期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2012
卷号：109
期号：40
页码：16360-16365
DOI：10.1073/pnas.1202041109
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Environmental stress often leads to an increased production of reactive oxygen species that are involved in plastid-to-nucleus retrograde signaling. Soon after the release of singlet oxygen (1O2) in chloroplasts of the flu mutant of Arabidopsis, reprogramming of nuclear gene expression reveals a rapid transfer of signals from the plastid to the nucleus. We have identified extraplastidic signaling constituents involved in 1O2-initiated plastid-to-nucleus signaling and nuclear gene activation after mutagenizing a flu line expressing the luciferase reporter gene under the control of the promoter of a 1O2-responsive AAA-ATPase gene (At3g28580) and isolating second-site mutations that lead to a constitutive up-regulation of the reporter gene or abrogate its 1O2-dependent up-regulation. One of these mutants, caa39, turned out to be a weak mutant allele of the Topoisomerase VI (Topo VI) A-subunit gene with a single amino acid substitution. Transcript profile analysis of flu and flu caa39 mutants revealed that Topo VI is necessary for the full activation of AAA-ATPase and a set of 1O2-responsive transcripts in response to 1O2. Topo VI binds to the promoter of the AAA-ATPase and other 1O2-responsive genes, and hence could directly regulate their expression. Under photoinhibitory stress conditions, which enhance the production of 1O2 and H2O2, Topo VI regulates 1O2-responsive and H2O2-responsive genes in a distinct manner. These results suggest that Topo VI acts as an integrator of multiple signals generated by reactive oxygen species formed in plants under adverse environmental conditions.
