Scientists Find the Switch to Regulate Flowering

Posted by Ilsa Miller on January 29th, 2021

The natural world is amazing. Different plants have different flowering times. What magical power is controlling the flowering time? Scientists have been searching for this mystery.

The Li Peijin research group of the National and Local Joint Engineering Laboratory of Plant Resistance Breeding and Disaster Reduction, College of Life Sciences, Anhui Agricultural University, China, has revealed a new regulation mechanism of the natural variation of Arabidopsis blooming through research. This research result was recently published in Nature Communications.

Flowering time is a key agronomic trait, which has an important influence on plant yield and quality. Generally speaking, each plant has the best flowering period, during which the flowering can achieve stable and high yield. However, if the flowering period advances or lags behind, it will have an adverse effect on yield.

Li Peijin gave an example: Maize is extremely sensitive to high temperature during the flowering period. If it blooms in hot weather in July, it will lead to uncoordinated male and female flowering periods and pollination failure. In severe cases, the grain will not be harvested, which will cause major losses to agricultural production. Therefore, analyzing the flowering mechanism of plants has important practical significance for plant molecular assisted breeding and increasing crop yields.

Plant evolution is a long process. The same type of plants are distributed in different areas. In order to adapt to different environments, their genetic genes will undergo different changes during the evolution process, and there will be abundant natural mutations, thus maintaining various types of flowering. This phenomenon is very common in the model plant Arabidopsis thaliana and is an important feature of genetic diversity.

Studies have found that FRIGIDA (FRI) and FLOWERING LOCUS C (FLC) are two key genes that inhibit plant flowering. For example, the reason why winter wheat needs to survive the winter is mainly because the homologous gene expression level of FRI and FLC is very high, which inhibits the flowering of winter wheat. After a long period of low temperature in autumn and winter, the FLC expression level will slowly decline. When the next spring, with the gradual increase in temperature, winter wheat can blossom and bear fruit. At the same time, only when FRI and FLC coexist, can they exert the function of inhibiting flowering. The loss of any gene will cause early flowering of plants.

In different types of Arabidopsis, the expression level of FLC is very different. Li Peijin’s research team conducted a quantitative analysis of the FLC gene expression levels of 102 species of Arabidopsis thaliana worldwide, and screened out a key gene SSF that regulates the flowering period through genome-wide association analysis. The protein encoded by the SSF gene is responsible for the function of regulating flowering. Through further research, it is found that the protein encoded by the SSF gene has two variant types-SSF414D and SSF414N. The widespread protein ubiquitination modification and degradation system in plants can recognize these two proteins and regulate the level of SSF protein, thereby affecting the expression level of the flowering suppressor gene FLC, leading to changes in plant flowering.

Li Peijin explained that the two variants of the SSF gene are amazing. Although SSF414D and SSF414N can inhibit the flowering of plants, the function of 414D is stronger and more obvious, while the performance of 414N is relatively insignificant.

In previous studies, the SSF gene has been discovered many times, but how this gene functions has been unclear, and the molecular regulation mechanism is even unknown. This research result has solved this problem for the first time and revealed in-depth that natural genetic variation regulates plant growth. The new mechanism of the period provides important genetic resources and theoretical basis for plant breeding.