Abstract
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.
Highlights
Rice (Oryza sativa L.) is one of the most important cereal crops in China, grown over an area of 30.2 million hectares and producing 208.2 million tons of rice [1]
The Q group of plants was treated with herbicide quinclorac (0.1 mM), whereas Q + salicylic acid (SA) treatment represents the pre-treatment of rice plants with SA (10 mg/L) for two days prior to the application of herbicide quinclorac (0.1 mM)
We have explored and analyzed the transcriptome and proteomics of Oryza sativa ssp. japonica to identify and annotate transcripts and proteins associated with quinclorac toxicity and its subsequent alleviation by the exogenous application of SA
Summary
Rice (Oryza sativa L.) is one of the most important cereal crops in China, grown over an area of 30.2 million hectares and producing 208.2 million tons of rice [1]. The most effective, prompt and economic method for the control of weeds is related to the use of chemicals, such as the application of herbicides. Synthetic herbicides have been used in agriculture on a global scale for about 70 years. Quinclorac (3,7-dichloro-8-quinolinecarboxylic acid) belonging to the quinoline carboxylic acid type is one of most effective synthetic herbicides, which can kill Echinochloa crus-galli (barnyard grass) and other rice weeds [3]. In China, this herbicide has been used to control barnyard grass in rice fields for almost 30 years; it has evolved a resistance to quinclorac [4]. Excessive or inappropriate herbicide use to control resistant weeds can cause phytotoxicity, which may jeopardize the crop at an early stage. The concept of enhancing crop tolerance to herbicides with the use of chemical treatments was proposed in the late 1940s [5]
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