Xam challenges cassava Protein Interaction Network reveals key regulatory elements of immunity processes

To gain insights on the kinetics of cassava gene expression in response to Xam an RNAseq analysis was performed. Cassava stem cuttings from TMS30572 variety were grown under greenhouse conditions and inoculated with Xam strain Xam681 by puncturing at the third internode from the apical region using sterile tips. The inoculum was adjusted to an OD600nm of 0.2. The control plants were inoculated with 10 nm of MgCl2 meanwhile treatment plants with 10 ul of the inoculum. In addition, to assay the inoculation puncturing effect, not inoculated plants were grown under the same conditions. Three biological replicates were performed for each treatment. The stem samples were collected at 1, 3 and 5 days post inoculation (dpi). Total RNA was isolated using Trizol protocol (Invitrogen) following manufacturer''s instructions. Concentration and purity were evaluated by Agilent 2100 (Agilent Technologies, Santa Clara, USA). The paired-end libraries were construct using 3 ug of total RNA and size selection of 101 pb according to Illumina instructions. The libraries were sequenced by Illumina HiSeqTM 2000 platform. In total 98 downregulated genes and 72 upregulated genes comparing day3 and day5 of inoculation with the non treated plants were identified and used to construct a cassava coexpression network.