Biology subjects

Elbaum, R.

Publications and source records attributed to Elbaum, R..

3 recordsLinked to original sources

bioRxiv2023

RAMAN DEVELOPMENTAL MARKERS IN ROOT CELL WALLS ARE ASSOCIATED WITH LODGING TENDENCY IN TEF

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.

plant biology↗

bioRxiv2021

Hydrogen peroxide modulates lignin and silica deposits in sorghum roots

Hydrated silica (SiO2{middle dot}nH2O) aggregates in the root endodermis of grasses. Application of soluble silicates (Si) to roots is associated with variations in the balance of reactive oxygen species (ROS), increased tolerance to a broad range of stresses affecting ROS levels, and early lignin deposition. In sorghum (Sorghum bicolor L.), silica aggregation is patterned in an active silicification zone (ASZ) by a special type of lignin. Since lignin polymerization is mediated by ROS, we studied the formation of root lignin and silica under varied conditions of ROS by modulating hydrogen peroxide (H2O2) concentration in the growth solution. Sorghum seedlings were grown hydroponically and supplemented with Si, H2O2, and KI, a salt that catalyzes H2O2 decomposition. Lignin and silica deposits in the endodermis were studied by histology, scanning electron and Raman microscopies. Cell wall composition was quantified by thermal gravimetric analysis. We found that the endodermal H2O2 concentration regulated the extent of ASZ lignin deposition along the root, but not its patterning in spots. Our results show that ASZ lignin is necessary for root silica aggregation in sorghum, and that silicification is enhanced under oxidative stress as a result of increased deposition of the ASZ lignin. One sentence summaryLignin with carbonyl modifications is patterned by the activity of H2O2 to nucleate silica aggregations in sorghum roots.

plant biology↗

bioRxiv2019

Grass silica mineralizer (GSM1) protein precipitates silica in sorghum silica cells

O_LISilicon is absorbed by plant roots as silicic acid. The acid moves with the transpiration stream to the shoot, and mineralizes as silica. In grasses, leaf epidermal cells called silica cells deposit silica in most of their volume by unknown mechanism.\nC_LIO_LIUsing bioinformatics tools, we identified a previously uncharacterized protein in sorghum (Sorghum bicolor), which we named Siliplant1 (Slp1). Silica precipitation activity in vitro, expression profile, and activity in precipitating biosilica in vivo were characterized.\nC_LIO_LISlp1 is a basic protein with seven repeat units rich in proline, lysine, and glutamic acid. A short peptide, repeating five times in the protein precipitated silica in vitro at a biologically relevant silicic acid concentration. Raman and NMR spectroscopies showed that the peptide attached the silica through lysine amine groups, forming a mineral-peptide open structure. We found Slp1 expression in immature leaf and inflorescence tissues. In the immature leaf active silicification zone, Slp1 was localized to the cytoplasm or near cell boundaries of silica cells. It was packed in vesicles and secreted to the paramural space. Transient overexpression of Slp1 in sorghum resulted in ectopic silica deposition in all leaf epidermal cell types.\nC_LIO_LIOur results show that Slp1 precipitates silica in sorghum silica cells.\nC_LI

plant biology↗