To uncover the alleviation mechanism of quinclorac stress by salicylic acid (SA), leaf samples of Oryza sativa ssp. Japonica under quinclorac stress with and without SA pre-treatment were analyzed for transcriptional and proteomic profiling to determine the differentially expressed genes (DEGs) and proteins (DEPs), respectively. Results showed that quinclorac stress altered the expression of 2207 DEGs (1427 up-regulated, 780 down-regulated) and 147 DEPs (98 down-regulated, 49 up-regulated). These genes and proteins were enriched in glutathione (GSH) metabolism, porphyrin and chlorophyll metabolism, the biosynthesis of secondary metabolites, glyoxylate and dicarboxylate metabolism, and so on. It also influenced apetala2- ethylene-responsive element binding protein (AP2-EREBP) family, myeloblastosis (MYB) family and WRKY family transcription factors. After SA pre-treatment, 697 genes and 124 proteins were differentially expressed. Pathway analysis showed similar enrichments in GSH, glyoxylate and dicarboxylate metabolism. Transcription factors were distributed in basic helix-loop-helix (bHLH), MYB, Tify and WRKY families. Quantitative real-time PCR results revealed that quinclorac stress induced the expression of glutathion reductase (GR) genes (OsGR2, OsGR3), which was further pronounced by SA pre-treatment. Quinclorac stress further mediated the accumulation of acetaldehyde in rice, while SA enhanced the expression of OsALDH2B5 and OsALDH7 to accelerate the metabolism of herbicide quinclorac for the protection of rice. Correlation analysis between transcriptome and proteomics demonstrated that, under quinclorac stress, correlated proteins/genes were mainly involved in the inhibition of intermediate steps in the biosynthesis of chlorophyll. Other interesting proteins/genes and pathways regulated by herbicide quinclorac and modulated by SA pre-treatment were also discussed, based on the transcriptome and proteomics results.

Background: To investigate potential effects of herbicide phytotoxic on crops, a major challenge is a lack of nondestructive and rapid methods to detect plant growth that could allow characterization of herbicide-resistant plants.In such a case, hyperspectral imaging can quickly obtain the spectrum for each pixel in the image and monitor status of plants harmlessly. Method:Hyperspectral imaging covering the spectral range of 380-1030 nm was investigated to determine the herbicide toxicity in rice cultivars. Two rice cultivars, Xiushui 134 and Zhejing 88, were respectively treated with quinclorac alone and plus salicylic acid (SA) pre-treatment. After ten days of treatments, we collected hyperspectral images and physiological parameters to analyze the differences. The score images obtained were used to explore the differences among samples under diverse treatments by conducting principal component analysis on hyperspectral images. To get useful information from original data, feature extraction was also conducted by principal component analysis. In order to classify samples under diverse treatments, full-spectra-based support vector classification (SVC) models and extracted-feature-based SVC models were established. The prediction maps of samples under different treatments were constructed by applying the SVC models using extracted features on hyperspectral images, which provided direct visual information of rice growth status under herbicide stress. The physiological analysis with the changes of stress-responsive enzymes confirmed the differences of samples under different treatments. Results:The physiological analysis showed that SA alleviated the quinclorac toxicity by stimulating enzymatic activity and reducing the levels of reactive oxygen species. The score images indicated there were spectral differences among the samples under different treatments. Full-spectra-based SVC models and extracted-feature-based SVC models obtained good results for the aboveground parts, with classification accuracy over 80% in training, validation and prediction set. The SVC models for Zhejing 88 presented better results than those for Xiushui 134, revealing the different herbicide tolerance between rice cultivars. © The Author(s) 2020. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article' s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article' Conclusion:We develop a reliable and effective model using hyperspectral imaging technique which enables the evaluation and visualization of herbicide toxicity for rice. The reflectance spectra variations of rice could reveal the stress sta...

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