Molecular Characterization of Two Mitogen-Activated Protein Kinases: p38 MAP Kinase and Ribosomal S6 Kinase From Bombyx mori (Lepidoptera: Bombycidae), and Insight Into Their Roles in Response to BmNPV Infection

Muhammad, Azharuddin; Toufeeq, Shahzad; Yu, Hai-Zhong; Wang, Jie; Zhang, Shang-Zhi; Li, Bing; Li, Zhen; Yang, Li-Ang; Hu, Pei; Ma, Yan; Xu, Jia-Ping

The preservation of silkworm-susceptible strain P50 (LC 50 = 1.03 × 10 5 ) and -resistant strain A35 (LC 50 = 5.90 × 10 7 ) was performed in Key Laboratory of Sericulture and Anhui Agricultural University, Hefei, China. The near-isogenic line BC9 (LC 50 = 2.27 × 10 6 ) was constructed according to protocol of Wang et al. (2017) . In brief, susceptible strain P50 were crossed with resistant strain A35, and progeny was repeatedly backcrossed with the P50 for nine generations, and each progeny was screened with BmNPV. Hence, the genetic background of BC9 is much similar to the P50, but BC9 should have the resistant background derived from A35. All larvae were reared as described previously (Yu et al. 2017b) . Briefly, fresh mulberry leaves were used to feed larvae. The first-to third-instar larvae were raised in artificial climate chamber at temperature 26 ± 1°C with relative humidity of 75 ± 5% at 12 h day/night cycles, and temperature 24 ± 1°C was used for fourth-and fifth-instar larvae with the same relative humidity and photoperiod as mentioned previously.