Studying the Expression Pattern of PMP3 and Dehydrin Genes in AS5305 and 9CSA3 Oily Sunflower Lines under Salt Stress

In this study, the tolerance of sunflower lines was investigated to salinity stress at the molecular level by studying the expression of PMP3 and Dehydrin genes in two oilseed sunflower lines [AS5305 (tolerant) and 9CSA3 (susceptible)] under different levels of salinity; 2, 5, 8, 11 and 14 dS/m (equivalent to 20, 50, 80, 110 and 140 mM NaCl) using real time PCR technique. Sampling of sunflower leaves was performed in 8-leaf stage at five time intervals; 0, 6, 12, 24 and 48 hours after stress application. The results of the study showed that in the early stages of salinity stress, the highest expression of PMP3 gene in AS5305 line was observed at salinity level lower than that for 9CSA3 line (8 vs 11 ds/m). In more advanced stages of salinity stress (24 hours after stress application), the increased expression level of PMP3 gene in AS5305 line was observed at low salt intensity (2 and 5 dS/m) whereas in the case of 9CSA3 line it was observed at more severe salt intensity (5 and 8 dS/m). In relation to Dehydrin gene, an increase in the expression level at the early stages was observed only in 9CSA3 line. In the advanced stages at more sever salinity stress (14 ds/m), the increased expression level of Dehydrin gene was 1.5 times higher in AS5305 line than that in 9CSA3 line. In contrast, at low salt intensity (5 and 8 dS/m), the increased expression level of Dehydrin gene was greater in 9CSA3 line than that in AS5305 line. Therefore, the higher concentrations of salinity stress in advanced and more advanced stages of salinity stress may induce morely the expression level of Dehydrin gene in AS5305 line than that in 9CSA3 line. Totaly the results show that the pattern of expression of studied genes in two investigated lines is different, which is due to their different response to salinity stress. This suggests that these genes are potentially involved in tolerance to salinity stress, which can be useful in breeding and development of plants potentially resistance to stress.