Table 1.
Kernel aflatoxin levels in the four maize inbred lines used for the DNA microarray analysis.
Figure 1.
Biplots showing results of the principal component analysis (PCA) on log2 expression ratios (I/U) of 13,107 expressed genes.
The distribution of the gene expression values shows evident trends represented by the vectors associated with resistant and susceptible maize inbred lines. Genes expressed toward the resistance trait were located close to the vectors for Mp313E and Mp04∶86. Genes contributing to susceptibility were located close to the vectors for Va35 and B73. 1A. Biplot of principal component analysis (PCA) on 13,107 expressed gene probes. 1B. Biplot of principal component analysis (PCA) on a subset of 500 expressed gene probes. (The arrows represent vectors. The direction and length represent the larger variance of the expression values).
Table 2.
Primer sequences of candidate genes and the house keeping gene GAPDH in qRT-PCR study.
Figure 2.
Bar-graph showing the comparison of the grand mean relative expression levels for each candidate gene in Mp313E and Va35 lines over all time points.
Thirty-one of the 50 genes were found to be significantly differentially expressed (P<0.05) by a paired t-test between the Mp313E and Va35 samples. The error bars represent 95% CI values.
Table 3.
Genes differentially expressed in the resistant maize inbred line Mp313E and the susceptible maize inbred line Va35 verified by qRT-PCR method.
Figure 3.
Plot showing the grouping of Mp313E and Va35 samples in the qRT-PCR study by principal component analysis.
Notice the Mp313E and Va35 samples were grouped into two distinct groups. It indicated the criteria used for candidate gene selection from the microarray data were effective in reflecting host plant specific responses to the fungal infection.
Figure 4.
Plot of PCA analysis on the 50 candidate genes differentially expressed in Mp313E versus Va35.
Genes highly expressed in Mp313E were presented in the area with positive values of y axis coordinates, whereas genes located in the area with negative values of y axis coordinates were those expressed more inVa35.
Figure 5.
2D plot showing gene expression levels over a period of 21 days after the fungal inoculation.
These genes are highly expressed in Mp313E than in Va35.
Figure 6.
2D plot showing gene expression levels over a period of 21 days after the fungal inoculation.
These genes are highly expressed in Va35 than in Mp313E.
Figure 7.
Chromosome bin map showing the positions of the significant genes and the previously identified QTL regions.
Eight genes were mapped within or close to the seven most significant QTL regions. The top highly expressed gene in Va35, AI664980 (Chr1, bin1.06), is located in the most significant chromosome 1 QTL region (Chr 1, bin 1.5–1.9) identified from the Va35 x Mp313E population. The top highly expressed gene in Mp313E, TC231674 (Chr 5, bin 5.05), is mapped to the chromosome 5 QTL region (Chr 5, bin 5.05) identified from B73 x Mp313E population.