Unfolding plant desiccation tolerance : evolution, structure, and function of LEA proteins

Abstract

Living beings comprise a whole sequence of levels forming [such] a hierarchy. (…) Each level relies for its operations on all the levels below it. Each reduces the scope of the one immediately below it by imposing on it a boundary that harnesses it to the service of the next-higher level, and this control is transmitted stage by stage, down to the basic inanimate level. (...) Each separate level of existence is of course interesting in itself and can be studied in itself." (Polanyi, 1968) "The ability to reduce everything to simple fundamental laws does not imply the ability to start from those laws and reconstruct the universe. (…) At each stage entirely new laws, concepts, and generalizations are necessary, requiring inspiration and creativity to just as great a degree as in the previous one. We expect to encounter fascinating and, I believe, very fundamental questions at each stage in fitting together less complicated pieces into the more complicated system and understanding the basically new types of behaviour which can result." (Anderson, 1972) In the research field of desiccation tolerance (DT), we aim to 'unfold' the different underpinnings of life without water in tolerant plant species in order to 'unlock' this process in non-tolerant species. The idea of 'unlocking' DT arises in a context where food productivity and security are increasingly challenged by environmental changes such as increased drought, while the world population is predicted to steadily grow to over 8.3 billion of people in the year 2030 (FAO, 2017). In the development of new technologies to tackle these challenges, raising 'basic' questions and conducting fundamental research are of pivotal importance. In this thesis I will present results of a study encompassing genomics, evolution, protein biochemistry, and molecular biology, and then go to a more general and speculative discussion of the main findings. Such a multilevel approach can aid to the comprehension of the complexity of the different levels that the process of DT involves, and can provide transferrable knowledge to produce more stress-tolerant crops.

Late Embryogenesis Abundant Proteins Contribute to the Resistance of Toxoplasma gondii Oocysts against Environmental Stresses

“…This allows LEA proteins to have antiaggregation, protein stabilization, as well as molecular chaperone-like activities ( 39 , 41 , 43 , 44 ). It translates into a redirection of water molecules, binding of salt ions, elimination of active oxygen free radicals, prevention of the cell structure collapse, and repair of misassembled proteins, among others ( 45 , 46 ).…”