An S-adenosyl Methionine Synthetase (SAMS) Gene from Andropogon virginicus L. Confers Aluminum Stress Tolerance and Facilitates Epigenetic Gene Regulation in Arabidopsis thaliana

Abstract

Candidate clones which conferred Al tolerance to yeast transformants (TFs) were obtained from a cDNA library derived from a highly Al-tolerant poaceae, <i>Andropogon virginicus</i> L. One such clone, AL3A-4, encoded an S-adenosyl methionine synthetase (SAMS) gene. A full-length cDNA was obtained by 5'-RACE, designated <i>AvSAMS1</i>, and introduced into <i>Arabidopsis thaliana</i> to investigate its biological functions under Al stress. Two TF plant lines both showed higher tolerance than the Col-0 ecotype (non-TF) not only for Al stress, but also for Cu, Pb, Zn and diamide stresses, suggesting the <i>AvSAMS1</i> was a multiple tolerance gene. More than 40 of <i>A. thaliana</i> Al response-genes (Al induced genes and Al repressed genes) were selected from microarray results and then used for investigations of DNA or histone methylation status under Al stress in Col-0 and the <i>AvSAMS1</i> TF line. The results indicated that Al stress caused alterations of methylation status in both DNA and histone H3 (H3K4me3 and H3K9me3) and that these alterations were different between the <i>AvSAMS1</i> TF and Col-0, suggesting the differences were <i>AvSAMS1</i>-gene dependent. These results suggested the existence of <i>AvSAMS1</i>-related epigenetic gene-regulation under Al stress.