Transcriptomic Analysis Reveals the Effects of κ‐Carrageenan Oligosaccharides on Tobacco Mosaic Virus Resistance

Seaweed oligosaccharides exhibit multiple biological activities and act as novel plant growth regulators. Our previous research indicates that carrageenan oligosaccharides (COs) can effectively control tobacco mosaic virus (TMV) disease. To reveal the COs defence mechanisms against tobacco viruses, a transcriptomic analysis was performed to explore the potential antiviral pathways of κ‐COs. Compared with the control group, the treated groups exhibited substantial delays in disease onset, and their disease indices also markedly decreased. After TMV inoculation, compared with the control group, the defence enzyme activities, such as those of superoxide dismutase, β‐1,3‐glucanase, and peroxidase, in the treated groups significantly increased. The expression levels of key genes related to the resistance‐associated pathways, such as Nicotiana rustica ‐derived Tobacco Mosaic Virus Resistance Gene (NrCN) and Mitogen‐Activated Protein Kinase (MAPK), in the treated groups were higher than those in the untreated control group. In‐depth gene sequencing revealed that a large number of genes and their corresponding metabolic pathways in treated groups showed extremely significant variations after inoculation with TMV. This study investigated the effective influence of COs on tobacco TMV resistance and examined the effects of carrageenan oligosaccharides on the metabolism of TMV‐inoculated tobacco plants at the transcriptional level.