Gene Details:

• MSU gene ID: LOC_Os03g57940
• RAPdb gene ID: Os03g0793500
• Gene Symbol: CKI EL1 Hd16
• Genome: MSU7 ,  IRGSP-1.0
• Species: Oryza sativa

Functional Descriptions:

• Rice homeobox transcription factor HOX1a positively regulates gibberellin responses by directly suppressing EL1.
• In addition, QTLs near Hd2, Hd16, and Ghd7, which are involved in inhibition of heading under long-day conditions, function in the same pathway that controls heading date.
• Map-based cloning revealed that the rice flowering-time quantitative trait locus (QTL) Heading date 16 (Hd16) encodes a casein kinase-I protein.
• By using near-isogenic lines with functional or deficient alleles of several rice flowering-time genes, we observed significant digenetic interactions between Hd16 and four other flowering-time genes (Ghd7, Hd1, DTH8 and Hd2).
• These results demonstrate that Hd16 acts as an inhibitor in the rice flowering pathway by enhancing the photoperiod response as a result of the phosphorylation of Ghd7.
• Hd16, a gene for casein kinase I, is involved in the control of rice flowering time by modulating the day-length response.
• In addition, HOX1a suppresses the transcription of early flowering1 (EL1), a negative regulator of GA signaling, and further electrophoretic mobility shift assay and chromatin immunoprecipitation analysis revealed that HOX1a directly bound to the promoter region of EL1 to suppress its expression and stimulate GA signaling.
• Rice early flowering1, a CKI, phosphorylates DELLA protein SLR1 to negatively regulate gibberellin signalling.
• To study the relevant regulatory mechanisms, we isolated a rice mutant earlier flowering1, EL1, which is deficient in a casein kinase I that has critical roles in both plants and animals.
• Overexpression of SLR1 in wild-type plants caused a severe dwarf phenotype, which was significantly suppressed by EL1 deficiency, indicating the negative effect of SLR1 on GA signalling requires the EL1 function.
• These results demonstrate that HOX1a functions as a positive regulator of GA signaling by suppressing EL1, providing informative hints on the study of GA signaling.
• EL1 had an enhanced GA response, consistent with the suppression of EL1 expression by exogenous GA(3).
• This study shows EL1 a novel and key regulator of the GA response and provided important clues on casein kinase I activities in GA signalling and plant development.
• To confirm the negative effect of the EL1 mutation on spikelet fertility, we examined a line carrying a T-DNA insertion EL1 mutant [hereafter ZH11(EL1)] and its parental cultivar ‘Zhonghua11 (ZH11)’.
• The EL1 mutation contributes to early flowering in japonica rice under long days but fails to limit GA signaling, thus negatively affecting spikelet fertility, which results in a loss of grain yield.
• Thus, EL1 is essential for photoperiod sensitivity in flowering as well as spikelet fertility in grain production.
• However, the elite japonica cultivar Koshihikari, which has a nonfunctional EL1 allele for early flowering in long days, produces fertile spikelets and normal grain yields, like other elite japonica cultivars.
• This indicates that as-yet-unknown regulator(s) that can overcome the male sterile phenotype of the EL1 mutation must have been introduced into Koshihikari.
• Here, we identified two casein kinase genes, Hd16 and Hd6, which modulate the expression of florigen genes within certain restricted ranges of photoperiod, thereby fine-tuning the critical day length.
• Tightly controlled expression of OsbHLH35 is critical for anther development in rice.
• Our data suggest that OsbHLH35 plays an essential role in anther development in rice and the fine control of its expression is crucial to ensure proper seed production.
• Rice transgenic plants expressing GUS reporter gene under the control of OsbHLH35 promoter (pOsbHLH35::GUS) showed that this TF specifically accumulates in anthers at the meiosis stage and in other spikelet tissues.
• Plants overexpressing OsbHLH35 presented small and curved anthers, leading to a reduction of 72 % on seed production.
• Yeast one-hybrid screening identified three members of the Growth-Regulating Factor (GRF) family, OsGRF3, OsGRF4, and OsGRF11, as transcriptional regulators of OsbHLH35.

Function-related keywords:

• gibberellin ,  heading-date ,  flower ,  transcription-factor ,  dwarf ,  ga ,  flowering-time ,  spikelet ,  grain ,  grain-yield ,  yield ,  fertility ,  sterile ,  GA ,  Kinase ,  development ,  anther ,  seed ,  meiosis ,  anther-development ,  transcriptional-regulator

Literature:

• Genetic interactions involved in the inhibition of heading by heading date QTL, Hd2 in rice under long-day conditions .  DOI:  10.1007/s00122-011-1654-0 ;  PMID:  21789706
• Rice early flowering1, a CKI, phosphorylates DELLA protein SLR1 to negatively regulate gibberellin signalling .  DOI:  10.1038/emboj.2010.75 ;  PMID:  20400938
• Rice homeobox transcription factor HOX1a positively regulates gibberellin responses by directly suppressing EL1 .  DOI:  10.1111/j.1744-7909.2011.01075.x ;  PMID:  21951842
• Hd16, a gene for casein kinase I, is involved in the control of rice flowering time by modulating the day-length response .  DOI:  10.1111/tpj.12268 ;  PMID:  23789941
• The Rice Floral Repressor Early flowering1 Affects Spikelet Fertility By Modulating Gibberellin Signaling .  DOI:  10.1186/s12284-015-0058-1 ;  PMID:  26202549
• Fine-tuning of the setting of critical day length by two casein kinases in rice photoperiodic flowering .  DOI:  10.1093/jxb/erx412 ;  PMID:  29237079
• Transcriptional and post-transcriptional regulation of heading date in rice .  DOI:  10.1111/nph.17158 ;  PMID:  33341945
• Tightly controlled expression of OsbHLH35 is critical for anther development in rice .  DOI:  10.1016/j.plantsci.2020.110716 ;  PMID:  33288022
• Magnaporthe oryzae systemic defense trigger 1 (MoSDT1)-mediated metabolites regulate defense response in Rice .  DOI:  10.1186/s12870-020-02821-6 ;  PMID:  33430779

Related News:

Gene Resources:

• NCBI ID:
• UniProt accessions:

Sequences: