Breeders have capitalized on naturally occurring genetic variations to improve or maintain crop yield in times or areas of drought by different strategies (Eisenstein, 2013). Manipulation of floral transition has been a promising way to maximize crop yield during dry periods. This strategy has been successful due to extensive identification of genetic loci and elucidation of molecular mechanisms that control flowering time under diverse or unpredictable environments.Heading date in rice is influenced by many environmental cues such as day length (photoperiod), temperature, nutrition, and water availability. Molecular mechanisms that underlie photoperiod regulation of flowering time have already been characterized, probably because day length is more predictable than other environmental factors during seasonal changes. Rice is a facultative short-day plant that flowers earlier in short days (SDs) than in long days (LDs). Heading date 3a (Hd3a) and RICE FLOWERING LOCUS T1 (RFT1) are two paralogous genes in rice encoding "florigen" molecules expressed in the phloem of leaves and transported to the shoot apical meristem to promote flowering (Tamaki et al., 2007;

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“…Upstream of these florigen genes, Heading date 1 (Hd1) and Early heading date 1 (Ehd1) function as two major floral signal integrators that receive multiple signals from other genes, including OsGIGANTEA (OsGI), Rice Indeterminate 1 (RID1; also known as OsID1/Ehd2), Early heading date 3 (Ehd3), OsMADS50, OsMADS51, Ghd7 (for Grain number, plant height, and heading date 7), DTH8 (for days to heading on chromosome 8), PHYB (PHYTOCHROME B), and SE5 (PHOTO-PERIOD SENSITIVITY 5), to regulate the expression of florigen genes (2,(25)(26)(27)(28)(29)(30)(31). Analyses of these flowering-time genes have given several hints about local adaptation in rice.…”

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confidence: 99%

Association of functional nucleotide polymorphisms at DTH2 with the northward expansion of rice cultivation in Asia

Zheng

et al. 2013

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

173

149

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Flowering time (i.e., heading date in crops) is an important ecological trait that determines growing seasons and regional adaptability of plants to specific natural environments. Rice (Oryza sativa L.) is a short-day plant that originated in the tropics. Increasing evidence suggests that the northward expansion of cultivated rice was accompanied by human selection of the heading date under noninductive long-day (LD) conditions. We report here the molecular cloning and characterization of DTH2 (for Days to heading on chromosome 2), a minor-effect quantitative trait locus that promotes heading under LD conditions. We show that DTH2 encodes a CONSTANS-like protein that promotes heading by inducing the florigen genes Heading date 3a and RICE FLOWERING LOCUS T 1, and it acts independently of the known floral integrators Heading date 1 and Early heading date 1. Moreover, association analysis and transgenic experiments identified two functional nucleotide polymorphisms in DTH2 that correlated with early heading and increased reproductive fitness under natural LD conditions in northern Asia. Our combined population genetics and network analyses suggest that DTH2 likely represents a target of human selection for adaptation to LD conditions during rice domestication and/or improvement, demonstrating an important role of minor-effect quantitative trait loci in crop adaptation and breeding.

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Phytochrome B regulates Heading date 1 (Hd1)-mediated expression of rice florigen Hd3a and critical day length in rice

Cited by 135 publications

References 44 publications

PHYTOCHROME C plays a major role in the acceleration of wheat flowering under long-day photoperiod

PHYTOCHROME C plays a major role in the acceleration of wheat flowering under long-day photoperiod

A Drought-Inducible Transcription Factor Delays Reproductive Timing in Rice

Association of functional nucleotide polymorphisms at DTH2 with the northward expansion of rice cultivation in Asia

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