The role of pseudo-proteases during drought tolerance of plants - Christiane funk

Proteases are proteins that break down other proteins. They are involved in many different biological functions, e.g. the digestion of our food, cleaning the cell from malfunctioning proteins or cell signaling. Even though hundreds of proteases are encoded in the genomes of various plants, their biological roles are mostly unknown.

Using molecular biological and biochemical methods, we try to identify the function of a family of proteases called FtsH proteases. They are localized in mitochondria of humans, animals, plants and bacteria; in plants they can even be found in the chloroplast. While humans only have very few of these FtsH proteases, the model plant Arabidopsis thaliana contains 13 FtsH enzymes and the tree Populus has even 16 members.

Interestingly, five of the chloroplast-located FtsH homologues of A. thaliana have mutations rendering them presumably proteolytic inactive, they therefore are called pseudo-proteases. To our surprise we found one of these pseudo-proteases, FtsHi3, to be involved in drought tolerance of plants.

The research team of Prof. Christiane Funk at Umeå University and the R&D team of Dr Sacha Escamez at SweTree Technologies AB are partnering to understand how FtsHi3 could be leveraged to produce drought resistant crops. Proof of concept experiments in Arabidopsis suggested that transgenic overexpression of FtsHi3 could provide the plants with both better growth rate and improved drought tolerance, which is a very rare and very desirable combination.

This project would consist in further exploring how to optimize overexpression of FtsHi3, by using different promoters for its overexpression to become either inducible, or tissue-specific. Firstly, already transformed transgenic lines would be screened to identify the ones being homozygous for the transgene. Secondly, the expected (over)expression of the FtsHi3 gene would be tested by real-time quantitative PCR (qPCR), in regular growth conditions and during drought. Thirdly, the effect of the different overexpression strategies for FtsHi3 would be tested through drought experiments. Finally, conservation of the expected drought tolerance via FtsHi3 overexpression would be tested in Populus trees, to find if FtsHi3 overexpression could be applicable to wood crops.