The Mucilage Proteome of Maize (Zea mays L.) Primary Roots
ABSTRACT Maize (Zea mays L.) root cap cells secrete a large variety of compounds including proteins via an amorphous gel structure called mucilage into the rhizosphere. In the present study, mucilage secreted by primary roots of 3-4 day old maize seedlings was collected under axenic conditions, and the constitutively secreted proteome was analyzed. A total of 2848 distinct extracellular proteins were identified by nanoLC-MS/MS. Among those, metabolic proteins (approximately 25%) represented the largest class of annotated proteins. Comprehensive sets of proteins involved in cell wall metabolism, scavenging of reactive oxygen species, stress response, or nutrient acquisition provided detailed insights in functions required at the root-soil interface. For 85-94% of the mucilage proteins previously identified in the relatively small data sets of the dicot species pea, Arabidopsis, and rapeseed, a close homologue was identified in the mucilage proteome of the monocot model plant maize, suggesting a considerable degree of conservation between mono and dicot mucilage proteomes. Homologues of a core set of 12 maize proteins including three superoxide dismutases and four chitinases, which provide protection from fungal infections, were present in all three mucilage proteomes investigated thus far in the dicot species Arabidopsis, rapeseed, and pea and might therefore be of particular importance.
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ABSTRACT: Background Arabinogalactan proteins (AGPs) are complex proteoglycans of the cell wall found in the entire plant kingdom and in almost all plant organs. AGPs encompass a large group of heavily glycosylated cell-wall proteins which share common features, including the presence of glycan chains especially enriched in arabinose and galactose and a protein backbone particularly rich in hydroxyproline residues. However, AGPs also exhibit strong heterogeneities among their members in various plant species. AGP ubiquity in plants suggests these proteoglycans are fundamental players for plant survival and development.Annals of Botany 07/2012; 110(2):383-404. DOI:10.1093/aob/mcs143 · 3.30 Impact Factor
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ABSTRACT: Maize roots release a battery of proteins into the rhizosphere during growth and development. In the present study, mucilage secreted by primary roots of 3-4 d old maize seedlings was collected under axenic conditions, and the constitutively secreted proteins were analyzed by different methods, including two-dimensional electrophoresis--MADLI-TOF, LC-MS, and Shotgun techniques. The results showed that 200 protein spots could be observed on two-dimensional electrophoresis gel stained by silver nitrate. However, due to the low protein content for each protein spot, there was not reliable result after identification by MADLI-TOF. On the other hand, 152 and 2848 proteins were identified by LC/MS and Shotgun technique, respectively. All 152 proteins identified by LC/MS method could be found in the proteins identified by Shotgun method, and thus the results obtained by LC/MS and Shotgun method could be authenticated mutually. The results demonstrated that the Shotgun method is more sensitive than the other methods for protein identification, especially for the proteins with lower contents and complex interfering substances, such as the plant root released proteins.Guang pu xue yu guang pu fen xi = Guang pu 10/2010; 30(10):2762-6. DOI:10.3964/j.issn.1000-0593(2010)10-2762-05 · 0.27 Impact Factor
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ABSTRACT: While many studies have characterized changes to the transcriptome of plants attacked by shoot-eating insect pests, few have examined transcriptome-level effects of root pests. Maize (Zea mays) seedlings were subjected to infestation for approximately 2 weeks by the root herbivore southern corn rootworm (SCR) Diabrotica undecimpunctata howardi, and changes in transcript abundance within both roots and shoots were analyzed using a 57K element microarray. A total of 541 genes showed statistically significant changes in transcript abundance in infested roots, including genes encoding many pathogenesis-related proteins such as chitinases, proteinase inhibitors, peroxidases and β-1,3-glucanases. Several WRKY transcription factors--often associated with biotic responses--exhibited increased transcript abundance upon SCR feeding. Differentially expressed (DE) genes were also detected in shoots of infested vs control plants. Quantitative Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) was used to confirm patterns of transcript abundance for several significant DE genes using an independent experiment with a 2-6 day period of SCR infestation. Because of the well-documented roles that jasmonic acid (JA) or salicylic acid (SA) play in herbivory responses, the effect of exogenous JA or SA application on transcript abundance corresponding to the same subset of SCR-responsive genes was assessed. The response of these genes at the level of transcript abundance to SA and JA differed between roots and shoots and also differed among the genes that were examined. These data suggested that SA- and JA-dependent and independent signals contributed to the transcriptome-level changes in maize roots and shoots in response to SCR infestation.Physiologia Plantarum 12/2011; 144(4):303-19. DOI:10.1111/j.1399-3054.2011.01557.x · 3.26 Impact Factor