title: A joint transcriptomic, proteomic and metabolic analysis of maize endosperm development and starch filling.
abstract: The maize endosperm transcriptome was investigated through cDNA libraries developed at three characteristic stages: (i) lag phase [10 days after pollination (DAP)]; (ii) beginning of storage (14 DAP); and (iii) maximum starch accumulation rate (21 DAP). Expressed sequence tags for 711, 757 and 384 relevant clones, respectively, were obtained and checked manually. The proportion of sequences with no clear function decreased from 35% to 20%, and a large increase in storage protein sequences (i.e. 5% to 38%) was observed from stages (i) to (iii). The remaining major categories included metabolism (11%-13%), transcription-RNA processing-protein synthesis (13%-20%), protein destination (5%-9%), cellular communication (3%-9%) and cell rescue-defence (4%). Good agreement was generally found between category rank in the 10-DAP transcriptome and the recently reported 14-DAP proteome, except that kinases and proteins for RNA processing were not detected in the latter. In the metabolism category, the respiratory pathway transcripts represented the largest proportion (25%-37%), and showed a shift in favour of glycolysis at 21 DAP. At this stage, amino acid metabolism increased to 17%, whereas starch metabolism surprisingly decreased to 7%. A second experiment focused on carbohydrate metabolism by comparing gene expression at three levels (transcripts, proteins and enzyme activities) in relation to substrate or product from 10 to 40 DAP. Here, two distinct patterns were observed: invertases and hexoses were predominant at the beginning, whereas enzyme patterns in the starch pathway, at the three levels, anticipated and paralleled starch accumulation, suggesting that, in most cases, transcriptional control is responsible for the regulation of starch biosynthesis.
authors: Université Paris-Sud, Institut de Biotechnologie des Plantes, Bât. 630, F-91405 Orsay, France. jean-louis.prioul@u-psud.fr
authors: Jean Louis
authors: JL
authors: Prioul
authors: Valérie
authors: V
authors: Méchin
authors: Philippe
authors: P
authors: Lessard
authors: Claudine
authors: C
authors: Thévenot
authors: Mike
authors: M
authors: Grimmer
authors: Sophie
authors: S
authors: Chateau-Joubert
authors: Steve
authors: S
authors: Coates
authors: Hans
authors: H
authors: Hartings
authors: Monica
authors: M
authors: Kloiber-Maitz
authors: Alain
authors: A
authors: Murigneux
authors: Xavier
authors: X
authors: Sarda
authors: Catherine
authors: C
authors: Damerval
authors: Keith J
authors: KJ
authors: Edwards
mesh_terms: D050260:Carbohydrate Metabolism; D018076:DNA, Complementary / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling; D005838:Genotype; D006026:Glycoside Hydrolases / Q000235:genetics; D020543:Proteome; D018749:RNA, Plant / Q000235:genetics; D013213:Starch / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D003313:Zea mays / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D018744:DNA, Plant; D020543:Proteome; D018749:RNA, Plant; D013213:Starch; D006026:Glycoside Hydrolases; C100181:pullulanase