Raman developmental markers in root cell walls are associated with lodging tendency in tef

Abstract Tef ( Eragrostis tef (Zucc.) Trotter) is an important staple crop in Ethiopia and Eritrea. Its grains are gluten-free and protein rich, so it is considered as a “super-food”. Adapting tef to modern farming practices could allow its intensive growth in other regions and enable larger communities to gain from its nutritional values. However, high lodging susceptibility prevents the application of mechanical harvest and causes significant yield losses. Lodging describes the displacement of roots (root lodging) or fracture of culms (stem lodging), forcing plants to bend or fall from their vertical position. Lodging is facilitated by various abiotic and biotic factors, and the lodging severity is increased in overpopulated fields. In this study, we aimed to understand the microstructural properties of crown roots, underlining tef tolerance/susceptibility to lodging. We analyzed plants at 5 and 10 weeks after emergence and compared trellised to lodged plants. Root cross sections from different tef genotypes were characterized by scanning electron microscopy, micro computed tomography and Raman micro spectroscopy. Lodging susceptible genotypes exhibited early tissue maturation, including developed aerenchyma, intensive lignification, and lignin with high levels of crosslinks. A comparison between trellised and lodged plants suggested that lodging itself does not affect the histology of root tissue. Furthermore, cell wall composition along plant maturation was typical to each of the tested genotypes independently of trellising. Our results suggest that it is possible to select lines that exhibit slow maturation of crown roots. Such lines are predicted to show reduction in lodging and facilitate mechanical harvest.