Nitric Oxide Involvement in Bermudagrass Response to Salt Stress

Bermudagrass [Cynodon dactylon (L.) Pers.] is a warm- season turfgrass that has the potential to improve saline and alkaline soils. However, its utilization is severely limited by high salinity. Therefore, it is urgent to enhance its tolerance to salt stress. Previous studies have proved that nitric oxide (NO) plays a vital role in various biological processes. However, the role ofNOin bermudagrass response to salt is unknown. Our objective here was to investigate whether and how NO contributes to the protection of bermudagrass against salt stress in bermudagrass. In this study, sodium nitroprusside (SNP) served as the NO donor, while 2- phenyl- 4,4,5,5- tetramentylimidazoline- l- oxyl- 3- xide (PTIO) plus NG- nitro- L- arginine methyl ester (L- NAME) acted as the NO inhibitor. The treatment of bermudagrass with 400 mM salt solution occurred under different regimes: control, SNP, PTIO D L- NAME (PL). The results showed that 400 mM salinity caused significant toxicity to bermudagrass. However, SNP alleviated damage effect on plant growth and ionic balance as indicated by higher water content, chlorophyll content, higher chlorophyll a fluorescence (OJIP) curves and K+: Na+, Mg2+: Na+, and Ca2+: Na+ ratios. Also, lower levels of electrolyte leakage, malonaldehyde, H2O2, superoxide dismutase, peroxidase, and ascorbate peroxidase activities suggested that NO reduced the membrane injury and lipid peroxidation under salt treatment, while PL regime showed severe damage. In summary, our results suggest that NO has some beneficial effects on the maintenance of cell membrane stability, alleviation of oxidative damage and maintenance of ion homeostasis and plant photosythesis when bermudagrass is exposed to high salinity condition.