Identification and characterization of Locusta migratoria microRNAs response to Metarhizium robertsii infection through high-throughput sequencing

a high-throughput Illumina/Solexa sequencing was conducted, 478262, 702593, 835394 and 894277 unique sRNAs was discovered from four periods of M. robertsii infection, uninfected (0h), infected for 12h, 24h and 36h. Then, 7, 7, 6 and 7 known pre-miRNAs were obtained, and 33, 58, 54 and 52 candidate novel miRNAs was detected in four periods. Further analysis showed that 24 of those candidate novel miRNAs were matched to other known insect miRNAs, while 36 of those miRNAs lacked sequence homologues of insect organisms. Locusts were randomly selected as 3rd instar and injected 5μl of 2ｘ107 spores/ml conidia suspensions into pronotum for each individual. Abdomens from uninfected locusts (0h) and infected 12h、24h and 36h locusts were collected respectively, flash frozen in liquid nitrogen, and stored at -80℃ until RNA extraction. Each sample contained three replications.