title: Drought response transcriptomes are altered in poplar with reduced tonoplast sucrose transporter expression.
abstract: Transgenic Populus tremula x alba (717-1B4) plants with reduced expression of a tonoplast sucrose efflux transporter, PtaSUT4, exhibit reduced shoot growth compared to wild type (WT) under sustained mild drought. The present study was undertaken to determine whether SUT4-RNAi directly or indirectly altered poplar predisposition and/or response to changes in soil water availability. While sucrose and hexose levels were constitutively elevated in shoot organs, expression responses to drought were most altered in the root tips of SUT4-RNAi plants. Prior to any drought treatment, constitutively elevated transcript levels of abscisic acid biosynthetic genes and bark/vegetative storage proteins suggested altered metabolism in root tips of RNAi plants. Stronger drought-stimulation of stress-inducible genes encoding late-embryogenesis-abundant proteins in transgenic roots was consistent with increased vulnerability to soil drying. Transcript evidence suggested an RNAi effect on intercellular water trafficking by aquaporins in stem xylem during soil drying and recovery. Co-expression network analysis predicted altered integration of abscisic acid sensing/signaling with ethylene and jasmonate sensing/signaling in RNAi compared to WT roots. The overall conclusion is that steepened shoot-root sugar gradient in RNAi plants increased sensitivity of root tips to decreasing soil water availability.
authors.affiliation: Warnell School of Forestry and Natural Resources and Department of Genetics, University of Georgia, Athens, GA 30602, USA.
authors.forename: Liang-Jiao
authors.initials: LJ
authors.lastname: Xue
authors.affiliation: Warnell School of Forestry and Natural Resources and Department of Genetics, University of Georgia, Athens, GA 30602, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Frost
authors.affiliation: Warnell School of Forestry and Natural Resources and Department of Genetics, University of Georgia, Athens, GA 30602, USA.
authors.forename: Chung-Jui
authors.initials: CJ
authors.lastname: Tsai
authors.affiliation: Warnell School of Forestry and Natural Resources and Department of Genetics, University of Georgia, Athens, GA 30602, USA.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Harding
mesh_terms: D055864:Droughts; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks; D026901:Membrane Transport Proteins / Q000235:genetics*; D009928:Organ Specificity; D010940:Plant Proteins / Q000235:genetics*; D018517:Plant Roots; D018520:Plant Shoots; D030821:Plants, Genetically Modified; D032107:Populus / Q000502:physiology*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D013395:Sucrose / Q000378:metabolism*; D059467:Transcriptome
chemical_list: D026901:Membrane Transport Proteins; D010940:Plant Proteins; D034741:RNA, Small Interfering; C078729:sucrose transport protein, plant; D013395:Sucrose