geNorm analysis of average expression stability values and ranking of ten candidate reference genes based on pairwise comparison.

<p>Genes on the x-axis in order of increasing stability (y-axis M value) for (A) all samples, (B) drought-treated samples, (C) boron-treated samples, (D) fungal-infected samples, (E) salt-treated samples and (F) nitrate-treated samples. Under individual treatment condition, reference genes’ expression stability was obtained comparing to the untreated (control) condition.