Abstract
BackgroundSesame (Sesamum indicum) charcoal rot, a destructive fungal disease caused by Macrophomina phaseolina (Tassi) Goid (MP), is a great threat to the yield and quality of sesame. However, there is a lack of information about the gene-for-gene relationship between sesame and MP, and the molecular mechanism behind the interaction is not yet clear. The aim of this study was to interpret the molecular mechanism of sesame resistance against MP in disease-resistant (DR) and disease-susceptible (DS) genotypes based on transcriptomics. This is the first report of the interaction between sesame and MP using this method.ResultsA set of core genes that response to MP were revealed by comparative transcriptomics and they were preferentially associated with GO terms such as ribosome-related processes, fruit ripening and regulation of jasmonic acid mediated signalling pathway. It is also exhibited that translational mechanism and transcriptional mechanism could co-activate in DR so that it can initiate the immunity to MP more rapidly. According to weighted gene co-expression network analysis (WGCNA) of differentially expressed gene sets between two genotypes, we found that leucine-rich repeat receptor-like kinase (LRR-RLK) proteins may assume an important job in sesame resistance against MP. Notably, compared with DS, most key genes were induced in DR such as pattern recognition receptors (PRRs) and resistance genes, indicating that DR initiated stronger pattern-triggered immunity (PTI) and effector-triggered immunity (ETI). Finally, the study showed that JA/ET and SA signalling pathways all play an important role in sesame resistance to MP.ConclusionsThe defence response to MP of sesame, a complex bioprocess involving many phytohormones and disease resistance-related genes, was illustrated at the transcriptional level in our investigation. The findings shed more light on further understanding of different responses to MP in resistant and susceptible sesame.
Highlights
Sesame (Sesamum indicum) charcoal rot, a destructive fungal disease caused by Macrophomina phaseolina (Tassi) Goid (MP), is a great threat to the yield and quality of sesame
We found that DS had more differently expressed genes (DEG) and Transcription factor (TF) than DR regardless of the time point post-inoculation, indicating that susceptible genotypes were more likely to be interfered by MP at the transcriptional level, which may be due to the lack of a corresponding mechanism in DS to adapt to MP stress
52 genes expressed continuously and differentially between DR and DS were screened under MP press, which were enriched in GO terms such as response to abscisic acid, cell wall, hormone-mediated signalling pathway, response to hormone, cell-cell junction, defence response and signal transduction
Summary
Sesame (Sesamum indicum) charcoal rot, a destructive fungal disease caused by Macrophomina phaseolina (Tassi) Goid (MP), is a great threat to the yield and quality of sesame. The aim of this study was to interpret the molecular mechanism of sesame resistance against MP in disease-resistant (DR) and disease-susceptible (DS) genotypes based on transcriptomics. This is the first report of the interaction between sesame and MP using this method. Plants have developed a reconnaissance mechanism to perceive and recognize these effectors, which leads to ETI Both PTI and ETI are engaged in the early defence response of plants. They perform comparative functions and early induction of defence signalling transduction and downstream molecular network responses can be observed at the physiological level, such as the burst of reactive oxygen species (ROS), the activation of mitogen activated protein kinase (MAPK) pathway and amassing of callose [4]. ROS are considered to be an essential signalling component in plant defence [7, 8]
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