title: Drought-Induced Leaf Proteome Changes in Switchgrass Seedlings.
abstract: Switchgrass (Panicum virgatum) is a perennial crop producing deep roots and thus highly tolerant to soil water deficit conditions. However, seedling establishment in the field is very susceptible to prolonged and periodic drought stress. In this study, a "sandwich" system simulating a gradual water deletion process was developed. Switchgrass seedlings were subjected to a 20-day gradual drought treatment process when soil water tension was increased to 0.05 MPa (moderate drought stress) and leaf physiological properties had expressed significant alteration. Drought-induced changes in leaf proteomes were identified using the isobaric tags for relative and absolute quantitation (iTRAQ) labeling method followed by nano-scale liquid chromatography mass spectrometry (nano-LC-MS/MS) analysis. Additionally, total leaf proteins were processed using a combinatorial library of peptide ligands to enrich for lower abundance proteins. Both total proteins and those enriched samples were analyzed to increase the coverage of the quantitative proteomics analysis. A total of 7006 leaf proteins were identified, and 257 (4% of the leaf proteome) expressed a significant difference (p < 0.05, fold change <0.6 or >1.7) from the non-treated control to drought-treated conditions. These proteins are involved in the regulation of transcription and translation, cell division, cell wall modification, phyto-hormone metabolism and signaling transduction pathways, and metabolic pathways of carbohydrates, amino acids, and fatty acids. A scheme of abscisic acid (ABA)-biosynthesis and ABA responsive signal transduction pathway was reconstructed using these drought-induced significant proteins, showing systemic regulation at protein level to deploy the respective mechanism. Results from this study, in addition to revealing molecular responses to drought stress, provide a large number of proteins (candidate genes) that can be employed to improve switchgrass seedling growth and establishment under soil drought conditions (Data are available via ProteomeXchange with identifier PXD004675).
authors.affiliation: Department of Agricultural Sciences, Tennessee State University, 3500 John Merritt Blvd, Nashville, TN 37209, USA. zye@my.tnstate.edu.
authors.forename: Zhujia
authors.initials: Z
authors.lastname: Ye
authors.affiliation: Department of Agricultural Sciences, Tennessee State University, 3500 John Merritt Blvd, Nashville, TN 37209, USA. sangisasi@gmail.com.
authors.forename: Sasikiran
authors.initials: S
authors.lastname: Sangireddy
authors.affiliation: Department of Agricultural Sciences, Tennessee State University, 3500 John Merritt Blvd, Nashville, TN 37209, USA. iyk_oc@yahoo.com.
authors.forename: Ikenna
authors.initials: I
authors.lastname: Okekeogbu
authors.affiliation: Department of Agricultural Sciences, Tennessee State University, 3500 John Merritt Blvd, Nashville, TN 37209, USA. zsuping@tnstate.edu.
authors.forename: Suping
authors.initials: S
authors.lastname: Zhou
authors.affiliation: Department of Biological Sciences, Tennessee State University, 3500 John Merritt Blvd, Nashville, TN 37209, USA. cyu@my.tnstate.edu.
authors.forename: Chih-Li
authors.initials: CL
authors.lastname: Yu
authors.affiliation: Department of Biological Sciences, Tennessee State University, 3500 John Merritt Blvd, Nashville, TN 37209, USA. dhui@tnstate.edu.
authors.forename: Dafeng
authors.initials: D
authors.lastname: Hui
authors.affiliation: Functional & Comparative Proteomics Center, USDA-ARS, Cornell University, Ithaca, NY 14853, USA. kjh46@cornell.edu.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Howe
authors.affiliation: Functional & Comparative Proteomics Center, USDA-ARS, Cornell University, Ithaca, NY 14853, USA. tlf26@cornell.edu.
authors.forename: Tara
authors.initials: T
authors.lastname: Fish
authors.affiliation: Functional & Comparative Proteomics Center, USDA-ARS, Cornell University, Ithaca, NY 14853, USA. tt34@cornell.edu.
authors.forename: Theodore W
authors.initials: TW
authors.lastname: Thannhauser
mesh_terms: D055864:Droughts; D018506:Gene Expression Regulation, Plant; D008897:Panicum / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D020543:Proteome / Q000378:metabolism*; D040901:Proteomics; D036226:Seedlings / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics
chemical_list: D010940:Plant Proteins; D020543:Proteome
keywords: ProteoMiner; abscisic acid (ABA) signaling; functional pathways; isobaric tags for relative and absolute quantitation (iTRAQ); physiological properties; “Sandwich” plant growth system