THE EFFECT OF ALUMINUM TREATMENT ON WHEAT ROOTS - EXPRESSION OF HEAT-SHOCK, HISTONE AND SHH GENES

The molecular mechanism by which aluminium inhibits cell division in p lant roots under acidic conditions is not understood. We have used Nor thern hybridisations to monitor changes in gene expression following A l treatment of two wheat cultivars: Warigal, an Al-sensitive variety, and Waalt, an Al-tolerant variety. Steady state transcript levels of t wo heat shock genes, hsp17 and hsp70, were not increased in roots by t he Al treatment. Levels of histone H3 and H4 transcripts were reduced by long-term exposure to inhibitory Al treatments in both wheat cultiv ars, consistent with previous reports that histone genes are expressed primarily in dividing cells. In addition, we have isolated a wheat ge ne for S-adenosyl-L-homocysteine hydrolase (SHH), and demonstrated tha t its mRNA is downregulated by long-term exposure to inhibitory levels of Al.