Kulikova, O. | Search bioRxiv

bioRxiv2020

Plant-specific histone deacetylases are essential for early as well as late stages of Medicago nodule development

Legume and rhizobium can establish a nitrogen-fixing nodule symbiosis. Previous studies have shown that several transcription factors that play a role in (lateral) root development are also involved in nodule development. Chromatin remodelling factors, like transcription factors, are key players in regulating gene expression. However, it has not been studied whether chromatin remodelling genes that are essential for root development get involved in nodule development. Here we studied the role of Medicago histone deacetylases (MtHDTs) in nodule development. Their Arabidopsis orthologs have been shown to play a role in root development. The expression of MtHDTs is induced in nodule primordia and is maintained in nodule meristem and infection zone. Conditional knock-down of their expression in a nodule-specific way by RNAi blocks nodule primordium development. A few nodules still can be formed but their nodule meristems are smaller and rhizobial colonization of the cells derived from the meristem is markedly reduced. Although the HDTs are expressed during nodule and root development, transcriptome analyses indicate that HDTs control the development of these organs in a different manner. During nodule development the MtHDTs positively regulate 3-hydroxy-3-methylglutaryl coenzyme a reductase 1 (MtHMGR1). The decreased expression of MtHMGR1 is sufficient to explain the block of primordium formation. ONE SENTENCE SUMMARYPlant-specific histone deacetylases regulate the expression of 3-hydroxy-3-methylglutaryl-coenzyme A reductases to control root nodule development.

developmental biology↗

bioRxiv2020

Sea-crossing along migratory flyways is limited more strongly by wind than by lack of uplift

Flying over the open sea is energetically costly for terrestrial birds. Despite this, over-water journeys of many birds, sometimes hundreds of kilometers long, are uncovered by bio-logging technology. To understand how these birds afford their flights over the open sea, we investigated the role of atmospheric conditions, specifically wind and uplift, in subsidizing over-water flight at the global scale. We first established that {Delta}T, the temperature difference between sea surface and air, is a meaningful proxy for uplift over water. Using this proxy, we showed that the spatio-temporal patterns of sea-crossing in terrestrial migratory birds is associated with favorable uplift conditions. We then analyzed route selection over the open sea for five facultative soaring species, representing all major migratory flyways. The birds maximized wind support when selecting their sea-crossing routes and selected higher uplift when suitable wind support was available. They also preferred routes with low long-term uncertainty in wind conditions. Our findings suggest that, in addition to wind, uplift may play a key role in the energy seascape for bird migration that in turn determines strategies and associated costs for birds crossing ecological barriers such as the open sea.

animal behavior and cognition↗