Findings announced: The daily localization and dispersion of proteins that control fluorescence and regulate seasonal flowering times

The Center for Systems Biology of Plant Senescence and Life History, directed by Hong Gil Nam at the Institute for Basic Science (IBS) has reported its findings on the localization and dispersion of plant nuclear proteins that affect seasonal flowering times.

Led by Dr. Yu-mi Kim at the Center for Systems Biology of Plant Senescence and Life History, the study was published in Cell Reports, the sister magazine of Cell, the globally renowned journal on March 21. The findings suggest possible solutions to global food shortages, by producing earlier harvests through control over plant-flowering times.

Fluorescence is generally controlled by the interaction between environmental factors (such as seasonal changes) and a plant's genetic make-up.

Among the various factors, seasonal changes, longer days, and increased exposure to light are known to trigger the biological clock of the plant. In particular, a protein called GIGANTEA was identified as responsible for controlling the activity of the plant's biological clock, which stimulated flowering. The original discovery's findings were published (by Nam et al) in Science in 1999.

Using the earlier findings as a starting point, the team discovered a number of genes associated with photoperiodic flowering and the biological clock. After thorough experimentation, they demonstrated how the flowering time can be manipulated by controlling the activity of genes and proteins.

Nam et al discovered that GIGANTEA was the flowering-inducing protein, and that it has two distinctive nuclear localization profiles: One is evenly dispersed in the nucleus; the other is localized in the nuclear body containing various proteins. The plant used in tests was Arabidopsis (mouse-ear cress), a long-day species.

GIGANTEA was observed in dispersed localization profile during daytime, and in localized form (in the nuclear body) at night.

The team also demonstrated that the localization of GIGANTEA in the nuclear body is induced by directly binding it with the ELF4 protein (expressed mainly during the night).

These findings give crucial insight into methods of controlling the flowering times of long-day plants that bloom early during spring as the days grow longer, but bloom late during the autumn, as the days get shorter.

Other proteins have been discovered that affect a plant's biological clock, and which form a nuclear body. Nonetheless, this is the first demonstration of controlled flowering times by means of protein localization in the nuclear body, or by means of dispersion throughout the nucleus.

"Our findings have revealed a novel mechanism for controlling flowering times via the nuclear-localization patterns of the protein responsible for flowering. Therefore, the mechanism is distinct from previously discovered ones. As such, it offers valuable clues about methods we can adopt to combat the food shortage problem, by conducting research on plant development and life cycles," said Dr. Nam.