At the 24th and 48th hours after being infected by T. trifolii, jasmonic acid content of Zhongmu No. 1 was significantly influenced by the strain of T. trifolii (24 h: F_2,14 = 28.44, p < 0.05; 48 h: F_2,14 = 17.03, p < 0.05) (Figure 2a). However, the 6th hour after being infected by two strains of T. trifolii, jasmonic acid content of Zhongmu No. 1 had no significant difference from the blank control. Additionally, at the 24th and 48th hours after being infected by T. trifolii, the jasmonic acid content of alfalfa infected by S-aphids (24 h, 6.89 ± 1.08 mg/g; 48 h, 5.20 ± 0.76 mg/g) was significantly higher than of that infected by R-aphids (24 h, 5.17 ± 0.55 mg/g; 48 h, 3.76 ± 0.62 mg/g) (24 h, z = 1.94, p < 0.05; 48 h, z = 2.08, p < 0.05), and they were both significantly higher than the blank control (24 h, 3.03 ± 0.29 mg/g; 48 h, 3.11 ± 0.20 mg/g) (24 h, S-aphid-infected vs. control treatment, z = 6.23, p < 0.05; 24 h, R-aphid-infected vs. control treatment, z = 12.52, p < 0.05; 48 h, S-aphid-infected vs. control treatment, z = 9.52, p < 0.05; 48 h, R-aphid-infected vs. control treatment, z = 8.52, p < 0.05).

At the 6th and 24th hours after being infected by T. trifolii, salicylic acid content of Zhongmu No. 1 was significantly influenced by the strain of T. trifolii (6 h: F_2,14 = 61.91, p < 0.05; 24 h: F_2,14 = 29.87, p < 0.05) (Figure 2b). Besides, at the 6th and 24th hours after being infected by T. trifolii, salicylic acid content of alfalfa infected by R-aphids (6 h, 8.18 ± 0.55 mg/g; 24 h, 7.07 ± 0.70 mg/g) was significantly higher than that infected by S-aphids (6 h, 6.61 ± 0.71 mg/g; 24 h, 5.91 ± 0.80 mg/g) (6 h, z = 11.76, p < 0.05; 24 h, z = 6.64, p < 0.05), and they both were significantly higher than the blank control (6 h, 4.10 ± 0.41 mg/g; 24 h, 4.20 ± 0.32 mg/g) (6 h, S-aphid-infected vs. control treatment, z = 5.32, p < 0.05; 6 h, R-aphid-infected vs. control treatment, z = 11.20, p < 0.05; 24 h, S-aphid-infected vs. control treatment, z = 5.94, p < 0.05; 24 h, R-aphid-infected vs. control treatment, z = 16.54, p < 0.05). However, at the 48th hour after being infected by two strains of T. trifolii, the salicylic acid content of Zhongmu No. 1 had returned to a level which was of no significant difference compared to the blank control.

At the 24th and 48th hours after being infected by T. trifolii, expression level of AOS, a key synthetic gene of jasmonic acid was significantly influenced by the strain of T. trifolii (24 h: F_2,14 = 97.02, p < 0.05; 48 h: F_2,14 = 44.62, p < 0.05) (Figure 2c). However, at the 6th hour after being infected by two strains of T. trifolii, the AOS expression level of Zhongmu No. 1 had no significant difference from the blank control. Additionally, at the 24th and 48th hours after being infected by T. trifolii, the AOS expression level of Zhongmu No. 1 infected by S-aphids (24 h, 4.54 ± 0.52; 48 h, 3.17 ± 0.46) was significantly higher than of that infected by R-aphids (24 h, 3.15 ± 0.54; 48 h, 2.57 ± 0.50) (24 h, z = 11.24, p < 0.05; 48 h, z = 7.54, p < 0.05), and they were both significantly higher than the blank control (24 h, 1.02 ± 0.08; 48 h, 0.99 ± 0.10) (24 h, S-aphid-infected vs. control treatment, z = 12.95, p < 0.05; 24 h, R-aphid-infected vs. control treatment, z = 16.24, p < 0.05; 48 h, S-aphid-infected vs. control treatment, z = 11.25, p < 0.05; 48 h, R-aphid-infected vs. control treatment, z = 12.54, p < 0.05). At the 72nd hour after being infected by T. trifolii, there was no significant difference in expression levels of AOS between Zhongmu No. 1 infected by R-aphids (72 h, 1.48 ± 0.30) and S-aphids (72 h, 2.09 ± 0.44), but they were both significantly higher than the blank control (72 h, 1.05 ± 0.08) (72 h, R-aphid-infected vs. control treatment, z = 13.54, p < 0.05; 72 h, S-aphid-infected vs. control treatment, z = 12.65, p < 0.05).

At the 24th and 48th hour after being infected by T. trifolii, expression levels of LOX, a key synthetic gene of jasmonic acid, was significantly influenced by the strain of T. trifolii (24 h: F_2,14 = 94.17, p < 0.05; 48 h: F_2,14 = 55.87, p < 0.05) (Figure 2d). However, at the 6th hour after being infected by two strains of T. trifolii, the LOX expression level of Zhongmu No. 1 had no significant difference from the blank control. Additionally, at the 24th and 48th hours after being infected by T. trifolii, the LOX expression level of Zhongmu No. 1 infected by S-aphids (24 h, 3.76 ± 0.46; 48 h, 3.42 ± 0.38) was significantly higher than of that infected by R-aphids (24 h, 2.82 ± 0.24; 48 h, 3.00 ± 0.43) (24 h, z = 16.85, p < 0.05; 48 h, z = 8.64, p < 0.05), and they were both significantly higher than the blank control (24 h, 1.06 ± 0.15; 48 h, 1.03 ± 0.07) (24 h, S-aphid-infected vs. control treatment, z = 12.54, p < 0.05; 24 h, R-aphid-infected vs. control treatment, z = 10.57, p < 0.05; 48 h, S-aphid-infected vs. control treatment, z = 16.78, p < 0.05; 48 h, R-aphid-infected vs. control treatment, z = 13.57, p < 0.05). At the 72nd hour after being infected by T. trifolii, there was no significant difference in expression level of LOX between Zhongmu No. 1 infected by R-aphids (72 h, 2.60 ± 0.38) and S-aphids (72 h, 2.06 ± 0.52), but they were both significantly higher than the blank control (72 h, 1.06 ± 0.09) (72 h, R-aphid-infected vs. control treatment, z = 13.89, p < 0.05; 72 h, S-aphid-infected vs. control treatment, z = 19.85, p < 0.05).

At the 24th and 48th hours after being infected by T. trifolii, expression level of ICS, a key synthetic gene of salicylic acid was significantly influenced by the strain of T. trifolii (24 h: F_2,14 = 53.64, p < 0.05; 48 h: F_2,14 = 51.62, p < 0.05) (Figure 2e). At the 6th hour after being infected by two strains of T. trifolii, there was no significant difference in expression level of ICS between Zhongmu No. 1 infected by R-aphids (6 h, 1.66 ± 0.25) and S-aphids (6 h, 1.89 ± 0.11), but they were both significantly higher than the blank control (6 h, 1.04 ± 0.13) (6 h, R-aphid-infected vs. control treatment, z = 10.94, p < 0.05; 6 h, S-aphid-infected vs. control treatment, z = 13.84, p < 0.05). At the 24th and 48th hours after being infected by T. trifolii, the ICS expression level of Zhongmu No. 1 infected by R-aphids (24 h, 3.44 ± 0.37; 48 h, 3.00 ± 0.51) was significantly higher than that infected by S-aphids (24 h, 2.79 ± 0.34; 48 h, 2.43 ± 0.41) (24 h, z = 11.24, p < 0.05; 48 h, z = 5.84, p < 0.05), and they were both significantly higher than the blank control (24 h, 1.07 ± 0.13; 48 h, 1.04 ± 0.14) (24 h, S-aphid-infected vs. control treatment, z = 9.51, p < 0.05; 24 h, R-aphid-infected vs. control treatment, z = 6.54, p < 0.05; 48 h, S-aphid-infected vs. control treatment, z = 11.27, p < 0.05; 48 h, R-aphid-infected vs. control treatment, z = 9.65, p < 0.05). However, at the 72nd hour after being infected by T. trifolii, only the ICS expression level of Zhongmu No. 1 infected by R-aphids (72 h, 0.99 ± 0.13) was significantly higher than the blank control (72 h, R-aphid-infected vs. control treatment, z = 8.64, p < 0.05), ICS expression level of Zhongmu No. 1 infected by S-aphids had returned to a level which was of no significant difference compared to the blank control.

At the 24th and 48th hours after being infected by T. trifolii, expression level of PAL, a key synthetic gene of salicylic acid was significantly influenced by the strain of T. trifolii (24 h: F_2,14 = 26.70, p < 0.05; 48 h: F_2,14 = 14.63, p < 0.05) (Figure 2f). At the 6th hour after being infected by two strains of T. trifolii, there was no significant difference in expression levels of PAL between Zhongmu No. 1 infected by R-aphids (6 h, 2.88 ± 0.19) and S-aphids (6 h, 2.74 ± 0.47), but they were both significantly higher than the blank control (6 h, 1.04 ± 0.16) (6 h, R-aphid-infected vs. control treatment, z = 8.54, p < 0.05; 6 h, S-aphid-infected vs. control treatment, z = 7.51, p < 0.05). At the 24th and 48th hours after being infected by T. trifolii, PAL expression level of Zhongmu No. 1 infected by R-aphids (24 h, 5.43 ± 0.55; 48 h, 4.28 ± 0.59) was significantly higher than of that infected by S-aphids (24 h, 4.17 ± 0.73; 48 h, 3.18 ± 0.56) (24 h, z = 11.95, p < 0.05; 48 h, z = 16.85, p < 0.05), and they were both significantly higher than the blank control (24 h, 1.08 ± 0.15; 48 h, 1.03 ± 0.16) (24 h, S-aphid-infected vs. control treatment, z = 9.51, p < 0.05; 24 h, R-aphid-infected vs. control treatment, z = 9.54, p < 0.05; 48 h, S-aphid-infected vs. control treatment, z = 11.27, p < 0.05; 48 h, R-aphid-infected vs. control treatment, z = 4.56, p < 0.05). However, at the 72nd hour after being infected by two strains of T. trifolii, the PAL expression level of Zhongmu No. 1 returned to a level which was of no significant difference compared to the blank control.

At the 6th, 24th, and 48th hours after being infected by T. trifolii, there was no significant difference in jasmonic acid content between WL343 leaves infected by S-aphids and R-aphids (Figure 3a). At the 6th hour after being infected by two strains of T. trifolii, jasmonic acid content of Wl343 had no significant difference compared to the blank control. At the 24th and 48th hours after being infected by T. trifolii, the jasmonic acid contents of WL343 infected by S-aphids (24 h, 5.45 ± 0.32 mg/g; 48 h, 5.01 ± 0.70 mg/g) and R-aphids (24 h, 3.70 ± 0.59 mg/g; 48 h, 4.42 ± 0.44 mg/g) were both significantly higher than the blank control (24 h, 2.54 ± 0.20 mg/g; 48 h, 2.41 ± 0.15 mg/g) (24 h, S-aphid-infected vs. control treatment, z = 7.52, p < 0.05; 24 h, R-aphid-infected vs. control treatment, z = 5.94, p < 0.05; 48 h, S-aphid-infected vs. control treatment, z = 12.84, p < 0.05; 48 h, R-aphid-infected vs. control treatment, z = 10.54, p < 0.05).

At the 6th, 24th, and 48th hours after being infected by T. trifolii, there was no significant difference in salicylic acid content between WL343 leaves infected by S-aphids and R-aphids (Figure 3b). At the 6th and 24th hours after being infected by T. trifolii, the salicylic acid contents of WL343 infected by S-aphids (6 h, 5.52 ± 0.42 mg/g; 24 h, 5.13 ± 0.45 mg/g) and R-aphid (6 h, 6.25 ± 0.68 mg/g; 24 h, 4.73 ± 0.46 mg/g) were both significantly higher than the blank control (6 h, 3.47 ± 0.53 mg/g; 24 h, 3.57 ± 0.62 mg/g) (6 h, S-aphid-infected vs. control treatment, z = 11.95, p < 0.05; 6 h, R-aphid-infected vs. control treatment, z = 16.25, p < 0.05; 24 h, S-aphid-infected vs. control treatment, z = 13.54, p < 0.05; 24 h, R-aphid-infected vs. control treatment, z = 16.52, p < 0.05). However, at the 48th hour after being infected by two strains of T. trifolii, the salicylic acid content of WL343 had returned to a level which was of no significant difference compared to the blank control.

At the 6th, 24th, and 48th hours after being infected by T. trifolii, there was no significant difference in the expression levels of AOS (a key synthetic gene of jasmonic acid) of WL343 leaves infected by S-aphids and R-aphids (Figure 3c). At the 6th hour after being infected by two strains of T. trifolii, the AOS expression level of Wl343 had no significant difference from the blank control. At the 24th and 48th hours after being infected by T. trifolii, the AOS expression levels of WL343 infected by S-aphids (24 h, 3.70 ± 0.52; 48 h, 2.87 ± 0.55) and R-aphids (24 h, 3.70 ± 0.59; 48 h, 4.42 ± 0.44) were both significantly higher than the blank control (24 h, 3.67 ± 0.53; 48 h, 2.57 ± 0.50) (24 h, S-aphid-infected vs. control treatment, z = 15.87, p < 0.05; 24 h, R-aphid-infected vs. control treatment, z = 8.65, p < 0.05; 48 h, S-aphid-infected vs. control treatment, z = 8.22, p < 0.05; 48 h, R-aphid-infected vs. control treatment, z = 13.94, p < 0.05). At the 72nd hour after being infected by two strains of T. trifolii, the AOS expression level of WL343 had returned to a level which was of no significant difference compared to the blank control.

At the 6th, 24th, and 48th hours after being infected by T. trifolii, there was no significant difference in the expression levels of LOX (a key synthetic gene of jasmonic acid) of WL343 leaves infected by S-aphids and R-aphids (Figure 3d). At the 6th hour after being infected by two strains of T. trifolii, the LOX expression level of Wl343 had no significant difference from the blank control. At the 24th and 48th hours after being infected by T. trifolii, the LOX expression levels of WL343 infected by S-aphids (24 h, 2.44 ± 0.30; 48 h, 2.31 ± 0.26) and R-aphids (24 h, 3.70 ± 0.59; 48 h, 4.42 ± 0.44) were both significantly higher than that of the blank control (24 h, 2.30 ± 0.32; 48 h, 2.15 ± 0.27) (24 h, S-aphid-infected vs. control treatment, z = 7.54, p < 0.05; 24 h, R-aphid-infected vs. control treatment, z = 12.94, p < 0.05; 48 h, S-aphid-infected vs. control treatment, z = 12.94, p < 0.05; 48 h, R-aphid-infected vs. control treatment, z = 16.84, p < 0.05). At the 72nd hour after being infected by two strains of T. trifolii, the LOX expression level of WL343 had returned to a level which had no significant difference compared to the blank control.

At the 6th, 24th, and 48th hours after being infected by T. trifolii, there was no significant difference in the expression levels of ICS (a key synthetic gene of salicylic acid) of WL343 leaves infected by S-aphids and R-aphids (Figure 3e). At the 6th, 24th and 48th hours after being infected by T. trifolii, the ICS expression levels of WL343 infected by S-aphids (6 h, 1.72 ± 0.26; 24 h, 2.44 ± 0.30; 48 h, 2.31 ± 0.26) and R-aphids (6 h, 1.75 ± 0.13; 24 h, 3.70 ± 0.59; 48 h, 4.42 ± 0.44) were both significantly higher than that of the blank control (6 h, 1.75 ± 0.13; 24 h, 2.30 ± 0.32; 48 h, 2.15 ± 0.27) (6 h, S-aphid-infected vs. control treatment, z = 5.44, p < 0.05; 6 h, R-aphid-infected vs. control treatment, z = 6.1, p < 0.05; 24 h, S-aphid-infected vs. control treatment, z = 13.52, p < 0.05; 24 h, R-aphid-infected vs. control treatment, z = 11.24, p < 0.05; 48 h, S-aphid-infected vs. control treatment, z = 18.52, p < 0.05; 48 h, R-aphid-infected vs. control treatment, z = 12.94, p < 0.05). At the 72nd hour after being infected by two strains of T. trifolii, ICS expression level of WL343 had both returned to a level which had no significant difference compared to the blank control.

At the 6th, 24th, and 48th hours after being infected by T. trifolii, there was no significant difference in expression level of PAL (a key synthetic gene of salicylic acid) of WL343 leaves infected by S-aphids and R-aphids (Figure 3f). At the 6th, 24th, and 48th hours after being infected by T. trifolii, the PAL expression levels of WL343 infected by S-aphids (6 h, 2.12 ± 0.27; 24 h, 3.28 ± 0.25; 48 h, 2.95 ± 0.34) and R-aphids (6 h, 2.35 ± 0.24; 24 h, 3.44 ± 0.27; 48 h, 3.22 ± 0.50) were both significantly higher than the blank control (6 h, 1.07 ± 0.06; 24 h, 1.05 ± 0.13; 48 h, 1.01 ± 0.09) (6 h, S-aphid-infected vs. control treatment, z = 5.44, p < 0.05; 6 h, R-aphid-infected vs. control treatment, z = 8.52, p < 0.05; 24 h, S-aphid-infected vs. control treatment, z = 12.56, p < 0.05; 24 h, R-aphid-infected vs. control treatment, z = 11.25, p < 0.05; 48 h, S-aphid-infected vs. control treatment, z = 13.59, p < 0.05; 48 h, R-aphid-infected vs. control treatment, z = 11.56, p < 0.05). At the 72nd hour after being infected by two strains of T. trifolii, the PAL expression level of WL343 had returned to a level which had no significant difference compared to the blank control.

At the 24th and 48th hours after being infiltrated by T. trifolii’s saliva, the jasmonic acid content of Zhongmu No. 1 was significantly influenced by the strain of T. trifolii (24 h: F_2,14 = 37.71, p < 0.05; 48 h: F_2,14 = 17.02, p < 0.05) (Figure 4a). However, at the 6th hour after being infiltrated by two strains of T. trifolii’s saliva, the jasmonic acid content of Zhongmu No. 1 had no significant difference from the blank control. Additionally, at the 24th and 48th hours after being infiltrated by T. trifolii’s saliva, the jasmonic acid content of alfalfa infiltrated by S-saliva (24 h, 5.66 ± 0.48 mg/g; 48 h, 4.55 ± 0.42 mg/g) was significantly higher than of that infiltrated by R-saliva (24 h, 4.74 ± 0.48 mg/g; 48 h, 3.37 ± 0.38 mg/g) (24 h, z = 3.42, p < 0.05; 48 h, z = 2.47, p < 0.05), and they both were significantly higher than the blank control (24 h, 3.12 ± 0.13 mg/g; 48 h, 3.14 ± 0.08 mg/g) (24 h, S-saliva infiltration vs. control treatment, z = 5.74, p < 0.05; 24 h, R-saliva infiltration vs. control treatment, z = 9.13, p < 0.05; 48 h, S-saliva infiltration vs. control treatment, z = 16.75, p < 0.05; 48 h, R-saliva infiltration vs. control treatment, z = 10.65, p < 0.05).

At the 6th and 24th hours after being infiltrated by T. trifolii’s saliva, the salicylic acid content of Zhongmu No. 1 was significantly influenced by the strain of T. trifolii (6 h: F_2,14 = 122.47, p < 0.05; 24 h: F_2,14 = 78.67, p < 0.05) (Figure 4b). Additionally, at the 6th and 24th hours after being infiltrated by T. trifolii, the salicylic acid content of alfalfa infiltrated by R-saliva (6 h, 8.49 ± 0.76 mg/g; 24 h, 7.97 ± 0.69 mg/g) was significantly higher than that infiltrated by S-saliva (6 h, 6.80 ± 0.76 mg/g; 24 h, 6.71 ± 0.38 mg/g) (6 h, z = 9.24, p < 0.05; 24 h, z = 14.72, p < 0.05), and they both were significantly higher than the blank control (6 h, 3.88 ± 0.37 mg/g; 24 h, 3.54 ± 0.49 mg/g) (6 h, S-saliva infiltration vs. control treatment, z = 16.52, p < 0.05; 6 h, R-saliva infiltration vs. control treatment, z = 14.52, p < 0.05; 24 h, S-saliva infiltration vs. control treatment, z = 11.63, p < 0.05; 24 h, R-saliva infiltration vs. control treatment, z = 21.41, p < 0.05). However, at the 48th hour after being infiltrated by two strains of T. trifolii’s saliva, the salicylic acid content of Zhongmu No. 1 had returned to a level which had no significant difference compared to the blank control.

At the 24th and 48th hours after being infiltrated by T. trifolii’s saliva, expression levels of AOS, a key synthetic gene of jasmonic acid, were significantly influenced by the strain of T. trifolii (24 h: F_2,14 = 102.86, p < 0.05; 48 h: F_2,14 = 42.15, p < 0.05) (Figure 4c). At the 6th hour after being infiltrated by two strains of T. trifolii’s saliva, the AOS expression level of Zhongmu No. 1 had no significant difference from that of the blank control. Additionally, at the 24th and 48th hours after being infiltrated by T. trifolii, the AOS expression level of Zhongmu No. 1 infiltrated by S-saliva (24 h, 5.56 ± 0.49; 48 h, 4.24 ± 0.91) was significantly higher than of that infiltrated by R-saliva (24 h, 3.60 ± 0.62; 48 h, 2.61 ± 0.49) (24 h, z = 2.94, p < 0.05; 48 h, z = 11.52, p < 0.05), and they were both significantly higher than the blank control (24 h, 1.05 ± 0.08; 48 h, 1.05 ± 0.07) (24 h, S-saliva infiltration vs. control treatment, z = 21.48, p < 0.05; 24 h, R-saliva infiltration vs. control treatment, z = 16.74, p < 0.05; 48 h, S-saliva infiltration vs. control treatment, z = 16.74, p < 0.05; 48 h, R-saliva infiltration vs. control treatment, z = 11.44, p < 0.05). At the 72nd hour after being infected by T. trifolii, there was no significant difference in expression level of AOS between Zhongmu No. 1 infected by R-aphids (72 h, 2.18 ± 0.28) and S-aphids (72 h, 3.07 ± 0.32), but they were both significantly higher than the blank control (72 h, 1.04 ± 0.07) (72 h, R-saliva infiltration vs. control treatment, z = 20.14, p < 0.05; 72 h, S-saliva infiltration vs. control treatment, z = 14.56, p < 0.05).

At the 24th and 48th hours after being infiltrated by T. trifolii’s saliva, the expression level of LOX, a key synthetic gene of jasmonic acid, was significantly influenced by the strain of T. trifolii (24 h: F_2,14 = 102.54, p < 0.05; 48 h: F_2,14 = 52.81, p < 0.05) (Figure 4d). At the 6th hour after being infiltrated by two strains of T. trifolii’s saliva, the LOX expression level of Zhongmu No. 1 had no significant difference from the blank control. Additionally, at the 24th and 48th hours after being infiltrated by T. trifolii’s saliva, the LOX expression level of Zhongmu No. 1 infiltrated by S-saliva (24 h, 3.63 ± 0.51; 48 h, 3.62 ± 0.47) was significantly higher than of that infiltrated by S-aphids (24 h, 2.86 ± 0.44; 48 h, 3.17 ± 0.29) (24 h, z = 22.56, p < 0.05; 48 h, z = 14.63, p < 0.05), and they were both significantly higher than the blank control (24 h, 2.86 ± 0.44; 48 h, 3.17 ± 0.29) (24 h, S-saliva infiltration vs. control treatment, z = 13.56, p < 0.05; 24 h, R-saliva infiltration vs. control treatment, z = 10.57, p < 0.05; 48 h, S-saliva infiltration vs. control treatment, z = 21.43, p < 0.05; 48 h, R-saliva infiltration vs. control treatment, z = 15.92, p < 0.05). At the 72nd hour after being infiltrated by T. trifolii’s saliva, there was no significant difference in expression levels of LOX between Zhongmu No. 1 being infiltrated by R-saliva (72 h, 2.23 ± 0.27) and S-saliva (72 h, 1.97 ± 0.38), but they were both significantly higher than the blank control (72 h, 1.05 ± 0.09) (72 h, R-saliva infiltration vs. control treatment, z = 22.65, p < 0.05; 72 h, S-saliva infiltration vs. control treatment, z = 13.65, p < 0.05).

At the 24th, 48th, and 72nd hours after being infiltrated by T. trifolii’s saliva, expression levels of ICS, a key synthetic gene of salicylic acid was significantly influenced by the strain of T. trifolii (24 h: F2,14 = 66.74, p < 0.05; 48 h: F2,14 = 34.14, p < 0.05; 48 h: F2,14 = 22.62, p < 0.05) (Figure 4e). At the 6th hour after being infiltrated by T. trifolii’s saliva, there was no significant difference in the expression levels of ICS between Zhongmu No. 1 being infiltrated by R-saliva (6 h, 1.97 ± 0.24) and S-saliva (6 h, 1.81 ± 0.25), but they were both significantly higher than the blank control (6 h, 1.07 ± 0.04) (6 h, R-saliva infiltration vs. control treatment, z = 13.45, p < 0.05; 6 h, S-saliva infiltration vs. control treatment, z = 9.14, p < 0.05). At the 24th, 48th, and 48th hour after being infiltrated by T. trifolii’s saliva, ICS expression level of Zhongmu No. 1 infiltrated by R-saliva (24 h, 4.16 ± 0.49; 48 h, 3.05 ± 0.51; 72 h, 1.88 ± 0.18) was significantly higher than that infiltrated by S-saliva (24 h, 3.39 ± 0.56; 48 h, 2.74 ± 0.51; 72 h, 1.59 ± 0.25) (24 h, z = 16.52, p < 0.05; 48 h, z = 16.94, p < 0.05; 72 h, z = 11.95, p < 0.05). At the 6th, 24th, and 48th hour after being infiltrated by two strains T. trifolii’s saliva, ICS expression level of Zhongmu No. 1 were significantly higher than the blank control (6 h, 1.07 ± 0.04; 24 h, 1.06 ± 0.06; 48 h, 1.06 ± 0.05) (6 h, S-saliva infiltration vs. control treatment, z = 12.11, p < 0.05; 6 h, R-saliva infiltration vs. control treatment, z = 13.56, p < 0.05; 24 h, S-saliva infiltration vs. control treatment, z = 18.54, p < 0.05; 24 h, R-saliva infiltration vs. control treatment, z = 11.94, p < 0.05; 48 h, S-saliva infiltration vs. control treatment, z = 11.25, p < 0.05; 48 h, R-saliva infiltration vs. control treatment, z = 13.94, p < 0.05). However, at the 72nd hour after being infiltrated by T. trifolii’s saliva, only the ICS expression level of Zhongmu No. 1 infiltrated by R-saliva (72 h, 1.84 ± 0.2) was significantly higher than the blank control (72 h, 1.08 ± 0.07) (72 h, R-saliva infiltration vs. control treatment, z = 22.64, p < 0.05); the ICS expression level of Zhongmu No. 1 infiltrated by S-saliva had returned to a level which had no significant difference compared to the blank control.

At the 24th and 48th hour after being infiltrated by T. trifolii’s saliva, expression level of PAL, a key synthetic gene of salicylic acid was significantly influenced by the strain of T. trifolii (24 h: F_2,14 = 181.23, p < 0.05; 48 h: F_2,14 = 16.05, p < 0.05) (Figure 4f). At the 6th hour after being infiltrated by T. trifolii’s saliva, there was no significant difference in expression level of PAL between Zhongmu No. 1 being infiltrated by R-saliva and S-saliva, and neither of them were significantly different from the blank control. At the 24th and 48th hour after being infiltrated by T. trifolii, PAL expression level of Zhongmu No. 1 infiltrated by R-saliva (24 h, 4.06 ± 0.33; 48 h, 2.41 ± 0.36) was significantly higher than infiltrated by S-saliva (24 h, 3.35 ± 0.41; 48 h, 2.17 ± 0.52) (24 h, z = 16.84, p < 0.05; 48 h, z = 11.23, p < 0.05), and they were both significantly higher than the blank control (24 h, 1.18 ± 0.12; 48 h, 1.06 ± 0.13) (24 h, S-saliva infiltration vs. control treatment, z = 12.05, p < 0.05; 24 h, R-saliva infiltration vs. control treatment, z = 8.61, p < 0.05; 48 h, S-aphid-infected vs. control treatment, z = 11.27, p < 0.05; 48 h, R-saliva infiltration vs. control treatment, z = 12.94, p < 0.05). However, at the 72nd hour after being infiltrated by two strains of T. trifolii’s saliva, PAL expression level of Zhongmu No. 1 returned to a level which had no significant difference compared to the blank control.

At the 6th, 24th, and 48th hours after being infiltrated by T. trifolii’s saliva, there was no significant difference in jasmonic acid content between WL343 leaves infiltrated by S-saliva and R-saliva (Figure 5a). At the 6th hour after being infiltrated by two strains of T. trifolii’s saliva, the jasmonic acid content of Wl343 was not significantly different from the blank control. At the 24th hour after being infiltrated by T. trifolii, the jasmonic acid contents of WL343 infiltrated by S-aphids (24 h, 4.87 ± 0.66) and R-aphids (24 h, 4.77 ± 0.41) were both significantly higher than the blank control (24 h, 3.10 ± 0.18) (24 h, S-saliva infiltration vs. control treatment, z = 15.94, p < 0.05; 24 h, R-saliva infiltration vs. control treatment, z = 15.64, p < 0.05).

At the 6th, 24th, and 48th hour after being infiltrated by T. trifolii’s saliva, there was no significant difference in salicylic acid content between WL343 leaves infiltrated by S-saliva and R-saliva (Figure 5b). At the 6th and 24th hours after being infiltrated by T. trifolii’s saliva, the salicylic acid content of WL343 infiltrated by S-saliva (6 h, 7.00 ± 0.68 mg/g; 24 h, 5.52 ± 0.50 mg/g) and R-saliva (6 h, 7.26 ± 1.06 mg/g; 24 h, 5.59 ± 0.90 mg/g) were both significantly higher than the blank control (6 h, 3.37 ± 0.36 mg/g; 24 h, 3.32 ± 0.23 mg/g) (6 h, S-saliva infiltration vs. control treatment, z = 13.54, p < 0.05; 6 h, R-saliva infiltration vs. control treatment, z = 11.85, p < 0.05; 24 h, S-saliva infiltration vs. control treatment, z = 9.14, p < 0.05; 24 h, R-saliva infiltration vs. control treatment, z = 12.65, p < 0.05). However, at the 48th hour after being infiltrated by two strains of T. trifolii’s saliva, the salicylic acid content of WL343 had returned to a level which had no significant difference compared to the blank control.

At the 6th, 24th, and 48th hours after being infiltrated by T. trifolii’s saliva, there was no significant difference in the expression level of AOS (a key synthetic gene of jasmonic acid) of WL343 leaves infiltrated by S-saliva and R-saliva (Figure 5c). At the 6th hour after being infiltrated by two strains of T. trifolii’s saliva, the AOS expression levels of Wl343 have no significant difference from the blank control. At the 24th and 48th hours after being infiltrated by T. trifolii’s saliva, the AOS expression levels of WL343 infiltrated by S-saliva (24 h, 3.77 ± 0.47; 48 h, 2.84 ± 0.45) and R-saliva (24 h, 3.61 ± 0.29; 48 h, 2.65 ± 0.64) were both significantly higher than the blank control (24 h, 1.10 ± 0.04; 48 h, 1.05 ± 0.09) (24 h, S-saliva infiltration vs. control treatment, z = 10.65, p < 0.05; 24 h, R-saliva infiltration vs. control treatment, z = 16.84, p < 0.05; 48 h, S-saliva infiltration vs. control treatment, z = 13.64, p < 0.05; 48 h, R-saliva infiltration vs. control treatment, z = 11.08, p < 0.05). At the 72nd hour after being infiltrated by T. trifolii’s saliva, the AOS expression level of WL343 had returned to a level which had no significant difference compared to the blank control.

At the 6th, 24th, 48th, and 72nd hours after being infiltrated by T. trifolii’s saliva, there was no significant difference in the expression levels of LOX (a key synthetic gene of jasmonic acid) of WL343 leaves infiltrated by S-saliva and R-saliva (Figure 5d). At the 6th hour after being infiltrated by two strains of T. trifolii’s saliva, the LOX expression level of Wl343 had no significantl difference from the blank control. At the 24th and 48th hours after being infiltrated by T. trifolii’s saliva, the LOX expression levels of WL343 infiltrated by S-saliva (24 h, 2.51 ± 0.33; 48 h, 2.25 ± 0.43) and R-aphids (24 h, 2.44 ± 0.23; 48 h, 2.19 ± 0.30) were both significantly higher than the blank control (24 h, 1.10 ± 0.10; 48 h, 1.10 ± 0.02) (24 h, S-saliva infiltration vs. control treatment, z = 5.64, p < 0.05; 24 h, R-saliva infiltration vs. control treatment, z = 12.94, p < 0.05; 48 h, S-saliva infiltration vs. control treatment, z = 3.94, p < 0.05; 48 h, R-saliva infiltration vs. control treatment, z = 15.26, p < 0.05). At the 72nd hour after being infiltrated by two strains of T. trifolii’s saliva, the LOX expression level of WL343 returned to a level which had no significant difference compared to the blank control.

At the 6th, 24th, 48th, and 72nd hours after being infiltrated by T. trifolii’s saliva, there was no significant difference in the expression levels of ICS (a key synthetic gene of salicylic acid) of WL343 leaves infiltrated by S-saliva and R-saliva (Figure 5e). At the 6th, 24th, and 48th hours after being infiltrated by T. trifolii’s saliva, ICS expression level of WL343 infiltrated by S-aphids (6 h, 2.32 ± 0.35; 24 h, 3.02 ± 0.59; 48 h, 2.63 ± 0.40) and R-saliva (6 h, 2.37 ± 0.39; 24 h, 3.50 ± 0.51; 48 h, 2.52 ± 0.37) were both significantly higher than the blank control (6 h, 1.09 ± 0.06; 24 h, 1.10 ± 0.11; 48 h, 1.07 ± 0.03) (6 h, S-saliva infiltration vs. control treatment, z = 15.84, p < 0.05; 6 h, R-saliva infiltration vs. control treatment, z = 20.44, p < 0.05; 24 h, S-saliva infiltration vs. control treatment, z = 11.94, p < 0.05; 24 h, R-saliva infiltration vs. control treatment, z = 13.29, p < 0.05; 48 h, S-saliva infiltration vs. control treatment, z = 23.15, p < 0.05; 48 h, R-saliva infiltration vs. control treatment, z = 10.95, p < 0.05). At the 72nd hour after being infiltrated by two strains of T. trifolii’s saliva, the ICS expression level of WL343 returned to a level which had no significant difference compared to the blank control.

At the 6th, 24th, 48th, and 72nd hours after being infiltrated by T. trifolii’s saliva, there was no significant difference in the expression levels of PAL (a key synthetic gene of salicylic acid) of WL343 leaves infiltrated by S-saliva and R-saliva (Figure 5f). At the 6th, 24th, and 48th hours after being infiltrated by T. trifolii’s saliva, the PAL expression level of WL343 infiltrated by S-saliva (6 h, 3.19 ± 0.36; 24 h, 5.32 ± 0.82; 48 h, 3.42 ± 0.50) and R-saliva (6 h, 2.89 ± 0.42; 24 h, 5.46 ± 0.56; 48 h, 3.91 ± 0.64) were both significantly higher than the blank control (6 h, 1.07 ± 0.06; 24 h, 1.07 ± 0.13; 48 h, 1.05 ± 0.09) (6 h, S-saliva infiltration vs. control treatment, z = 13.26, p < 0.05; 6 h, R-saliva infiltration vs. control treatment, z = 26.74, p < 0.05; 24 h, S-saliva infiltration vs. control treatment, z = 14.65, p < 0.05; 24 h, R-saliva infiltration vs. control treatment, z = 21.95, p < 0.05; 48 h, S-saliva infiltration vs. control treatment, z = 21.95, p < 0.05; 48 h, S-saliva infiltration vs. control treatment, z = 12.94, p < 0.05). At the 72nd hour after being infiltrated by two strains of T. trifolii’s saliva, the PAL expression level of WL343 returned to a level which had no significant difference compared to the blank control.