Deletions of chromosome 5A affect free amino acid and polyamine levels in wheat subjected to salt stress

Several genes affecting abiotic stress tolerance are located on chromosome 5A of wheat. The objective of this study was to determine the regions of the 5A chromosome, which control the salt tolerance and accumulation of free amino acids and polyamines. For this purpose, three deletion lines, 5AL-20, 5AL-8, 5AL-10, lacking increasingly large sections of chromosome 5A from the moderately salt-tolerant Triticum aestivum cv. Chinese Spring (CS) were compared. Treatment with NaCl resulted in a significantly greater decrease in fresh weight in the deletion lines than in CS. The amino acid composition was affected by both salt treatment and chromosome deletions. Among the most abundant amino acids, the relative amount of Gaba was greater in CS, while that of glutamate was greater in the deletion lines under control conditions. This difference was also observed after salt stress in the case of glutamate. Consequently, the absolute amount of glutamate was also higher in the deletion lines than in CS under both control and stress conditions. Chromosome deletions also affected the arginine, proline, valine and lysine levels. Following 100 mM NaCl treatment the putrescine and spermidine contents were lower in the deletion lines compared to the CS, while 200 mM NaCl resulted in higher putrescine content. Chromosome regions affecting amino acid and polyamine levels could be determined in the present genetic system. The distal part of the chromosome 5A may be involved in the control of salt tolerance through the regulation of Glu levels.