Unknown,Transcriptomics,Genomics,Proteomics

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Differential transcript accumulation in seedling and mature shoots identifies components contributing to corn earworm resistance

ABSTRACT: As maize seedlings germinate into the soil, they encounter an environment teeming with insects seeking rich sources of nutrition. Maize presumably has developed a number of molecular mechanisms to ensure survival at the beginning of its life cycle. Bioassays indicated maize seedlings were more toxic to caterpillars than shoots from 3 or 4 leafed plants. Microarray technology was utilized to document the expression of a number of genes with potential defensive functions in seedling tissue. In addition to elevated levels of the genes involved in the biosynthesis of DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one), an anti-insect resistance molecule, other highly expressed genes in the seedling encode the following putative proteins: defensin, hydroxyproline and proline-rich protein, thaumatin-like protein, lipase, cystatin, protease inhibitor, and a variety of proteases. Changes in the levels of gene expression by the microarray technology were well correlated to results using quantitative RT-PCR. The potential resistance genes identified occurred mainly on chromosomes 1 and 5 in the B73 genome. Analysis of promoters of four DIMBOA biosynthetic genes determined that a Dof transcription factor, two of which were differentially expressed in three vegetative stages, is possibly involved in regulation of the DIMBOA biosynthetic pathway. The results indicate that maize employs a wide variety of potential resistance mechanisms in seedling tissue to resist a possible insect attack. Three different Zea mays plant (B73) life stages were sampled: a) seedlings, which had grown just above the soil line, which also served as reference tissue (reference tissue was always labeled Cy5 and consisted of leaf shoots pooled from 12 plants); b) leaf shoots from plants with four leaves; and c) leaf shoots from plants with six leaves. There were 3 samples (biological replications) of each treatment (6 plants per sample) and the samples were labeled Cy3 and which were combined with a reference chip for a total of 9 chips: (3 biological replicates of seedling, 4 leaf stage and 6 leaf stage).

ORGANISM(S): Zea mays

SUBMITTER: Richard Musser

PROVIDER: E-GEOD-27709 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Comparative transcription profiling analyses of maize reveals candidate defensive genes for seedling resistance against corn earworm.

Johnson Eric T ET Dowd Patrick F PF Liu Z Lewis ZL Musser Richard O RO

Molecular genetics and genomics : MGG 20110510 6

As maize seedlings germinate into the soil, they encounter an environment teeming with insects seeking rich sources of nutrition. Maize presumably has developed a number of molecular mechanisms to ensure survival at the beginning of its life cycle. Comparative transcription analysis using microarrays was utilized to document the expression of a number of genes with potential defensive functions in seedling tissue. In addition to elevated levels of the genes involved in the biosynthesis of DIMBOA ...[more]

PMID: 21556895

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Project description:The metabolic response of maize source leaves to low nitrogen supply was analyzed in maize seedlings by parallel measurements of transcriptome and metabolome profiling. Inbred lines A188 and B73 were cultivated under controlled growth chamber conditions and supplied with either sufficient (15mM) or limiting (0.15mM) nitrate supply. Leaf lamina material was harvested at day 20 and day 30 after germination with the fifth and sixth leaf representing the main source leaf respectively. Four replicates were collecetd from individual plants for each combination of genotype, growth stage and nitrogen treatment. The leaf material was frozen, homogenised and aliquoted for transcriptome and metabolome analysis. The molecular data was further supplemented by phenotypic characterisation of the maize seedlings under investigation. Limited availability of nitrogen caused strong shifts in the metabolite profile of leaves. The transcriptome was less affected by the nitrogen stress but showed strong genotype and age dependent patterns. Nitrogen starvation initiated the selective down-regulation of processes involved in nitrate reduction and amino acid assimilation; ammonium assimilation related transcripts on the other hand were not influenced. Carbon assimilation related transcripts were characterized by high transcriptional coordination and general down-regulation under low nitrogen conditions. Nitrogen deprivation caused a slight accumulation of starch, but also directed increased amounts of carbohydrates into the cell wall and secondary metabolites. The decrease in N availability also resulted in accumulation of phosphate and by strong down-regulation of genes usually involved in phosphate starvation response, underlining the great importance of phosphate homeostasis control under stress conditions. Maize inbred lines A188 and B73 were cultivated in pots containing nutrient poor peat soil under the controlled conditions of a growth chamber. The plants were fertilized with modified Hoagland solutions containing either 15mM (high N) or 0.15mM nitrate (low N). Source leaf lamina were harvested at day 20 and day 30 after start of germination for parallel analysis of transcriptome and metabolome profiles. The molecular data is further supplemented by phenotypic characterization of the maize seedlings under investigation.

Dataset Information

Differential transcript accumulation in seedling and mature shoots identifies components contributing to corn earworm resistance

Publications

Comparative transcription profiling analyses of maize reveals candidate defensive genes for seedling resistance against corn earworm.

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