Transcriptional analysis between two wheat near-isogenic lines contrasting in aluminum tolerance under aluminum stress

To understand the mechanisms of aluminum (Al) tolerance in wheat (Triticum aestivum L.), suppression subtractive hybridization (SSH) libraries were constructed from Al-stressed roots of two near-isogenic lines (NILs). A total of 1,065 putative genes from the SSH libraries was printed in a cDNA array. Relative expression levels of those genes were compared between two NILs at seven time points of Al stress from 15 min to 7 days. Fifty-seven genes were differentially expressed for at least one time point of Al treatment. Among them, 28 genes including genes for aluminum-activated malate transporter-1, ent-kaure-noic acid oxidase-1, beta-glucosidase, lectin, histidine kinase, and phospoenolpyruvate carboxylase showed more abundant transcripts in Chisholm-T and therefore may facilitate Al tolerance. In addition, a set of genes related to senescence and starvation of nitrogen, iron, and sulfur, such as copper chaperone homolog, nitrogen regulatory gene-2, yellow stripe-1, and methylthioribose kinase, was highly expressed in Chisholm-S under Al stress. The results suggest that Al tolerance may be co-regulated by multiple genes with diverse functions, and those genes abundantly expressed in Chisholm-T may play important roles in enhancing Al tolerance. The down-regulated genes in Chisholm-S may repress root growth and restrict uptake of essential nutrient elements, and lead to root senescence.