title: A transcriptomic network underlies microstructural and physiological responses to cadmium in Populus x canescens.
abstract: Bark tissue of Populus × canescens can hyperaccumulate cadmium, but microstructural, transcriptomic, and physiological response mechanisms are poorly understood. Histochemical assays, transmission electron microscopic observations, energy-dispersive x-ray microanalysis, and transcriptomic and physiological analyses have been performed to enhance our understanding of cadmium accumulation and detoxification in P. × canescens. Cadmium was allocated to the phloem of the bark, and subcellular cadmium compartmentalization occurred mainly in vacuoles of phloem cells. Transcripts involved in microstructural alteration, changes in nutrition and primary metabolism, and stimulation of stress responses showed significantly differential expression in the bark of P. × canescens exposed to cadmium. About 48% of the differentially regulated transcripts formed a coregulation network in which 43 hub genes played a central role both in cross talk among distinct biological processes and in coordinating the transcriptomic regulation in the bark of P. × canescens in response to cadmium. The cadmium transcriptome in the bark of P. × canescens was mirrored by physiological readouts. Cadmium accumulation led to decreased total nitrogen, phosphorus, and calcium and increased sulfur in the bark. Cadmium inhibited photosynthesis, resulting in decreased carbohydrate levels. Cadmium induced oxidative stress and antioxidants, including free proline, soluble phenolics, ascorbate, and thiol compounds. These results suggest that orchestrated microstructural, transcriptomic, and physiological regulation may sustain cadmium hyperaccumulation in P. × canescens bark and provide new insights into engineering woody plants for phytoremediation.
authors.affiliation: College of Life Sciences and State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Jiali
authors.initials: J
authors.lastname: He
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Jie
authors.initials: J
authors.lastname: Luo
authors.forename: Chaofeng
authors.initials: C
authors.lastname: Ma
authors.forename: Shaojun
authors.initials: S
authors.lastname: Li
authors.forename: Long
authors.initials: L
authors.lastname: Qu
authors.forename: Ying
authors.initials: Y
authors.lastname: Gai
authors.forename: Xiangning
authors.initials: X
authors.lastname: Jiang
authors.forename: Dennis
authors.initials: D
authors.lastname: Janz
authors.forename: Andrea
authors.initials: A
authors.lastname: Polle
authors.forename: Melvin
authors.initials: M
authors.lastname: Tyree
authors.forename: Zhi-Bin
authors.initials: ZB
authors.lastname: Luo
mesh_terms: D000222:Adaptation, Physiological; D000975:Antioxidants / Q000378:metabolism; D002104:Cadmium / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology; D050260:Carbohydrate Metabolism; D004577:Electron Probe Microanalysis; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006706:Homeostasis; D009584:Nitrogen / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D009928:Organ Specificity; D018384:Oxidative Stress; D010636:Phenols / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects; D024301:Plant Bark / Q000187:drug effects / Q000235:genetics* / Q000502:physiology / Q000648:ultrastructure; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure; D032107:Populus / Q000187:drug effects / Q000235:genetics* / Q000502:physiology / Q000648:ultrastructure; D012333:RNA, Messenger / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D013312:Stress, Physiological; D013455:Sulfur / Q000378:metabolism; D059467:Transcriptome
chemical_list: D000975:Antioxidants; D010636:Phenols; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D002104:Cadmium; D013455:Sulfur; D009584:Nitrogen