title: A transcriptional profile of metallophyte Viola baoshanensis involved in general and species-specific cadmium-defense mechanisms.
abstract: Viola baoshanensis Shu, Liu et Lan is a newly identified metallophyte, and its defensive strategies against heavy metals are still unclear. In the present study, we firstly constructed a root cDNA library of the plant subjected to 300muM Cd for 48h by using suppression subtractive hybridization (SSH), and 43 unique cDNA fragments were further isolated from the library. Sequence homology analysis showed that half of the identified genes were involved in general stress defense, such as antioxidative enzymes, protein degradation and stress signal transduction. After RT-PCR and RACE analysis, a Cd-responsive gene Vb40 was identified, which could deduce a novel cysteine-rich mini-protein. Meanwhile, five cyclotide precursor genes (VbCP1-VbCP5) were also identified. The Vb40 and the VbCP1-VbCP5 were further investigated by yeast expression analysis, and they could improve copper (Cu) tolerance in hosted yeast, indicating that these species-specific genes possibly functioned in V. baoshanensis heavy metals tolerance. Our results suggested that heavy metal tolerance in V. baoshanensis relied on both general and species-specific defense.
authors.affiliation: State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen (Zhongshan) University, Guangzhou 510006, PR China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Min
authors.initials: M
authors.lastname: Hu
authors.forename: Jin-Tian
authors.initials: JT
authors.lastname: Li
authors.forename: Jian-Ping
authors.initials: JP
authors.lastname: Guan
authors.forename: Bin
authors.initials: B
authors.lastname: Yang
authors.forename: Wen-Sheng
authors.initials: WS
authors.lastname: Shu
authors.forename: Bin
authors.initials: B
authors.lastname: Liao
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D000595:Amino Acid Sequence; D002104:Cadmium / Q000378:metabolism / Q000633:toxicity*; D003300:Copper / Q000633:toxicity; D018076:DNA, Complementary / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D017343:Genes, Plant; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D013045:Species Specificity; D014158:Transcription, Genetic / Q000187:drug effects*; D032413:Viola / Q000187:drug effects* / Q000235:genetics* / Q000276:immunology
chemical_list: D018076:DNA, Complementary; D010940:Plant Proteins; D002104:Cadmium; D003300:Copper