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Project

The effects of ambient temperature on Brachypodium distachyon development and mRNA binding proteins in flowering plants

Global temperature has been predicted to increase by 1.8°C to 4°C by the end of this century. This minor change in temperature could cause an average 4% decrease in crop yield. Therefore, understanding how crops react to this minor temperature change is important to predict the impact on crop yield. Plant research based on the model plant Arabidopsis thaliana has broadened our knowledge of molecular biology in plants, but Arabidopsis has limitations when used as a temperate grass model when one wants to explore grass specific characteristics. Brachypodium distachyon has become a model for temperate grasses such as wheat and barley because of its smaller genome, relative ease to manipulate in the lab and available mutants. Therefore, in this work, we used Brachypodium as a model to explore the temperature effects on plant development.

Firstly, we explored the ambient temperature effects on five different Brachypodium accessions through growing the plants at 14°C, 18°C and 22°C. The flowering time, leaf and branch numbers when flowering, seed set period, seed weight and size, and seed dormancy were recorded. We have shown that the seed development stage is more sensitive to the changing temperature than flowering time, and seed weight is negatively correlated to elevated temperatures.  

Secondly, the mutant lines of FLC homologs and SVP homologs in Brachypodium were phenotyped at different temperature conditions because of the important roles of FLM and SVP genes in ambient temperature regulation in Arabidopsis. We found that one mutant of the SVP homologs in Brachypodium, BdVRT2 T-DNA line, has delayed flowering at higher ambient temperature.

Thirdly, the function of BdVRT2 in Brachypodium was studied more deeply in this work. We found that BdVRT2 is upregulated during cold treatment and the mutant line delayed flowering in vernalized condition. This indicated that BdVRT2 promotes the transition to flowering in vernalization. In addition, BdVRT2 showed similar expression patterns as the key floral promoter BdVRN1. The interaction of BdVRT2 and BdVRN1 were shown through yeast-two hybrid assay, GSP pull-down assay and BiFC in leaf mesophyll protoplasts.

Fourthly, one side project was to explore the possible function of one of FLC homologs, BdODDSOC1, in Brachypodium. The mutant lines were phenotyped in different conditions combining daylength and vernalization, but no interesting phenotype has been found except a minor difference in leaf numbers when flowering. The leaf development in the same conditions was phenotyped, and the mutant line of the BdODDSOC1 T-DNA showed a faster rate of leaf development. It appears the single function of BdODDSOC1 is minor. The freezing tolerance experiment was tested survival rate of BdODDSOC1 T-DNA  and WT in cold temperature, which resulted in the possible role of BdODDSOC1 to protect the seedlings from frost stress.

The last project I did was to capture the RNA binding proteins with a modified RNA interactome capture method in Brachypodium. This method was applied to Brachypodium shoot and leaf mesophyll protoplasts successfully, and we identified 405 RBPs. However, the validation of these captured proteins remained an issue.

In conclusion, the results indicate that the reproductive stage in Brachypodium development is more sensitive to different temperatures than the floral transition stage. We showed that BdVRT2 is a floral promoter in vernalization regulation. Also, we captured 405 RBPs in Brachypodium shoot and leaf mesophyll protoplasts and pointed out the limitation of RNA interactome capture method.

Date:1 Sep 2015 →  27 Nov 2019
Keywords:Brachypodium distachyon, ambient temperature, RNA binding proteins
Disciplines:Plant biology, General biology, Agricultural plant production, Horticultural production, Biomaterials engineering, Biological system engineering, Biomechanical engineering, Other (bio)medical engineering, Environmental engineering and biotechnology, Industrial biotechnology, Other biotechnology, bio-engineering and biosystem engineering
Project type:PhD project