| Rhopalosiphum padi is a kind of dominant population on wheat crops in China,mainly affecting the spike and flag leaf of wheat,leading to wheat yield reduction.Due to its long distance migration,it can transmit viruses that affect the photosynthetic respiration of wheat and cause crop damage.The wing pattern differentiation of aphids is to adapt to environmental changes,but the mechanism of wing differentiation remains to be further studied.The study of the mechanism of wing pattern differentiation of R.padi will not only help to understand its migration mechanism at the molecular level and lay a good foundation for its integrated control and prediction,but also help to further study the changes of wing patterns of other insects.In this study,we investigated the ecology of the wing type differentiation of R.padi by setting up different external environmental conditions.We investigated the changes of the titers of juvenile-protecting hormone and insulin by enzyme-linked immunoassay and the expression levels of genes such as insulin signaling pathway and differential analysis by RT-qpcr.The specific results are as follows:1、Effect of external environmental factors on wing type differentiation of R.padiBy setting different temperatures(10℃,20℃,25℃,30℃),different photoperiods(L/D=8 h/16 h,L/D=10 h/14 h,L/D=12 h/12 h,L/D=14 h/10 h),different crowding levels(5/dish,10/dish,20/dish,40/dish,60/dish),different starvation stresses(0 h,24 h,48 h,72 h)and two exogenous hormone concentrations(0%,1%,10%,100%)to study the effects of environmental factors on wing type differentiation of R.padi.The results showed that the winging rate was 34.0%and 41.1%at 10℃ and 30℃,respectively,which were significantly different from those at 20℃ and 25℃.The winged aphid formation was favored by both longer(L/D=10 h/14 h)and shorter(L/D=8 h/16 h)photoperiodic conditions,and the winged aphid formation was significantly different at L/D=8 h/16 h and L/D=10 h/14 h.The rate of winged aphids reached 21.6%and 25.3%under L/D=8 h/16 h and L/D=10 h/14 h treatments,respectively,and the differences between L/D=8 h/16 h and L/D=10 h/14 h,L/D=12 h/12 h and L/D=14 h/10 h treatments were not significant while the differences between L/D=8 h/16 h and L/D=10 h/14 h treatments and L/D=12 h/12 h,L/D=14 h/10 h treatments were all highly significant while the differences between L/D=8 h/16 h and L/D=10 h/14 h treatments and L/D=12 h/12 h,L/D=14 h/8 h.The differences were not significant between the 5/dish and 10/dish treatments,highly significant between the 5/dish and 10/dish and other treatments,and significant between the 20/dish,40/dish and 60/dish treatments;starvation treatment After starvation treatment,not only the phenotype of contemporary aphids was affected,but also the phenotypic changes of the second generation of aphids.For example,at 24 h of starvation,the winging rate of the mother generation was only 11.3%,56.3%of the second generation of winged adult aphids and 79.6%of the second generation of wingless adult aphids,while at 48 h of starvation,the winging rate of the mother generation was 7.4%,74.0%of the second generation of winged adult aphids and 41.5%of the second generation of wingless adult aphids.Both the exogenous hormone juvenile-preserving hormone analogue(ZR515)and ecdysone analogue(20E)had significant inhibitory effects on wing differentiation in R.padi.2、Variation of hormone titers in different wing types of R.padiThe differences in the titers of different hormones in winged and wingless aphids were determined by enzyme-linked immunoassay.The results showed that the titers of juvenile hormone,ecdysone and insulin in winged and wingless aphids were significantly different.For example,the titer of juvenile hormone was 76.0897 ng/mg in adult winged aphids and 88.9103 ng/mg in wingless adult aphids,with significant differences between them;the titer of ecdysteroid was 7.5402 ng/mg in adult winged aphids and 11.0772 ng/mg in wingless adult aphids.The difference between the two was significant;the insulin titer was only 12.1028 ng/mg in the winged adult aphid and 27.5234 ng/mg in the wingless adult aphid,and the difference between the two was also significant.It is inferred that the wing type differentiation of R.padi may be related to the juvenile preservation hormone,ecdysteroid and insulin signaling pathways.3、Expression analysis of genes related to hormone signaling pathwayThe relative expression of eight genes related to the hormone pathway of the winged aphid and the wingless aphid were analyzed by RT-qpcr technique.The relative expression of all eight juvenile-preserving hormone pathway-related genes differed,with significant differences in the relative expression of the gene FTase in winged and wingless aphids of R.padi.and the relative expression of genes FNTA,IDS,JHAMT1 and JHAMT2 in the winged and wingless aphids of the grain constrictor aphid was highly significant;The relative expression of all six ecdysone pathway-related genes differed,with the expression of genes Hr39 and CBWD differing significantly in winged and wingless aphids,and the expression of genes lola2,CYP450,and lola3 were highly significant in winged and wingless aphids;The relative expression of all six insulin hormone pathway-related genes differed,as the relative expression of KCNN and FOX2 differed significantly in winged and wingless aphids,the relative expression of genes FOXD1 and FOXD3 in winged and wingless aphids were highly significant.It can be seen that wing type differentiation of R.padi is related to hormonal changes in the aphid and the involvement of related genes. |
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