Winner of a grant from the Chinese Academy of Sciences, Qinwu Chen joined the Institute Jean-Pierre Bourgin (INRA-AgroParisTech-ELR CNRS) in October 2015 for a four-year period.
As holder of a Master's degree in agronomy from the Chinese Agricultural University, Q. Chen will thus be preparing a PhD in the Life Sciences. He will be working on the role of autophagy in nitrogen remobilisation and in the adaptation of plants to their environment.
Autophagy, a process essential to the longevity of eukaryote cells…
Autophagy is a cellular mechanism that allows organisms to efficiently recycle nutrients so as to ensure not only their growth and reproduction, but also their survival when the environment becomes unfavourable. In eukaryote organisms, autophagy contributes to longevity and cellular homeostasis by eliminating damaged proteins and failing organelles. This cleaning and recycling function is essential in plants; because of their immobility, they cannot move to a better environment when their surroundings have become hostile.
In Arabidopsis thaliana, autophagy is induced in the leaves during senescence and in grains during maturation. In the leaves, it is involved in eliminating and degrading the oxidised proteins that appear during ageing, when cellular functions are impaired. When oxidised proteins accumulate in a cell, they are sequestered by autophagic vesicles (autophagosomes) and delivered to the lytic vacuole that digests them. This process also contributes to the recycling of proteins, and hence that of nitrogen. Unable to recycle and mobilise their nitrogen reserves efficiently, autophagic mutants are thus hypersensitive to nitrogen restriction.
….and an excellent subject for a PhD project
Working in a team with an established international reputation regarding the remobilisation of nitrogen resources in response to environmental constraints and during cellular ageing, Q. Chen's objectives are to:
- transfer the knowledge acquired in A. thaliana to a plant of agronomic interest; using barley as his model, he will be studying the contribution of autophagy to grain filling, notably in response to a restriction of nitrate, one of the forms of nitrogen that is directly assimilable by plants;
- determine the substrates specific to autophagy in senescent leaves of A. thaliana;
- examine the alternative degradation processes put in place in senescent leaves, notably those associated with vacuolar proteolytic activities.
These are fascinating perspectives, and Q. Chen has already taken up the challenge with enthusiasm. More generally, his stay will allow him to improve his knowledge in the fields of both nitrogen nutrition and physiology of the whole plant. It will also enable him to acquire new tools and to learn French, a new language for him but one where he is already making remarkable progress. On returning to China, he hopes to pursue a university career while maintaining his links with INRA and his current host laboratory.