title: Transcript profiling reveals that cysteine protease inhibitors are up-regulated in tuber sprouts after extended darkness.
abstract: Potato (Solanum tuberosum L.) tubers are an excellent staple food due to its high nutritional value. When the tuber reaches physiological competence, sprouting proceeds accompanied by changes at mRNA and protein levels. Potato tubers become a source of carbon and energy until sprouts are capable of independent growth. Transcript profiling of sprouts grown under continuous light or dark conditions was performed using the TIGR 10K EST Solanaceae microarray. The profiles analyzed show a core of highly expressed transcripts that are associated to the reactivation of growth. Under light conditions, the photosynthetic machinery was fully activated; the highest up-regulation was observed for the Rubisco activase (RCA), the glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and the Photosystem II 22 kDa protein (CP22) genes, among others. On the other hand, sprouts exposed to continuous darkness elongate longer, and after extended darkness, synthesis of chloroplast components was repressed, the expression of proteases was reduced while genes encoding cysteine protease inhibitors (CPIs) and metallocarboxypeptidase inhibitors (MPIs) were strongly induced. Northern blot and RT-PCR analysis confirmed that MPI levels correlated with the length of the dark period; however, CPI expression was strong only after longer periods of darkness, suggesting a feedback loop (regulation mechanism) in response to dark-induced senescence. Prevention of cysteine protease activity in etiolated sprouts exposed to extended darkness could delay senescence until they emerge to light.
authors.affiliation: Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490 2nd piso, C1428ADN, Buenos Aires, Argentina.|Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas (IBR-CONICET) Ocampo y Esmeralda, Rosario, Argentina.
authors.forename: Carolina
authors.initials: C
authors.lastname: Grandellis
authors.affiliation: Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490 2nd piso, C1428ADN, Buenos Aires, Argentina.
authors.forename: Veronica
authors.initials: V
authors.lastname: Giammaria
authors.affiliation: Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490 2nd piso, C1428ADN, Buenos Aires, Argentina.
authors.forename: Elisa
authors.initials: E
authors.lastname: Fantino
authors.affiliation: Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490 2nd piso, C1428ADN, Buenos Aires, Argentina.|Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA), Universidad de Buenos Aires, and Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín, Buenos Aires, Argentina.|Consejo Nacional de Investigaciones Científicas y Técnicas, Av. San Martín 4453, C1417DSE, Buenos Aires, Argentina.|Instituto de Biotecnología (IB), Universidad Nacional de Hurlingham, Av. Vergara 2222, Villa Tesei, Hurlingham, B1688GEZ, Buenos Aires, Argentina.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Cerrudo
authors.affiliation: Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490 2nd piso, C1428ADN, Buenos Aires, Argentina.
authors.forename: Sandra
authors.initials: S
authors.lastname: Bachmann
authors.affiliation: Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490 2nd piso, C1428ADN, Buenos Aires, Argentina.
authors.forename: Franco
authors.initials: F
authors.lastname: Santin
authors.affiliation: Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490 2nd piso, C1428ADN, Buenos Aires, Argentina. rulloa@dna.uba.ar.|Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina. rulloa@dna.uba.ar.
authors.forename: Rita M
authors.initials: RM
authors.lastname: Ulloa
mesh_terms: D015853:Cysteine Proteinase Inhibitors; D003624:Darkness; D018506:Gene Expression Regulation, Plant; D008027:Light; D010788:Photosynthesis / Q000235:genetics*; D010940:Plant Proteins / Q000096:biosynthesis* / Q000235:genetics; D035281:Plant Tubers / Q000235:genetics / Q000254:growth & development; D036226:Seedlings / Q000235:genetics / Q000254:growth & development; D011198:Solanum tuberosum / Q000235:genetics* / Q000254:growth & development; D015533:Transcriptional Activation / Q000235:genetics
chemical_list: D015853:Cysteine Proteinase Inhibitors; D010940:Plant Proteins
keywords: Light/dark conditions; Protease inhibitors; Solanum tuberosum; TIGR 10K microarrays; Tuber sprouting