Fiona Smith (Martin-Luther-Universität Halle-Wittenberg)
Fiona Smith's Master thesis was awarded with the Prize for the Best Plant Science Master Thesis, which was carried out at Halle University in the year 2025 with the title:
Investigation of the interaction of ATG8 isoforms with AtCAN1 in planta
Smith investigated the interaction between a newly identified Component of the plant Autophagy Network, AtCAN1, and all nine ATG8 isoforms in Arabidopsis thaliana, guided by predicted ATG8-interaction motifs (AIMs) within the CAN1 sequence. Her findings reveal that CAN1 selectively binds specific ATG8 isoforms in an AIM-dependent manner and can form homodimers—insights that open new avenues for understanding CAN1 function in plant autophagy.
Autophagy is a cellular recycling process in which damaged or dysfunctional organelles and proteins are targeted for degradation in the vacuole via autophagosomes. This conserved mechanism enables nutrient recovery and allows eukaryotic cells to rapidly adapt to stress and changing environmental conditions. Cargo destined for degradation interacts with ATG8 either directly through ATG8-interaction motifs (AIMs) or indirectly via autophagy receptors, which recognize the cargo and present an AIM for ATG8 binding.
In her master’s thesis, Smith examined the role of the uncharacterized autophagy component AtCAN1 in plants. Using transient expression in Nicotiana benthamiana combined with co-immunoprecipitation, she demonstrated that AtCAN1 co-localizes and interacts in planta with all nine Arabidopsis ATG8 isoforms. The interaction relies on two of the five predicted ATG8-interaction motifs (AIM4 and AIM5) in AtCAN1 and varies among ATG8 isoforms, revealing isoform-specific modulation. Furthermore, Smith confirmed a proposed homodimerization of AtCAN1 both in a yeast two-hybrid system and biochemically in planta. These findings provide new insights into the molecular mechanisms of plant autophagy and broaden our understanding of the plant-specific CAN1 protein in relation to the functional diversity of ATG8 isoforms. By uncovering these interaction patterns, her work lays the foundation for future studies on how selective autophagy contributes to stress adaptation and cellular homeostasis in plants.
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Fiona Smith conducted this work at the Leibniz Institute of Plant Biochemistry in the working group of Dr. Christin Naumann, under the supervision of David Görg, as part of the DFG-funded AUTOPHO project and in association with the Research Training Group 2498.