Cay Christin Schäfer (Universität Bonn)
Cay Christin Schäfer's Master thesis was awarded with the Prize for the Best Plant Science Master Thesis, which was carried out at Universität Bonn in the year 2024 with the title:
Crosstalk between the micronutrient boron and the phytohormone auxin on the level of polar auxin transport during primary root development of maize (Zea mays)
The polar localisation of the auxin transport protein PINFORMED1a in the maize root is altered under boron deficiency. This reveals that auxin transport is an important regulator of plant growth under boron deficiency. Schäfer's work supports the hypothesis that there is an interaction between boron and auxin on the level of polar auxin transport in the primary root of maize, making auxin an important factor regulating growth responses under boron deficiency in plants.
All essential nutrients are required in sufficient amounts for optimal plant growth. The micronutrient boron is one of these nutrients and is taken up by plants through the roots in form of boric acid. Many soils worldwide are deficient in boron, resulting in severe yield losses. To counteract these adverse effects, it is pivotal to understand the role of boron in plants. On the one hand, boron contributes to the stabilisation of the cell wall in plants. In addition, cell wall-independet functions of boron are suggested, such as interactions with plant hormones including auxin. Such interactions between boron and auxin were investigated in this master thesis in the crop plant maize. For this purpose, seedling assays were carried out in maize, firstly using a maize variety in which auxin transport is disrupted (Zmbarren inflorescence2). In addition, a chemical approach was applied using naphthylphthalamic acid (NPA), a chemical that inhibits auxin transport. Furthermore, cellular analyses with the fluorescent marker line ZmPINFORMED1a:YFP (ZmPIN1a:YFP) were performed to investigate the localisation of the auxin efflux transporter ZmPIN1a in the primary root of boron-deficient maize seedlings using confocal laser scanning microscopy. For all apporaches seedlings were grown under different boron conditions. These analyses aimed revealing a potential interaction between boron and auxin on the level of polar auxin transport and thus aid in further characterizing the role of boron in the plant. The mutant and the chemical approach using NPA provided no experimental evidence for interactions between boron and auxin transport during primary root development in maize. However, it was shown that boron deficiency leads to an altered localisation of the auxin efflux transporter ZmPIN1a:YFP, which may disrupt polar auxin transport and thus the establishment of auxin gradients. The results of this work support the hypothesis that interactions between boron and auxin play a role in maize primary root development. Further experiments should assess whether the delocalisation of the auxin efflux transporter occurs independently of cell wall defects.
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Cay Christin Schäfer conducted this work at the Institut für Nutzpflanzen und Ressourcenschutz - Crop Functional Genomics in the working group of Dr. Michaela Matthes in Professor Hochholdingers group.