Nitric oxide functions as an anti-stress molecule in plants

GARCIA-MATA, C; BELIGNI, MV; LAMATTINA, L

Conferencia; First International Conference on the Biology, Biochemistry and Therapeutical Applications of Nitric Oxide.; 2000

In previous works, NO proved to alleviate deleterious effects ofoxidative stress in potato plants. In this presentation, we reportthat NO can protect different plant species from oxidative stressoriginated by three environmental conditions: water deficit, chilling and UV radiation. Detached wheat leaves treated with 100mM sodium nitroprusside (SNP), a NO releaser, retained almost30% more fresh weight than control leaves treated with H2O or 1mM NO2-/NO3- after drought and re-watering. When measured,transpiration rate in SNP-treated leaves was 21% lower than incontrol ones. When hydric stress was produced in potato leafpieces by incubation with 30% polyethylenglycol (PEG) for 5 days,NO-treated leaf pieces did not only retain 30% more water thancontrol ones, but also 20% more chlorophyll. Preliminary resultsalso showed that, at 4°C, NO-treated tomato seedlings were ableto grow, in contrast to both controls, H2O and NO2-/NO3--treated plants. Plant acclimatation to UV radiation involve thesynthesis of protective pigments [e.g. flavonoids (F) and anthocyanins (A)]. When potato leaves were exposed to UV radiationfor 30 min, NO-treated leaves showed a higher accumulation of Fand a lower cell death and necrosis than H2O-treated ones. WhenUV from 260 to 290 nm was filtered, no increase in F and A wasproduced. However, necrosis were still present in control leaves,whereas no such symptoms were observed in NO-treated ones.This suggests that NO may protect from UV radiation by at leasttwo different mechanisms. Together, these results support thatNO might play an important role in tolerance mechanisms toabiotic stresses in plants.