MAIN CONCLUSION: The histone acetyltransferase GCN5 and associated transcriptional coactivator ADA2b are required to couple endoreduplication and trichome branching. Mutation of ADA2b also disrupts the relationship between ploidy and leaf cell size. Dynamic chromatin structure has been established as a general mechanism by which gene function is temporally and spatially regulated, but specific chromatin modifier function is less well understood. To address this question, we have investigated the role of the histone acetyltransferase GCN5 and the associated coactivator ADA2b in developmental events in Arabidopsis thaliana. Arabidopsis plants with T-DNA insertions in GCN5 (also known as HAG1) or ADA2b (also known as PROPORZ1) display pleiotropic phenotypes including dwarfism and floral defects affecting fertility. We undertook a detailed characterization of gcn5 and ada2b phenotypic effects in rosette leaves and trichomes to establish a role for epigenetic control in these developmental processes. ADA2b and GCN5 play specific roles in leaf tissue, affecting cell growth and division in rosette leaves often in complex and even opposite directions. Leaves of gcn5 plants display overall reduced ploidy levels, while ada2b-1 leaves show increased ploidy. Endoreduplication leading to increased ploidy is also known to contribute to normal trichome morphogenesis. We demonstrate that gcn5 and ada2b mutants display alterations in the number and patterning of trichome branches, with ada2b-1 and gcn5-1 trichomes being significantly less branched, while gcn5-6 trichomes show increased branching. Elongation of the trichome stalk and branches also vary in different mutant backgrounds, with stalk length having an inverse relationship with branch number. Taken together, our data indicate that, in Arabidopsis, leaves and trichomes ADA2b and GCN5 are required to couple nuclear content with cell growth and morphogenesis.
MAIN CONCLUSION: The histone acetyltransferase GCN5 and associated transcriptional coactivator ADA2b are required to couple endoreduplication and trichome branching. Mutation of ADA2b also disrupts the relationship between ploidy and leaf cell size. Dynamic chromatin structure has been established as a general mechanism by which gene function is temporally and spatially regulated, but specific chromatin modifier function is less well understood. To address this question, we have investigated the role of the histone acetyltransferase GCN5 and the associated coactivator ADA2b in developmental events in Arabidopsis thaliana. Arabidopsis plants with T-DNA insertions in GCN5 (also known as HAG1) or ADA2b (also known as PROPORZ1) display pleiotropic phenotypes including dwarfism and floral defects affecting fertility. We undertook a detailed characterization of gcn5 and ada2b phenotypic effects in rosette leaves and trichomes to establish a role for epigenetic control in these developmental processes. ADA2b and GCN5 play specific roles in leaf tissue, affecting cell growth and division in rosette leaves often in complex and even opposite directions. Leaves of gcn5 plants display overall reduced ploidy levels, while ada2b-1 leaves show increased ploidy. Endoreduplication leading to increased ploidy is also known to contribute to normal trichome morphogenesis. We demonstrate that gcn5 and ada2b mutants display alterations in the number and patterning of trichome branches, with ada2b-1 and gcn5-1 trichomes being significantly less branched, while gcn5-6 trichomes show increased branching. Elongation of the trichome stalk and branches also vary in different mutant backgrounds, with stalk length having an inverse relationship with branch number. Taken together, our data indicate that, in Arabidopsis, leaves and trichomes ADA2b and GCN5 are required to couple nuclear content with cell growth and morphogenesis.
Authors: José M Alonso; Anna N Stepanova; Thomas J Leisse; Christopher J Kim; Huaming Chen; Paul Shinn; Denise K Stevenson; Justin Zimmerman; Pascual Barajas; Rosa Cheuk; Carmelita Gadrinab; Collen Heller; Albert Jeske; Eric Koesema; Cristina C Meyers; Holly Parker; Lance Prednis; Yasser Ansari; Nathan Choy; Hashim Deen; Michael Geralt; Nisha Hazari; Emily Hom; Meagan Karnes; Celene Mulholland; Ral Ndubaku; Ian Schmidt; Plinio Guzman; Laura Aguilar-Henonin; Markus Schmid; Detlef Weigel; David E Carter; Trudy Marchand; Eddy Risseeuw; Debra Brogden; Albana Zeko; William L Crosby; Charles C Berry; Joseph R Ecker Journal: Science Date: 2003-08-01 Impact factor: 47.728
Authors: Moussa Benhamed; Marie-Laure Martin-Magniette; Ludivine Taconnat; Frédérique Bitton; Caroline Servet; Rebecca De Clercq; Björn De Meyer; Caroline Buysschaert; Stéphane Rombauts; Raimundo Villarroel; Sébastien Aubourg; Jim Beynon; Rishikesh P Bhalerao; George Coupland; Wilhelm Gruissem; Frank L H Menke; Bernd Weisshaar; Jean-Pierre Renou; Dao-Xiu Zhou; Pierre Hilson Journal: Plant J Date: 2008-09-18 Impact factor: 6.417