Early transcriptional response of seedling roots to Ralstonia solanacearum in tobacco ( Nicotiana tabacum L.)

Bacterial wilt (BW) caused by Ralstonia solanacearum ( Ras ) is a very destructive disease in solanaceous crops. The molecular mechanism underlying BW resistance in solanaceous plants is still unclear. Using RNA sequencing, we investigated the transcriptional response in the seedling roots of a BW-resistant cultivar D101 and a BW-susceptible cultivar Changbohuang (CBH) of tobacco at 3 h after inoculation with Ras . In total, 158 and 835 differentially expressed genes (DEGs) were detected in D101 and CBH, respectively. Only 41 DEGs were in common between the two cultivars. The number of DEGs in D101 was much smaller than that in CBH, suggesting that D101 was less affected by the inoculation than CBH because of its higher resistance, which could be expressed at the early stages of Ras infection. Transcriptome analysis revealed that in D101 two sets of upregulated genes were significantly enriched in two corresponding groups of gene ontology terms regarding glutathione and flavonoids metabolisms, respectively, suggesting that glutathione and flavonoids are probably two types of main substances conferring the early resistance against Ras infection in tobacco root. Our findings provide a valuable clue to deeply investigate the molecular mechanism of BW resistance in tobacco and solanaceous plants.