Influence of Proline Priming on Antioxidative Potential and Ionic Distribution and its Relationship with salt Tolerance of Wheat

Mechanisms involved in salt tolerance urge exploration and investigation of genotypic variation to assist future breeding programs. Comparative examination of ten wheat cultivars for salt tolerance and their response towards proline-seed-priming was performed. Exposure of wheat seedlings to salinity resulted in prominent reduction in root and shoot growth attributes of all cultivars. Furthermore, decrease in the chlorophyll contents was evident although this varied among cultivars. Wheat seedlings grown from proline pre-treated seeds exhibited improved photosynthetic pigments, besides this response was also cultivar and concentration dependent. Generally, salt stressed plants exhibited higher antioxidant enzyme activities. Proline priming significantly influenced antioxidant activities, however, its magnitude varied. The peroxidase activity varied among wheat cultivars that were evident from the analysis of POD activity on Native-PAGE gel. Salinity caused the accumulation of Na+ in the roots and the magnitude of Na+ translocation to the shoot was cultivar dependent. Similarly, K+ uptake and its distribution among root and shoot varied. Priming treatments affected ion distribution of Na+ and K+ but inter-cultivar variations were evident. Conclusively, all the cultivars investigated exhibited differential response to salinity and proline seed pre-treatments. However, the proline-priming mediated improvements in growth and antioxidant enzyme activities contributed to stress tolerance which partly relied on the ability of the plant to uptake sodium and its partitioning in the roots. Of the cultivars tested, Faisalabad-08 and Bhakhar-2002 were ranked as relatively salt tolerant and the cvs. AARI-10, MH-97 and Auqab-2000 as relatively salt sensitive.