Search

Aluminum‐dependent stoppage of root growth requires the DNA damage response (DDR) pathway including the p53‐like transcription factor SUPPRESSOR OF GAMMA RADIATION 1 (SOG1), which promotes terminal differentiation of the root tip in response to Al dependent cell death. Transcriptomic analyses identified Al‐induced SOG1‐regulated targets as candidate mediators of this growth arrest. Analysis of these factors either as loss‐of‐function mutants or by overexpression in the als3‐1 background shows ERF115, which is a key transcription factor that in other scenarios is rate‐limiting for damaged stem cell replenishment, instead participates in transition from an actively growing root to one that has terminally differentiated in response to Al toxicity. This is supported by a loss‐of‐function erf115 mutant raising the threshold of Al required to promote terminal differentiation of Al hypersensitive als3‐1. Consistent with its key role in stoppage of root growth, a putative ERF115 barley ortholog is also upregulated following Al exposure, suggesting a conserved role for this ATR‐dependent pathway in Al response. In contrast to other DNA damage agents, these results show that ERF115 and likely related family members are important determinants of terminal differentiation of the root tip following Al exposure and central outputs of the SOG1‐mediated pathway in Al response. Summary Statement: Aluminum dependent stoppage of root growth in Arabidopsis thaliana requires a SUPPRESSOR OF GAMMA RADIATION 1 controlled transcriptional program that includes ERF115 and family members. Loss of ERF114 and ERF115 results in prevention of the severe response to Al normally seen in the Al hyperresponsive mutant als3‐1. [ABSTRACT FROM AUTHOR]

We are in a period of transition in outer space: it is becoming increasingly congested. As one example, small satellites are beginning to interfere with astronomical observations. The objective of this article is to examine and evaluate how the various outer space interests interact, coordinate or conflict with each other. This article examines legal order options and the consequences of choosing among those options. Cite as: Paul B. Larsen, Outer Space: How Shall the World's Governments Establish Order Among Competing Interests?. 29 WASH. INT'L LJ. 1 (2019)., I. INTRODUCTION: WHY ORDER IN OUTER SPACE? Outer space seems unlimited; at least it so appeared in 1957 when Sputnik was launched. Since then, space activities have blossomed and many [...]