Proline Accumulation and Related Genes in Wheat Leav es under Salinity Stress

Abstract

This study was carried out to evaluate the effects of salinity stress (16 dS m -1 ) on proline accumulation and expression pattern of three genes involved in the proline synthesis (P5CS, P5CR) and degradation (PDH) in the fourth an d the flag leaves. The experimental treatments consisted of two levels of salinity stre ss including 1.6 (control) and 16 dS m -1 and three wheat cultivars, namely, Hirmand and Cham ran (as tolerant cultivars) and Atrak (as sensitive). These were arranged as factor ial based on a Completely Randomized Design with three replications. There was an increa se in Na + concentration and decrease in K + concentration in salinity stress compared to the c ontrol condition in the fourth and the flag leaves of all cultivars. However, the tole rant cultivars showed lower level of Na + concentration and higher level of K + concentration and K + / Na + ratio. Seemingly, the increase in proline accumulation was due to P5CS, P 5CR up-regulation and PDH down- regulation. On the other hand, the higher proline degradation i n the fourth leaf of the tolerant cultivars was probably due to the provisio n of a source for energy or nitrogen, which helped to enhance the yield of these cultivar s under salinity stress. Keywords : Proline, Salinity, Wheat, P5CS, P5CR, PDH.