Transcriptional and metabolic analysis of senescence induced by preventing pollination in maize.
Transcriptional and metabolic changes were evaluated during senescence induced by preventing pollination in the B73 genotype of maize (Zea mays). Accumulation of free glucose and starch and loss of chlorophyll in leaf was manifested early at 12 d after anthesis (DAA), while global transcriptional and phenotypic changes were evident only at 24 DAA. Internodes exhibited major transcriptomic changes only at 30 DAA. Overlaying expression data onto metabolic pathways revealed involvement of many novel pathways, including those involved in cell wall biosynthesis. To investigate the overlap between induced and natural senescence, transcriptional data from induced senescence in maize was compared with that reported for Arabidopsis (Arabidopsis thaliana) undergoing natural and sugar-induced senescence. Notable similarities with natural senescence in Arabidopsis included up-regulation of senescence-associated genes (SAGs), ethylene and jasmonic acid biosynthetic genes, APETALA2, ethylene-responsive element binding protein, and no apical meristem transcription factors. However, differences from natural senescence were highlighted by unaltered expression of a subset of the SAGs, and cytokinin, abscisic acid, and salicylic acid biosynthesis genes. Key genes up-regulated during sugar-induced senescence in Arabidopsis, including a cysteine protease (SAG12) and three flavonoid biosynthesis genes (PRODUCTION OF ANTHOCYANIN PIGMENT1 (PAP1), PAP2, and LEUCOANTHOCYANIDIN DIOXYGENASE), were also induced, suggesting similarities in senescence induced by pollination prevention and sugar application. Coexpression analysis revealed networks involving known senescence-related genes and novel candidates; 82 of these were shared between leaf and internode networks, highlighting similarities in induced senescence in these tissues. Insights from this study will be valuable in systems biology of senescence in maize and other grasses.
Department of Energy Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, Wisconsin 53706, USA.
Rajandeep S
RS
Sekhon
Kevin L
KL
Childs
Nicholas
N
Santoro
Cliff E
CE
Foster
C Robin
CR
Buell
Natalia
N
de Leon
Shawn M
SM
Kaeppler
D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D050260:Carbohydrate Metabolism / Q000187:drug effects / Q000235:genetics; D002241:Carbohydrates / Q000096:biosynthesis / Q000494:pharmacology; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D053263:Gene Regulatory Networks / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics; D005838:Genotype; D053858:Metabolic Networks and Pathways / Q000187:drug effects / Q000235:genetics; D055442:Metabolome / Q000187:drug effects / Q000235:genetics*; D055432:Metabolomics; D000073718:Pancreatitis-Associated Proteins; D010641:Phenotype; D010788:Photosynthesis / Q000235:genetics; D010937:Plant Growth Regulators / Q000378:metabolism; D054817:Pollination / Q000235:genetics*; D013045:Species Specificity; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects; D059467:Transcriptome / Q000187:drug effects / Q000235:genetics*; D003313:Zea mays / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*
D002241:Carbohydrates; D000073718:Pancreatitis-Associated Proteins; D010937:Plant Growth Regulators; C000612141:REG3A protein, human