title: Early changes in gene expression induced by acute UV exposure in leaves of Psychotria brachyceras, a bioactive alkaloid accumulating plant.
abstract: UV-B radiation can damage biomolecules, such as DNA, RNA, and proteins, halting essential cellular processes; this damage is partly due to ROS generation. Plant secondary metabolites may protect against UV-B. Psychotria brachyceras Müll. Arg. (Rubiaceae), a subtropical shrub, produces brachycerine, a monoterpene indole alkaloid mainly accumulated in leaf tissues, which displays antioxidant and antimutagenic activities. Exposure of P. brachyceras cuttings to UV-B radiation significantly increases leaf brachycerine concentration. It has been suggested that this alkaloid might contribute to protection against UV-B damage both through its quenching activity on ROS and as UV shield. To identify differentially expressed genes of P. brachyceras in response to UV-B and investigate a possible influence of this stimulus on putative brachycerine-related genes, suppressive subtractive hybridization was applied. Complementary DNA from UV-B-treated leaves for 24 h was used as tester, and cDNA from untreated leaves, as driver. After BLASTX alignments, 134 sequences matched plant genes. Using quantitative RT-PCR, selected genes potentially related to brachycerine showed significant increases in transcription after UV-B exposure: tryptophan decarboxylase, ACC oxidase, UDP-glucose glucosyltransferase, lipase, and serine/threonine kinase. Results suggest a possible involvement of brachycerine in acute UV-B responses and show that alkaloid accumulation seems at least partly regulated at transcriptional level.
authors.affiliation: Plant Physiology Laboratory, Graduate Program in Cell and Molecular Biology, Center for Biotechnology, Federal University of Rio Grande do Sul (UFRGS), CP 15005, Porto Alegre, RS 91501-970, Brazil.
authors.forename: Naíla Cannes
authors.initials: NC
authors.lastname: do Nascimento
authors.forename: Paloma Koprovski
authors.initials: PK
authors.lastname: Menguer
authors.forename: Raul Antonio
authors.initials: RA
authors.lastname: Sperotto
authors.forename: Márcia Rodrigues
authors.initials: MR
authors.lastname: de Almeida
authors.forename: Arthur Germano
authors.initials: AG
authors.lastname: Fett-Neto
mesh_terms: D000470:Alkaloids / Q000235:genetics / Q000378:metabolism*; D000975:Antioxidants / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000528:radiation effects; D018076:DNA, Complementary / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D007211:Indoles / Q000378:metabolism*; D039821:Monoterpenes / Q000378:metabolism*; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000528:radiation effects*; D032069:Psychotria / Q000201:enzymology / Q000254:growth & development / Q000528:radiation effects; D014158:Transcription, Genetic; D014466:Ultraviolet Rays
chemical_list: D000470:Alkaloids; D000975:Antioxidants; D018076:DNA, Complementary; D007211:Indoles; D039821:Monoterpenes; C433964:brachycerine; D004247:DNA