Control Of Exogenous NO And H₂O₂on Dry Rot Of Potato Tuber And Its Possible Mechanism Involved

Potato is an important economic crop in Gansu province and its acreage andproduction was increased year by year, but the loss of postharvest diseases was severe,especially the dry rot caused by Fusarium sulphureum, therefore, there is a need fordevelopment of safety strategies to control dry rot of potato tubers. Nitric Oxide andHydrogen Peroxide are two important signaling molecule and played essential roles ininduce resistance of potato. Potato tubers (Solanum buberosum cv. longshu no.3)were treated with NO and H2O2then research its inhibition activity, exogenous NOand H2O2treatment on potato tuber disease resistance, the generation of endogenousNO and H2O2, the induced effect and possible mechanism of it in chitosan treatmenton potato tuber resistance, preliminary discussion its synergistic effect in diseasecontrol, the produce scheduling of endogenous NO and H2O2, and related signalingpathway.1Exogenous SNP and H2O2could significantly inhibited the growth of F.sulphureum and the inhibitory effect exhibited concentration and time dependence.After treated with1g/100mL SNP, the percentage of spore germination was73%, themycelial diameter was82.4%of the untreated control. The inhibitory effect of H2O2is better, after treatment the spore germination and mycelial growth were almostcompletely exhibited. By scanning electron micrographs (SEM) and transmissionelectron microscopy (TEM) observation, the hyphal morphology and ultrastructure ofF. sulphureum are damaged after treated with exogenous SNP and H2O2. The resultsin vivo further proved the inhibitory effect of NO and H2O2.2After treated with0.5g/100mL SNP, lesion diameter in potato slices and potatotubers were79%and75%of the untreated control, respectively. And after treatedwith0.25%（v/v）H2O2, the lesion diameter were72.4%and72%of the untreatedcontrol, indicated that the induced effects of H2O2was better. Compared with control,the the rate of superoxide anion production, the accumulation of hydrogen peroxide,and the activities of NADPH oxidase, SOD, CAT, POD, PPO were significantlyincreased after treated with exogenous SNP and H2O2. Simultaneously, endogenousNO and H2O2level were rapid increased in a short time, the induced effects of H2O2was better.3Combined treated in chitosan with SNP or H2O2, lesion diameter in potatoslices and potato tubers were91.5%,92.8%and84.9%,87.2%of the single chitosan treatment. These induced effect could reversed by the cPTIO and CAT. In addition,endogenous NO and H2O2level in potato were significantly increased.4The lesion diameter in potato slices and potato tubers were79.7%and70.7%of the control after combined treated with SNP and H2O2. Simultaneously, reactiveoxygen metabolism related enzyme activity and products in potato were increased.In conclusion, exogenous SNP and H2O2had well inhibition-activity to F.sulphureum, could induce the potato disease resistance and play crucial role in inducethe potato disease resistance of chitosan, in addition, they had synergistic effect ininduce the potato disease resistance, indicates that NO and H2O2plays an importantrole in the induced resistance to potato.