Abstract: Stylo (Stylosanthes guianensis) is a forage grass grown worldwide. A cultivar of stylo (‘Reyan No.2’) was shown to be able to exudate citrate and tolerate aluminum (Al). To identify Al-induced genes in stylo, we constructed a forward cDNA library for Reyan No.2 under 300 μmol·L–1 Al stress by suppression subtractive hybridization. Approximately 600 clones with inserts > 300 bp were selected for sequence analysis. In total, 504 expressed sequence tags (ESTs) were obtained: 12.1% were singletons and 61.4% presented as 2–16 copies. The highly repetitive ESTs were 10.5% for cytochrome P450-like TBP protein, with 53 copies; 8.7% for pathogen-inducible trypsin-inhibitor-like protein, with 44 copies; and 7.3% for putative senescence-associated protein, with 37 copies. BLASTX analysis revealed that the 504 ESTs could be assembled into 97 non-redundant sequences, including 46 genes with known function. Of 46 genes with known function, 30 were previously reported to be Al-responsive genes and the other 16 ESTs are novel Al-associated genes. The information provides important clues to facilitate understanding the Al detoxification mechanism in stylo at the molecular level.

Key words: Al stress, cDNA library, expressed sequence tag, Stylosanthes guianensis, suppression subtractive hybridization