Exogenously-applied 5-aminolevulinic acid modulates some key physiological characteristics and antioxidative defense system in spring wheat (Triticum aestivum L.) seedlings under water stress

By F. Kosar, N. Akram, M. Ashraf. 2015

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Abstract Aminolevulinic acid, one of the key precursors involved in chlorophyll biosynthesis, was applied exogenously to assess its role in improving seedling drought stress tolerance in two wheat cultivars (Shafaq-2000 and Auqab-06). Varying levels (0, 50, 100 and 150 mg L − 1 ) of 5-ALA were foliarly applied to one month old seedlings. Data showed that plant growth (shoot and root fresh and dry weights), chlorophyll a and b contents, chlorophyll a / b ratios, and leaf and root P of seedlings of both wheat cultivars decreased considerably at both drought stress regimes i.e. 80% and 60% of field capacities. In contrast, water-use efficiency (WUE) calculated as A / E and proline contents accumulated considerably under drought conditions in both wheat cultivars. However, none of the two water regimes altered sub-stomatal CO 2 concentration ( C i ), photosynthetic rate ( A ), stomatal conductance ( g s ), transpiration rate ( E ) and C i / C a ratio (Ca; ambient CO 2 concentration), glycine betaine (GB) contents, leaf and root N, Ca 2 + , and K + concentrations, activities of enzymatic antioxidants such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) and total soluble proteins in the seedlings of both wheat cultivars. 5-ALA enhanced shoot and root fresh and dry weights, chlorophyll pigments, GB contents, root K + , and N (leaf & root) in both wheat cultivars at the different water stress regimes. Of all ALA levels, 50 and 100 mg L − 1 were most effective in improving seedling growth. However, shoot and root fresh weights, shoot dry weights, chlorophyll a and b contents, A , E , g s , C i and C i / C a , and proline contents were not affected by ALA treatments. Of the wheat cultivars, cv. Shafaq-2000 showed significantly higher shoot fresh and dry weights, chlorophyll b contents, g s and C i , while cv. Uqab-06 was relatively better at proline accumulation, leaf and root P and root N concentrations. Overall, foliar-applied 5-ALA improved growth, chlorophyll a and b contents, GB, root K + , leaf and root N contents in both wheat cultivars at different water stress regimes, while all other attributes were not affected significantly.

Subfields: Molecular Biology, Plant Science

View Paper: https://www.semanticscholar.org/paper/4a0831ca914e995949911603b184a061dc8a1168