Murugaiyan, V. | bioRxiv Science

bioRxiv2022

Defining transcription factor nucleosome binding with Pioneer-seq

Gene expression requires the targeting of transcription factors (TFs) to regulatory sequences often occluded within nucleosomes. To comprehensively examine TF nucleosome binding, we developed Pioneer-Seq. In Pioneer-seq a library of nucleosomes containing thousands of DNA sequences with TF binding sites in all possible nucleosome orientations is bound to a TF and the protein-nucleosome complex is isolated and quantified. To demonstrate Pioneer-seq we examined nucleosome binding by OCT4, SOX2, KLF4, and c-MYC. Our results demonstrate that KLF4 and SOX2 can bind close to the nucleosome dyad with nucleosome sequence being the major factor regulating TF binding across all studied TFs.

molecular biology↗

bioRxiv2020

Introgression from Oryza meridionalis into domesticated rice Oryza sativa results in shoot-based iron tolerance

Iron (Fe) toxicity is one of the most common mineral disorders affecting rice (Oryza sativa) production in flooded lowland fields. Oryza meridionalis is endemic from Northern Australia and grows in regions with Fe rich soils, making it a candidate for use in adaptive breeding. Aiming to understand tolerance mechanisms in rice, we screened a population of interspecific introgression lines (IL) from a cross between O. sativa and O. meridionalis for the identification of QTLs contributing to Fe toxicity tolerance. Six putative QTLs were identified. A line carrying one introgression from O. meridionalis on chromosome 9 associated with one QTL was highly tolerant despite very high shoot Fe concentrations. Physiological, biochemical, ionomic and transcriptomic analyses showed that the IL tolerance could partly be explained by Fe retention in the leaf sheath and culm. We constructed the interspecific hybrid genome in silico for transcriptomic analysis, and identified differentially regulated introgressed genes from O. meridionalis that could be involved in shoot-based Fe tolerance, such as metallothioneins, glutathione S-transferases and transporters from ABC and MFS families. This is the first work to demonstrate that introgressions of O. meridionalis into the O. sativa genome can confer increased tolerance to excess Fe. HighlightWe identified QTLs associated with iron tolerance derived from O. meridionalis, and characterized their physiological basis in O. sativa.

plant biology↗