title: Photosynthetic acclimation is reflected in specific patterns of gene expression in drought-stressed loblolly pine.
abstract: Because the product of a single gene can influence many aspects of plant growth and development, it is necessary to understand how gene products act in concert and upon each other to effect adaptive changes to stressful conditions. We conducted experiments to improve our understanding of the responses of loblolly pine (Pinus taeda) to drought stress. Water was withheld from rooted plantlets of to a measured water potential of -1 MPa for mild stress and -1.5 MPa for severe stress. Net photosynthesis was measured for each level of stress. RNA was isolated from needles and used in hybridizations against a microarray consisting of 2173 cDNA clones from five pine expressed sequence tag libraries. Gene expression was estimated using a two-stage mixed linear model. Subsequently, data mining via inductive logic programming identified rules (relationships) among gene expression, treatments, and functional categories. Changes in RNA transcript profiles of loblolly pine due to drought stress were correlated with physiological data reflecting photosynthetic acclimation to mild stress or photosynthetic failure during severe stress. Analysis of transcript profiles indicated that there are distinct patterns of expression related to the two levels of stress. Genes encoding heat shock proteins, late embryogenic-abundant proteins, enzymes from the aromatic acid and flavonoid biosynthetic pathways, and from carbon metabolism showed distinctive responses associated with acclimation. Five genes shown to have different transcript levels in response to either mild or severe stress were chosen for further analysis using real-time polymerase chain reaction. The real-time polymerase chain reaction results were in good agreement with those obtained on microarrays.
authors.affiliation: Department of Plant Pathology, Virginia Tech, Blacksburg, Virginia 24061, USA.
authors.forename: Jonathan I
authors.initials: JI
authors.lastname: Watkinson
authors.forename: Allan A
authors.initials: AA
authors.lastname: Sioson
authors.forename: Cecilia
authors.initials: C
authors.lastname: Vasquez-Robinet
authors.forename: Maulik
authors.initials: M
authors.lastname: Shukla
authors.forename: Deept
authors.initials: D
authors.lastname: Kumar
authors.forename: Margaret
authors.initials: M
authors.lastname: Ellis
authors.forename: Lenwood S
authors.initials: LS
authors.lastname: Heath
authors.forename: Naren
authors.initials: N
authors.lastname: Ramakrishnan
authors.forename: Boris
authors.initials: B
authors.lastname: Chevone
authors.forename: Layne T
authors.initials: LT
authors.lastname: Watson
authors.forename: Leonel
authors.initials: L
authors.lastname: van Zyl
authors.forename: Ulrika
authors.initials: U
authors.lastname: Egertsdotter
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Sederoff
authors.forename: Ruth
authors.initials: R
authors.lastname: Grene
mesh_terms: D000064:Acclimatization / Q000235:genetics*; D019295:Computational Biology / Q000379:methods*; D004190:Disasters; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000235:genetics; D010788:Photosynthesis / Q000502:physiology*; D041603:Pinus taeda / Q000235:genetics* / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics
chemical_list: D006360:Heat-Shock Proteins; D010940:Plant Proteins; D018749:RNA, Plant