title: Label-free quantitative proteomics reveals differentially regulated proteins in the latex of sticky diseased Carica papaya L. plants.
abstract: Papaya meleira virus (PMeV) is so far the only described laticifer-infecting virus, the causal agent of papaya (Carica papaya L.) sticky disease. The effects of PMeV on the laticifers' regulatory network were addressed here through the proteomic analysis of papaya latex. Using both 1-DE- and 1D-LC-ESI-MS/MS, 160 unique papaya latex proteins were identified, representing 122 new proteins in the latex of this plant. Quantitative analysis by normalized spectral counting revealed 10 down-regulated proteins in the latex of diseased plants, 9 cysteine proteases (chymopapain) and 1 latex serine proteinase inhibitor. A repression of papaya latex proteolytic activity during PMeV infection was hypothesized. This was further confirmed by enzymatic assays that showed a reduction of cysteine-protease-associated proteolytic activity in the diseased papaya latex. These findings are discussed in the context of plant responses against pathogens and may greatly contribute to understand the roles of laticifers in plant stress responses.
authors.affiliation: Núcleo de Biotecnologia, Universidade Federal do Espírito Santo, Av. Marechal Campos 1498, Vitória, ES, Brazil.
authors.forename: Silas P
authors.initials: SP
authors.lastname: Rodrigues
authors.forename: José A
authors.initials: JA
authors.lastname: Ventura
authors.forename: Clemente
authors.initials: C
authors.lastname: Aguilar
authors.forename: Ernesto S
authors.initials: ES
authors.lastname: Nakayasu
authors.forename: HyungWon
authors.initials: H
authors.lastname: Choi
authors.forename: Tiago J P
authors.initials: TJ
authors.lastname: Sobreira
authors.forename: Lilian L
authors.initials: LL
authors.lastname: Nohara
authors.forename: Luciana S
authors.initials: LS
authors.lastname: Wermelinger
authors.forename: Igor C
authors.initials: IC
authors.lastname: Almeida
authors.forename: Russolina B
authors.initials: RB
authors.lastname: Zingali
authors.forename: Patricia M B
authors.initials: PM
authors.lastname: Fernandes
mesh_terms: D029441:Carica / Q000378:metabolism* / Q000821:virology; D010935:Plant Diseases / Q000821:virology*; D010940:Plant Proteins / Q000378:metabolism*; D010942:Plant Viruses; D040901:Proteomics
chemical_list: D010940:Plant Proteins