Study On The Physiological And Biochemical Indexes Of Soybean Plants Infected By Heterodera Sojae

Heterodera sojae was first discovered and reported in Korea in 2016.In 2016,our laboratory also found this nematode in Jiangxi province and 42 soybean cultivar resistance to H.sojae was identified.However,other studies on H.soiae have not been reported.In this paper,soybean and H.soiae were used as materials to investigate the changes of physiological and biochemical indexes in the roots of soybeans infected by H.sojae.The development and hatching of H.sojae in different resistant soybean roots were analyzed,and this nematode on host soybean growth were also analyzed.The main results of this paper are as follows:The physiological and biochemical indexes of soybean infected by H.sojae showed:the most effective indexe for early identification of soybean against H.sojae was MDA,followed by POD activity,and again soluble protein,while CAT,SOD,PAL and PPO activities are not suitable for judging whether early soybeans are resistant to H.sojae.In0-3 days after inoculation with the H.soiae,the content of malondialdehyde（MDA）in susceptible cultivar was significantly increased,while the control group of susceptible cultivar,the inoculation group and control group of resistant cultivar.The activity of peroxidase（POD）in the group of resistant cultivar was rapidly increased,and the activity of the control group of resistant cultivar was almost unchanged,however,the POD activity decreased in both the inoculation group and control group of susceptible cultivar.The content of soluble protein has increased in the inoculation group and control group of resistant cultivar.And the content of soluble protein of susceptible cultivar inoculated was unchanged,while the soluble protein content of susceptible cultivar control group decreased.The results of development and hatching test of soybean against H.sojae showed:The resistant varieties not only reduced the invasion,but also inhibited the development of H.sojae.The development of most nematodes lags behind,resulting in a less number of cysts formed on the roots of soybeans.Root exudates of susceptible varieties promote the hatching of eggs,while the root exudates of resistant varieties can inhibit the hatching of the eggs,and with the growth period of resistant soybean seedlings have stronger inhibition effect on the hatching of the eggs.The hatching rate of cysts formed on different resistant soybean roots was different,so the hatching rate of collecting cysts on the roots of susceptible cultivar was higher than that of resistant cultivar.The results of different environmental conditions on the hatching of H.sojae showed that 25-30°C is the optimal temperature for hatching of H.sojae.Above 35°C and below10°C,the nematode hatching is inhibited.Metal ions Zn²⁺,Fe³⁺,Ca²⁺,Cu²⁺and Mg²⁺are at the concentration of 3 mmol/L inhibited the hatching of nematode eggs.Light（light/dark）8/16 h and 0/24 h conditions are most conducive to the hatching of the nematode eggs.In addition,hatching experiments of the cysts produced by the field harvesting and potting showed that the cysts collected in the field were more likely to hatch than the cysts produced by the pot.The results of the effects of H.sojae on soybean growth indicated that:The infection of soybean roots by H.sojae resulted in a decrease in the plant height,stem weight and pod number of susceptible soybeans compared with that of the control group.The resistant soybean plant height has no significant difference compared with the control group.There was no significant difference in root fresh weight of resistant soybean varieties with inoculationIn this paper,by studying the changes of physiological and biochemical indexes in soybean roots with inoculation,the most effective indexes for early identification of soybean resistance to H.sojae was MDA,followed by POD.and finally soluble protein.The activities of CAT,SOD,PAL and PPO are not suitable for early identification of soybean resistant to H.sojae.The results provide a basis for the early identification of soybean against H.sojae,and laid the foundation for studying the mechanism of soybean resistance to H.sojae.There is a further study on development and hatching of H.sojae infected with different resistant soybeans,which provided a reference for the research of soybean resistance to H.sojae.