| Soybean(Glycine max)is one of the important food crops in China,which is rich in protein,fat and other nutrients,and is a high-quality protein source.Soybean aphid(Aphis glycines)is a Hemiptera,Aphididae,Aphis,an insect that is one of the main pests of soybeans and is a worldwide pest that occurs in domestic soybean production areas and can cause more serious yield reductions in soybeans.At present,the control of soybean aphid is mainly by chemical control means,in order to avoid the "3R" problem,the screening of aphid-resistant germplasm resources is an effective way to control,therefore,this experiment was conducted as follows:(1)Soybean aphid incidence surveys were conducted on 250 soybean varieties in the experimental field,and the above soybean varieties were initially classified into five resistance classes based on aphid damage index and other indicators,namely,high resistance HR(aphid damage index I ≤ 20%),resistance R(20% < I ≤ 30%),moderate resistance MR(30% < I ≤40%),susceptible S(40% < I ≤ 50%),and high susceptibility HS(I > 50%).The results of soybean aphid resistance evaluation are: 41 varieties such as Ha1 evaluated as highly resistant;42 varieties such as Hefeng 26 evaluated as resistant;48 varieties such as Heihe 9 evaluated as moderately resistant;75 varieties such as Dongnong 4 evaluated as susceptible;44 varieties such as Suinong 22 evaluated as highly susceptible.(2)Hefeng 49(HR),Kenfeng 14(R),Jiyu 80(MR),Jiyu 47(S),and Jinong 29(HS)were screened among the five resistance classes for the determination of lipoxygenase(LOX),propylene oxide synthase(AOS),phenylalanine aminolase(PAL),and β-l,3 glucanase activities related to plant insect resistance under laboratory conditions,respectively.The experimental results showed that the enzyme activities of soybean of the five varieties of Hefeng 49,Kenfeng14,Jiyu 80,Jiyu 47 and Jinong 29 were significantly higher after aphid induction and showed significant differences at the adjacent time points of 0h,12 h,24h,48 h and 72 h.The peak of LOX activity mostly appeared at 12h-24 h after aphid induction,the peak of AOS activity mostly appeared at 24-48 h after aphid induction;the peak of PAL activity mostly appeared at 24h-48 h after aphid induction,and the β-1,3 glucanase activity was still high at 72 h.The aphid resistance of soybean varieties was closely related to LOX,AOS,PAL and β-l,3 glucanase activities,with the highly resistant variety Hefeng 49 and the resistant variety Kenfeng 14 having significantly higher enzyme activities than the moderately resistant variety Jiyu 80,the susceptible variety Jiyu 47 and the highly susceptible variety Jinong 29.(3)The correlation analysis between the key enzymes of soybean aphid resistance and aphid resistance showed that the activities of LOX,AOS,PAL and β-l,3 glucanase were negatively correlated with aphid damage index,among which AOS activity was significantly negatively correlated with aphid damage index;the activities of the four enzymes were positively correlated with aphid resistance in soybean,among which AOS and PAL activities were significantly positively correlated with aphid resistance.The higher the LOX,AOS,PAL andβ-l,3 glucanase activities,the lower the aphid damage index and the higher the aphid resistance,among which the AOS activity and PAL activity showed the most obvious performance.(4)Correlation analysis of aphid resistance in jasmonic acid and salicylic acid signaling pathway showed that The activities of LOX and AOS involved in the synthesis of jasmonic acid were positively correlated with the increase of PAL in salicylic acid synthesis and β-l,3glucanase activity increased by salicylic acid induction during 0-24 h,24-48 h and 48-72 h.It is concluded that jasmonic acid signaling pathway and salicylic acid signaling pathway are mutually reinforcing in the defense mechanism of soybean. |
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