TY - JOUR A1 - Brzezinka, Krzysztof A1 - Altmann, Simone A1 - Czesnick, Hjördis A1 - Nicolas, Philippe A1 - Gorka, Michal A1 - Benke, Eileen A1 - Kabelitz, Tina A1 - Jähne, Felix A1 - Graf, Alexander A1 - Kappel, Christian A1 - Bäurle, Isabel T1 - Arabidopsis FORGETTER1 mediates stress-induced chromatin memory through nucleosome remodeling JF - eLife N2 - Plants as sessile organisms can adapt to environmental stress to mitigate its adverse effects. As part of such adaptation they maintain an active memory of heat stress for several days that promotes a more efficient response to recurring stress. We show that this heat stress memory requires the activity of the FORGETTER1 (FGT1) locus, with fgt1 mutants displaying reduced maintenance of heat-induced gene expression. FGT1 encodes the Arabidopsis thaliana orthologue of Strawberry notch (Sno), and the protein globally associates with the promoter regions of actively expressed genes in a heat-dependent fashion. FGT1 interacts with chromatin remodelers of the SWI/ SNF and ISWI families, which also display reduced heat stress memory. Genomic targets of the BRM remodeler overlap significantly with FGT1 targets. Accordingly, nucleosome dynamics at loci with altered maintenance of heat-induced expression are affected in fgt1. Together, our results suggest that by modulating nucleosome occupancy, FGT1 mediates stress-induced chromatin memory. Y1 - 2016 U6 - https://doi.org/10.7554/eLife.17061 SN - 2050-084X VL - 5 PB - eLife Sciences Publications CY - Cambridge ER - TY - JOUR A1 - Czesnick, Hjördis A1 - Lenhard, Michael T1 - Antagonistic control of flowering time by functionally specialized poly(A) polymerases in Arabidopsis thaliana JF - The plant journal N2 - Polyadenylation is a critical 3-end processing step during maturation of pre-mRNAs, and the length of the poly(A) tail affects mRNA stability, nuclear export and translation efficiency. The Arabidopsis thaliana genome encodes three canonical nuclear poly(A) polymerase (PAPS) isoforms fulfilling specialized functions, as reflected by their different mutant phenotypes. While PAPS1 affects several processes, such as the immune response, organ growth and male gametophyte development, the roles of PAPS2 and PAPS4 are largely unknown. Here we demonstrate that PAPS2 and PAPS4 promote flowering in a partially redundant manner. The enzymes act antagonistically to PAPS1, which delays the transition to flowering. The opposite flowering-time phenotypes in paps1 and paps2 paps4 mutants are at least partly due to decreased or increased FLC activity, respectively. In contrast to paps2 paps4 mutants, plants with increased PAPS4 activity flower earlier than the wild-type, concomitant with reduced FLC expression. Double mutant analyses suggest that PAPS2 and PAPS4 act independently of the autonomous pathway components FCA, FY and CstF64. The direct polyadenylation targets of the three PAPS isoforms that mediate their effects on flowering time do not include FLC sense mRNA and remain to be identified. Thus, our results uncover a role for canonical PAPS isoforms in flowering-time control, raising the possibility that modulating the balance of the isoform activities could be used to fine tune the transition to flowering. Significance Statement The length of the poly(A) tail affects mRNA stability, nuclear export and translation efficiency. Arabidopsis has three isoforms of nuclear poly(A) polymerase (PAPS): PAPS1 plays a major role in organ growth and plant defence. Here we show that PAPS2 and PAPS4 redundantly promote flowering and act antagonistically to PAPS1, which delays flowering. We suggest that modulating the activity of these isoforms fine-tunes the transition to flowering. KW - polyadenylation KW - 3-end processing KW - poly(A) polymerase KW - flowering time KW - autonomous pathway KW - Arabidopsis thaliana Y1 - 2016 U6 - https://doi.org/10.1111/tpj.13280 SN - 0960-7412 SN - 1365-313X VL - 88 SP - 570 EP - 583 PB - Wiley-Blackwell CY - Hoboken ER -