I have always been deeply fascinated by studying how plants perceive and respond to environmental stimuli. This passion led me to undertake a thesis project on the molecular response of Arabidopsis thaliana to low oxygen (hypoxic) conditions, which frequently hamper crop production during floodings. After completing my master’s degree in Environmental and Agricultural Biotechnology at the University of Florence (Italy), I spent a year on a research project on the contribution of an endophytic fungus to tomato drought tolerance. My deep interest in plants has induced me to move to Ghent, where I have started a PhD research project which aims to investigate how light inhibits adventitious rooting.
The plant root system supports essential functions such as the uptake of water and nutrients, the anchoring and the synergistic interactions with the soil microbiome. In addition to the primary root with branches along its grown axis (lateral roots), plants can develop adventitious roots (ARs) in response to abiotic or biotic stresses. Such endogenous capacity is of primary importance for fast clonal propagation in professional horticulture as it uses AR formation in stem cuttings. Rooting powders containing auxin trigger AR formation in stem cuttings. Some recalcitrant species also require additional treatment in the dark for several days to improve rooting. It is currently unclear how a dark treatment increases AR or, vice versa, how light inhibits AR formation.
In Arabidopsis thaliana, dark-grown (etiolated) seedlings develop hypocotyl elongation, apical hook formation and ARs from the hypocotyl. Contrarily, seedlings that grow in the light do not produce ARs. The research identified several molecular actors involved in AR formation in Arabidopsis. In the dark, the COP1 E3 ligase indirectly stabilises PHYTOCHROME INTERACTING FACTORS (PIFs) transcription factors by degrading the stimulators of photomorphogenesis ELONGATED HYPOCOTYL5 (HY5) and HY5-HOMOLOG (HYH). In the light, HY5 and HY5 are active and start nuclear reprogramming. pifQ and hy5 mutants developed fewer and larger ARs than wild-type, respectively. However, the mechanism by which light inhibits AR formation is poorly understood. In vitro cultivated shoots are temporally incubated in the dark to avoid the light-inhibiting effect. Unfortunately, this technique is not always feasible with cuttings grown in nurseries. By analysing several light mutants, my PhD project aims to unravel the complex and interconnected network of signalling elements by which light regulates AR formation.