Effects Of Exogenous No On The Physiological Mechanism In Embryo Germination Of Sorbus Pohuashanensis

This study, mature zygotic embryo of Sorbus pohuashanensis were used to study effects of SNP, PTIO, cPTIO, ABA, ethephon and NBD on the ethylene release of embryo endogenous, reactive oxygen species and antioxidant enzyme activity in the process of embryo germination of S. pohuashanensis were analyzed by indoor petri dish germination method. The findings provided a scientific basis for the effect and mechanism of action of NO on the breaking of embryo dormancy and embryo germination of S. pohuashanensis. The results were as follows. Embryos of S. pohuashanensis were dealt with SNP, PTIO and cPTIO. According to the observation of germination, the results indicated that the treatment of0～5mmol·L-1SNP could promote the germination of S. pohuashanensis, and the germination rate increased first then decreased with the increase of SNP concentration. The optimum effect of embryo germination generated when the concentration of SNP was2mmol·L-1. The germination rate of embryos, average germination rate, germination index and germination potential with kinds of SNP treatment were all higher than those of the control group. The germination of embryos was inhibited significantly because of NO scavenger. SNP could weak the inhibiting effect of PTIO on embryo germination.Embryos of S. pohuashanensis were dealt with SNP, ABA and Ethephon. According to the observation of germination, it indicated that the germination of embryos was inhibited when the concentration of ABA was3.0μmol·L-1. The germination rate of embryos, average germination rate, germination index and germinative energy were all enhanced with the combined treatment of2mmol·L-1SNP and ABA. Ethephon could promote the embryo germination of S. pohuashanensis. The treatment dealt with NBD inhibited the germination significantly compared with the control group. There was no obvious difference between the indicators of combined treatment with SNP and NBD and the treatment with NBD. It demonstrated that SNP could not change the inhibiting effect of NBD on germination of embryos.The ethylene release of embryo endogenous of S. pohuashanensis was measured by gas chromatographic method. The results showed that the treatment of SNP increased the ethylene release observably. The ethylene release was inhibited significantly by NO scavenger. The inhibiting effect of PTIO on ethylene release of embryo germination was decreased by SNP. The ethylene release with different treatment method in descending order was SNP, SNP+cPTIO (or SNP+PTIO) and cPTIO (or PTIO).The treatment of SNP on the embryo of S. pohuashanensis had obvious effect on accumulation of reactive oxygen species of embryo. Because of SNP, the MDA of embryo and seedling, superoxide anion content was decreased, but the H2O2content was increased. And the treatment of PTIO had an opposite effect. The effect of PTIO on reactive oxygen species was decreased by SNP.According to the measurement of soluble protein content, SOD, CAT, POD, GSH-PX of embryo of S. pohuashanensis, the results indicated that the content of soluble protein and GSH could be increased by SNP. And the activity of SOD, CAT and GSH-PX was enhanced. But PTIO showed an opposite effect. The combined treatment of SNP and PTIO on embryo of S. pohuashanensis decreased the effect of PTIO significantly.In conclusion, optimal concentration of SNP could promote the embryo germination of S. pohuashanensis. The inhibiting effect of NO scavenger on embryo germination of S. pohuashanensis could be reversed by SNP pretreatment. SNP might remit the inhibiting effect of ABA on embryo germination, but could not decrease the inhibiting effect of NBD on embryo. Exogenous NO not only may promote the ethylene release of embryo of S. pohuashanensis, but also have effect on reactive oxygen metabolism and autioxidant enzyme activity of embryo.