Discipline: Biological Sciences
Subcategory: Cell and Molecular Biology
Nhu H. Nguyen - University of Washington
Co-Author(s): Akane Kubota, University of Washington, Seattle, WA; Takato Imaizumi, University of Washington, Seattle, WA.
Scientists agree that recent climate change results in plant growth and therefore agricultural efficiency. To ensure the steadiness of harvestable crop yields, it is critical to understand how plants adjust flowering timing to a changing climate. Photoperiod (the length of a day) and daily temperature oscillation regulate the flowering timing in the model plant Arabidopsis thaliana through the transcriptional regulation of FLOWERING LOCUS T (FT) gene, which encodes florigen and promotes flowering. It has been shown that the expression of FT peaks in the evening under long-day (LD) lab conditions (16 hours of light, 8 hours of darkness, constant 22°C, 2:1 Red:Far-red ratio). To examine if this mechanism still explains what happens in nature, the Imaizumi Lab analyzed FT expression under outside long-day conditions over the summer solstice in Seattle, Washington (16 hours of light, 8 hours of darkness, highest average temperature 21°C, 1:1 Red:Far-red ratio). Surprisingly, they found that FT also peaks in the morning. In addition, flowering in the outside condition was accelerated compared to the in-lab normal LD conditions. Given that FT is a major flowering regulator in plants, the lab hypothesized that the additional expression of FT in the morning may explain why plants outside flowered earlier than the in-lab normal LD conditions, and aimed to understand the mechanism of FT regulation in the morning. This double-peak of FT was then successfully re-created by changing the temperature and light settings of conventional LD conditions commonly used in different laboratories. The lab also found that CONSTANS (CO) and EARLY FLOWERING 3 (ELF3) contribute to generating the double peak of FT. Therefore, this project was designed to understand how ELF3 and CO take part in controlling flowering in natural LD conditions. First, we established co101 elf3-1 double mutant and analyzed the flowering timing in both conventional LD and re-created natural LD (16 hours of light, 8 hours of darkness, oscillated temperature from 16 to 22°C, 1:1 Red:Far-red ratio) conditions. In both conditions, co101 elf3-1 flowered much later than elf3-1, but slightly earlier than co101. Interestingly, different growth conditions caused a change in the flowering timing in all lines but elf3-1. These results suggest that ELF3 plays an integral role in distinguishing the growth conditions to adjust the flowering timing, and that ELF3 affects flowering mainly, but not solely in a CO-dependent manner. The expression of flowering genes including FT is now being analyzed. In addition, we are going to generate an ft elf3 double mutant to determine whether ELF3 regulates the expression of ft independently from the CO-FT pathway or directly through FT. Taken together, the results from our upcoming project will progress to a better understanding regarding the molecular mechanism of seasonal flowering in nature.Nhu Nguyen ERN 2018 Abstract.docx
Funder Acknowledgement(s): University of Washington GenOM Project (NIH 5R25HG007153-05)
Faculty Advisor: Akane Kubota, Ph.D, firstname.lastname@example.org
Role: When I first joined the Imaizumi Lab, I was given the co elf3 double mutant plants which had already grown and been taken care of. Under my mentor's supervision, I first performed genotyping to confirm all co elf3 double mutants to be indeed homozygous by extracting DNA, operating PCR, running agarose gels and applying restriction enzyme. At the same time, I also analyzed the flowering phenotype by counting the number of leaves when each plant had bolted was utilized as a proxy for estimating the flowering timing. We are currently analyzing the expression of FT in these mutant lines.