Isolation of novel gain- and loss-of-function alleles of the circadian clock gene LATE ELONGATED HYPOCOTYL (LHY) in Arabidopsis

Oda, Atsushi; Reeves, Paul H.; Tajima, Takeomi; Nakagawa, Mayu; Kamada, Hiroshi; Coupland, George; Mizoguchi, Tsuyoshi

doi:10.5511/plantbiotechnology.24.457

Cited by 2 publications

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“…In general, a gene is considered a core circadian clock component when its loss or gain of function results in a change in period under continuous light and temperature, or free-run conditions. For instance, the loss of either LHY or CCA1 results in a short free-running period (FRP) of 21 h, while the double mutant cca1/lhy results in an very short FRP of 18 h suggesting that these paralogs are redundant in core circadian clock function ( Figure 1A ; Supplemental Note S1 ; Green and Tobin, 1999 ; Alabadı’ et al, 2002 ; Mizoguchi et al, 2002 ; Oda et al, 2007 ; Lu et al, 2009 ; Salomé et al, 2010 ). Of the RVE family, only the single loss of RVE8/LCL5 results in a longer FRP ( Farinas and Mas, 2011 ; Rawat et al, 2011 ), while the doubles ( rve4/8 , 27 h; rve6/8 , 26 h) triple ( rve4/6/8 , 28 h), or quadruple ( rve3/4/5/6/8 , 28 h) results in a progressively longer FRP consistent with the other RVEs also playing a role in the core circadian clock ( Hsu et al, 2013 ; Gray et al, 2017 ).…”

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Core circadian clock and light signaling genes brought into genetic linkage across the green lineage

Michael

2022

Plant Physiology

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The circadian clock is conserved at both the level of transcriptional networks as well as core genes in plants, ensuring that biological processes are phased to the correct time of day. In the model plant Arabidopsis (Arabidopsis thaliana), the core circadian SHAQKYF-type-MYB (sMYB) genes CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) and REVEILLE (RVE4) show genetic linkage with PSEUDO-RESPONSE REGULATOR 9 (PRR9) and PRR7, respectively. Leveraging chromosome-resolved plant genomes and syntenic ortholog analysis enabled tracing this genetic linkage back to Amborella trichopoda, a sister lineage to the angiosperm, and identifying an additional evolutionarily conserved genetic linkage in light signaling genes. The LHY/CCA1–PRR5/9, RVE4/8–PRR3/7, and PIF3–PHYA genetic linkages emerged in the bryophyte lineage and progressively moved within several genes of each other across an array of angiosperm families representing distinct whole-genome duplication and fractionation events. Soybean (Glycine max) maintained all but two genetic linkages, and expression analysis revealed the PIF3–PHYA linkage overlapping with the E4 maturity group locus was the only pair to robustly cycle with an evening phase, in contrast to the sMYB–PRR morning and midday phase. While most monocots maintain the genetic linkages, they have been lost in the economically important grasses (Poaceae), such as maize (Zea mays), where the genes have been fractionated to separate chromosomes and presence/absence variation results in the segregation of PRR7 paralogs across heterotic groups. The environmental robustness model is put forward, suggesting that evolutionarily conserved genetic linkages ensure superior microhabitat pollinator synchrony, while wide-hybrids or unlinking the genes, as seen in the grasses, result in heterosis, adaptation, and colonization of new ecological niches.

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Section: Introductionmentioning

confidence: 99%

Core circadian clock and light signaling genes brought into genetic linkage across the green lineage

Michael

2022

Plant Physiology

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“…In Arabidopsis, LATE ELONGATED HYPOCOTYL (LHY) and CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) encode myb proteins essential for clock function (Schaffer et al 1998;Wang and Tobin 1998). FLOWERING LOCUS T (FT) plays a pivotal role in the photoperiodic flowering affected by the circadian clock (Fujiwara et al 2005a(Fujiwara et al , 2005b(Fujiwara et al , 2005cMizoguchi et al 2005;Oda et al 2007) and is an important component of the elusive "florigen" signal (Abe et al 2005;Huang et al 2005;Wigge et al 2005). GIGANTEA (GI) and CONSTANS (CO) are mediators between the circadian clock and the FT in photoperiodic control of flowering in Arabidopsis under conditions of light/dark cycling (Calvino et al 2005;Mizoguchi et al 2005;Súarez-López et al 2001;Yanovsky and Kay 2002).…”

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Possible involvement of FLC in natural variation of activity to enhance the late flowering phenotype of the clock mutant lhy cca1 under continuous light

Tajima

Yoshida

Oda

et al. 2010

Plant Biotechnology

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LHY and CCA1 play key roles in circadian clock functions and photoperiodic flowering in Arabidopsis. Double loss of function of LHY and CCA1 genes (lhy cca1) accelerated flowering under long days or short days, but the lhy cca1 delayed flowering time under constant-light (LL) conditions. FCA encodes an RNA binding protein that plays key roles in the autonomous pathway. Loss of function of FCA increases mRNA level of a major floral repressor gene, FLC. A mutation in FLC gene partially suppressed the late flowering phenotype of the lhy cca1 in LL. Based on this result, we have proposed that FLC may be involved in this process. Increased level of FLC mRNA in fca is responsible for the delay of flowering and the late flowering phenotype of the fca is suppressed by vernalization. In this paper, we isolated an enhancer of the lateflowering phenotype of the lhy cca1 in LL based on natural variation of two Arabidopsis accessions, Columbia and Landsberg erecata. The enhancer was named ELLCL and mapped near the FLC. This result suggested that the gene responsive to ELLCL might be FLC and was consistent with our previous results. The late-flowering phenotype of lhy cca1 was insensitive to vernalization. By contrast, flowering time of the fca was accelerated by vernalization as reported. These results suggested that posttranslational, but not the transcriptional, regulation of FLC might be involved in this process. Key words: CCA1, circadian rhythms, FLC, LHY, natural variation.Plant Biotechnology 27, 455-461 (2010) Short CommunicationAbbreviations: CCA1, CIRCADIAN CLOCK ASSOCIATED 1; FLC, FLOWERING LOCUS C; LHY, LATE ELONGATED HYPOCOTYL; LD, long-days, LL, continuous light, SD, short-days; SVP, SHORT VEGETATIVE PHASE. This article can be found at http://www.jspcmb.jp/ the late-flowering phenotype of lhy cca1 under LL by both ethyl methanesulfonate (EMS) mutagenesis and genetic analysis. Based on our results, we proposed novel roles of the oscillator components LHY and CCA1 in the control of flowering time through the ELF3-SVP/FLC pathway in Arabidopsis (Mizoguchi and Yoshida 2009).Some mutations in key clock genes resulted in severe defects in clock function and differences between phenotypes of plants with these mutations under conditions of light/dark cycling compared with under LL. These circadian clock mutants include lhy cca1 (Fujiwara et al. 2008;Yoshida et al. 2009), elf3 cry2 (Natsui et al. 2010, and prr9 prr7 prr5 . Petiole length of prr9 prr7 prr5 was longer than that of wild-type plants under LD, but shorter under LL . Both lhy cca1 and elf3 cry2 produced fewer and more leaves than wild-type plants under SD and LL, respectively. Nevertheless, isolation of enhancers and suppressors of these mutants would be important to understand the precise molecular mechanism of inversion in the photoperiodic response type. Therefore, we performed mutagenesis of lhy cca1 seeds with EMS and screening of putative enhancers and suppressors of the clock mutant. Use of natural populations has several advantages for ...

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Isolation of novel gain- and loss-of-function alleles of the circadian clock gene LATE ELONGATED HYPOCOTYL (LHY) in Arabidopsis

Cited by 2 publications

References 36 publications

Core circadian clock and light signaling genes brought into genetic linkage across the green lineage

Core circadian clock and light signaling genes brought into genetic linkage across the green lineage

Possible involvement of FLC in natural variation of activity to enhance the late flowering phenotype of the clock mutant lhy cca1 under continuous light

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