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 plant roots under acidic conditions is not understood. We have used Northern hybridisations to monitor changes in gene expression following Al treatment of two wheat cultivars: Warigal, an Al-sensitive variety, and Waalt, an Al-tolerant variety. Steady state transcript levels of two heat shock genes, hsp17 and hsp70, were not increased in roots by the Al treatment. Levels of histone H3 and H4 transcripts were reduced by long-term exposure to inhibitory Al treatments in both wheat cultivars, consistent with previous reports that histone genes are expressed primarily in dividing cells. In addition, we have isolated a wheat gene for S-adenosyl-L-homocysteine hydrolase (SHH), and demonstrated that its mRNA is downregulated by long-term exposure to inhibitory levels of Al.