Comparative Analysis of Physiological and Biochemical Responses to Salt Stress Reveals Important Mechanisms of Salt Tolerance in Wheat

Salinity tolerance varies among wheat (<i>Triticum aestivum</i>) tissues and cultivars. This study investigated the impact of salt stress on two Saudi wheat cultivars, Qiadh and Najran. Growth parameters (fresh weight, dry weight and plant length), biochemical responses (proline, soluble sugars, starch and organic acids contents) and antioxidants (phenolics content), as well as gene responses, were assessed in the control and salt (NaCl)-treated plants. A distinctive variation was observed between the two cultivars. Najran was the most tolerant to salt stress. Salt stress caused a dramatic decline in growth parameters in both cultivars; however, Qiadh exhibited the highest reduction in growth and yield. Differential increase in metabolite content occurred in the two cultivars under salinity stress, with levels varying between cultivars and roots and shoots. Transcripts for genes involved in the production of proline, sugars, starch and phenolics increased in shoots and roots, to higher levels in Qiadh compared to Najran. Interestingly, transcript levels for genes involved in sugar and starch synthesis declined in Najran roots. The obtained results confirm that different wheat cultivars employ varying mechanisms to alleviate the harmful effects of salt stress. The salt-tolerant Najran cultivar might constitute a genetic source for breeding enhanced salt tolerance in other wheat cultivars.