Songhong Wei

Rice bakanae disease (RBD), a major threat in rice-cropping nations, can reduce rice yield and quality. As it is a seed-borne disease, effective seed detection is crucial. Loop-mediated isothermal amplification (LAMP) can rapidly and specifically amplify DNA at a constant temperature with high sensitivity. This research uses LAMP to develop rapid RBD pathogen detection systems. Primers were designed targeting the NRPS31 gene of Fusarium fujikuroi and conserved TEF1α sequences of Fusarium asiaticum, Fusarium proliferatum, and Fusarium andiyazi. These reactions at 60 °C for 60 min had a detection limit of 100 pg·μL⁻¹, and LAMP proved applicable in field trials.

Rapid and accurate detection of rice foliar diseases is essential for yield prediction and food security. This study proposes a multi-size rice leaf disease detection model, YOLOv7-tiny, for fast and accurate detection of rice leaf diseases. The MobileNetV3 lightweight network is introduced to replace the backbone network of YOLOv7-tiny, which reduces the size of the model parameters and improves the extraction capability of features of different sizes; the RCS-OSA is used to replace the original ELAN-1 module, which improves the extraction capability of interlayer features; the TSCODE detector head is designed to enhance the extraction capability of the model for small targets; and the MPDIoU loss function is used to improve the model’s convergence speed and effect. The experimental results show that the average accuracy of ofYOLOv7-TMRTM is 97.9%, and compared with the baseline YOLOv7-tiny model, the accuracy of leaf spot detection is improved for different sizes and types of small target detection results, the YOLOv7-TMRTM model improves mAP0.5 by 4.4%, recall by 4.7% and precision by 8.8% compared to YOLOv7-tiny. The comparison with Faster RCNN, SSD, YOLOv4, YOLOv5s, YOLOv8s, and other mainstream target detection models shows that this method greatly solves the field environment. The problem of small spots and fuzzy edges of photographed rice diseases provides a basis for intelligent management of diseases in the field, which in turn promotes food security in China.

Background: Rice sheath blight, which is caused by Rhizoctonia solani, is the most destructive disease affecting rice production, but the resistance mechanism to this pathogen has not been fully elucidated. Results: In this study, we selected two rice cultivars based on their resistance to the pathogen and analyzed and compared the transcriptomic profiles of two cultivars, the moderately resistant variety Gangyuan8 and the highly susceptible variety Yanfeng47, at different time points after inoculation. The comparative transcriptome profiling showed that the expression of related genes gradually increased after pathogen inoculation. The number of differentially expressed genes (DEGs) in Yanfeng47 was higher than that in Gangyuan8, and this result revealed that Yanfeng47 was more susceptible to fungal attack. At the early stage (24 and 48 h), the accumulation of resistance genes and a resistance metabolism occurred earlier in Ganguan8 than in Yanfeng47, and the resistance enrichment entries were more abundant in Ganguan8 than in Yanfeng47. Conclusions: Based on the GO and KEGG enrichment analyses at five infection stages, we concluded that phenylalanine metabolism and the jasmonic acid pathway play a crucial role in the resistance of rice to sheath blight. Through a comparative transcriptome analysis, we preliminarily analyzed the molecular mechanism responsible for resistance to sheath blight in rice, and the results lay the foundation for the development of gene mining and functional research on rice resistance to sheath blight.

Background: Rice sheath blight, caused by Rhizoctonia solani Kühn (teleomorph: Thanatephorus cucumeris), is one of the most severe diseases in rice (Oryza sativa L.) worldwide. Studies on resistance genes and resistance mechanisms of rice sheath blight have mainly focused on indica rice. Rice sheath blight is a growing threat to rice production with the increasing planting area of japonica rice in Northeast China, and it is therefore essential to explore the mechanism of sheath blight resistance in this rice subspecies. Results: In this study, RNA-seq technology was used to analyse the gene expression changes of leaf sheath at 12, 24, 36, 48, and 72 h after inoculation of the resistant cultivar ‘Shennong 9819’ and susceptible cultivar ‘Koshihikari’ with R. solani. In the early stage of R. solani infection of rice leaf sheaths, the number of differentially expressed genes (DEGs) in the inoculated leaf sheaths of resistant and susceptible cultivars showed different regularity. After inoculation, the number of DEGs in the resistant cultivar fluctuated, while the number of DEGs in the susceptible cultivar increased first and then decreased. In addition, the number of DEGs in the susceptible cultivar was always higher than that in the resistant cultivar. After inoculation with R. solani, the overall transcriptome changes corresponding to multiple biological processes, molecular functions, and cell components were observed in both resistant and susceptible cultivars. These included metabolic process, stimulus response, biological regulation, catalytic activity, binding and membrane, and they were differentially regulated. The phenylalanine metabolic pathway; tropane, piperidine, and pyridine alkaloid biosynthesis pathways; and plant hormone signal transduction were significantly enriched in the early stage of inoculation of the resistant cultivar Shennong 9819, but not in the susceptible cultivar Koshihikari. This indicates that the response of the resistant cultivar Shennong 9819 to pathogen stress was faster than that of the susceptible cultivar. The expression of plant defense response marker PR1b gene, transcription factor OsWRKY30 and OsPAL1 and OsPAL6 genes that induce plant resistance were upregulated in the resistant cultivar. These data suggest that in the early stage of rice infection by R. solani, there is a pathogen-induced defence system in resistant rice cultivars, involving the expression of PR genes, key transcription factors, PAL genes, and the enrichment of defence-related pathways. Conclusion: The transcriptome data revealed the molecular and biochemical differences between resistant and susceptible cultivars of rice after inoculation with R. solani, indicating that resistant cultivars have an immune response mechanism in the early stage of pathogen infection. Disease resistance is related to the overexpression of PR genes, key transcriptome factors, and PAL genes, which are potential targets for crop improvement.

Background: Rice sheath blight, which is caused by Rhizoctonia solani, is the most destructive disease affecting rice production, but the resistance mechanism to this pathogen has not been fully elucidated. Results: In this study, we selected two rice cultivars based on their resistance to the pathogen and analyzed and compared the transcriptomic profiles of two cultivars, the moderately resistant variety Gangyuan8 and the highly susceptible variety Yanfeng47, at different time points after inoculation. The comparative transcriptome profiling showed that the expression of related genes gradually increased after pathogen inoculation. The number of differentially expressed genes (DEGs) in Yanfeng47 was higher than that in Gangyuan8, and this result revealed that Yanfeng47 was more susceptible to fungal attack. At the early stage (24 and 48 h), the accumulation of resistance genes and a resistance metabolism occurred earlier in Ganguan8 than in Yanfeng47, and the resistance enrichment entries were more abundant in Ganguan8 than in Yanfeng47. Conclusions: Based on the GO and KEGG enrichment analyses at five infection stages, we concluded that phenylalanine metabolism and the jasmonic acid pathway play a crucial role in the resistance of rice to sheath blight. Through a comparative transcriptome analysis, we preliminarily analyzed the molecular mechanism responsible for resistance to sheath blight in rice, and the results lay the foundation for the development of gene mining and functional research on rice resistance to sheath blight.

Background: Rice sheath blight, caused by Rhizoctonia solani Kühn (teleomorph: Thanatephorus cucumeris), is one of the most severe diseases in rice (Oryza sativa L.) worldwide. Studies on resistance genes and resistance mechanisms of rice sheath blight has mainly focused on indica rice. Rice sheath blight is a growing threat to rice production with the increasing planting area of japonica rice in Northeast China, and it is therefore essential to explore the mechanism of sheath blight resistance in this rice subspecies.Results: In this study, RNA-seq technology was used to analyse the gene expression changes of leaf sheath inoculation with R. solani at 12, 24, 36, 48, and 72 h after inoculation of the resistant cultivar ‘Shennong 9819’ and susceptible cultivar ‘Yueguang’. A total of 2275 differentially expressed genes (DEGs) were identified in our study. Gene Ontology (GO) annotation and Kyoto Encyclopaedia of Genes and Genomes (KEGG) enrichment analysis of these DEGs showed that the metabolic pathways of the two rice cultivars were similar and approximately covered most of the biological processes after inoculation with R. solani. Conclusion: The main differences between the resistant and susceptible cultivars were the activity of DEGs in response to R. solani and the enrichment of metabolic pathways involved in these genes. Upon experiencing external stress, the genes in the leaf sheath of Shennong 9819 showed a fluctuating response, whereas the genes in the leaf sheath of Yueguang had a higher activity. The phenylalanine metabolism and plant hormone signal transduction play important roles in disease resistance. Their response in the leaf sheath of Shennong 9819 was faster than that of Yueguang, and they were highly enriched at 12 h after inoculation.