title: Expression profile of maize (Zea mays L.) embryonic axes during germination: translational regulation of ribosomal protein mRNAs.
abstract: Seed germination is a critical developmental period for plant propagation. Information regarding gene expression within this important period is relevant for understanding the main biochemical processes required for successful germination, particularly in maize, one of the most important cereals in the world. The present research focuses on the global microarray analysis of differential gene expression between quiescent and germinated maize embryo stages. This analysis revealed that a large number of mRNAs stored in the quiescent embryonic axes (QEAs) were differentially regulated during germination in the 24 h germinated embryonic axes (GEAs). These genes belong to 14 different functional categories and most of them correspond to metabolic processes, followed by transport, transcription and translation. Interestingly, the expression of mRNAs encoding ribosomal proteins [(r)-proteins], required for new ribosome formation during this fast-growing period, remains mostly unchanged throughout the germination process, suggesting that these genes are not regulated at the transcriptional level during this developmental period. To investigate this issue further, comparative microarray analyses on polysomal mRNAs from growth-stimulated and non-stimulated GEAs were performed. The results revealed that (r)-protein mRNAs accumulate to high levels in polysomes of the growth-stimulated tissues, indicating a translational control mechanism to account for the rapid (r)-protein synthesis observed within this period. Bioinformatic analysis of (r)-protein mRNAs showed that 5' TOP (tract of pyrimidines)-like sequences are present only in the 5'-untranslated region set of up-regulated (r)-protein mRNAs. This overall approach to the germination process allows an in-depth view of molecular changes, enabling a broader understanding of the regulatory mechanisms that occur during this process.
authors: Biochemistry Department, Faculty of Chemistry, Universidad Nacional Autónoma de Mexico (UNAM), Ciudad Universitaria, 04510 Mexico, D.F. México.
authors: Sara
authors: S
authors: Jiménez-López
authors: Eder
authors: E
authors: Mancera-Martínez
authors: Alberto
authors: A
authors: Donayre-Torres
authors: Claudia
authors: C
authors: Rangel
authors: Laura
authors: L
authors: Uribe
authors: Santiago
authors: S
authors: March
authors: Gerardo
authors: G
authors: Jiménez-Sánchez
authors: Estela
authors: E
authors: Sánchez de Jiménez
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D001483:Base Sequence; D019295:Computational Biology; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D030541:Databases, Genetic; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018745:Genome, Plant / Q000235:genetics; D018525:Germination / Q000187:drug effects / Q000235:genetics*; D007328:Insulin / Q000494:pharmacology; D059372:Nucleotide Motifs; D020411:Oligonucleotide Array Sequence Analysis; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012015:Reference Standards; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012269:Ribosomal Proteins / Q000235:genetics* / Q000378:metabolism; D012639:Seeds / Q000187:drug effects / Q000235:genetics*; D013997:Time Factors; D003313:Zea mays / Q000187:drug effects / Q000196:embryology* / Q000235:genetics*
chemical_list: D020121:5' Untranslated Regions; D007328:Insulin; D010940:Plant Proteins; D012333:RNA, Messenger; D012269:Ribosomal Proteins