Effect of foliar application of putrescine on free proline, soluble and insoluble carbohydrates in spring safflower (Carthamus tinctorius L.) under water deficit

Water deficit has negative effect on plant growth and development. Polyamines are growth regulator in plants and increased their tolerance to drought. In this research the effect of putrescine foliar application (40 and 60 μM) on leaf proline, shoot and root soluble and insoluble sugars contents in safflower plants under different levels of water supply (100% and 40% field capacity) was studied as factorial arrangement based on complete randomized block design with three replications. Interaction of water deficit and putrescine for proline content and soluble sugars was significant. Proline content (leaf) and soluble sugars (shoot, root) significantly decreased with 40 and 60 μM putrescine under water deficit. Putrescine as osmolyte and recactive oxygen species scavenger reduced production and accumulation of compatible osmolytes. In nonstressed plants, effect of putrescine on proline and soluble sugars was different related to concentration. Insoluble sugars increased with both concentration of putrescine in shoot and decreased in root. Chlorophyll content maintenance in stressed plants increases drought tolerance. Reducing proline in stressed plants treated by putrescine can be related to enhancing chlorophyll content. Since proline and chlorophyll were synthesized from the same precursor (glutamate). Also increasing antioxidant enzymes activities in these plants can improve plant resistance. Decreasing soluble sugars with putrescine might be attributed to better water status of polyamine treated plants. Putrescine via increasing chlorophyll, relative water contents and antioxidant enzymes activities can enhance safflower resistance to drought without increasing osmolytes biosynthesis.

Keywords:

Drought stress , Putrescine , Safflower , Osmolytes