SWATH-MS-based quantitative proteomics reveals a uniquely intricate defense response in Cnaphalocrocis medinalis-resistant rice

Abstract

Cnaphalocrocis medinalis is a major insect pest of rice in Asia. A few defensive enzymes were reported to show higher activities in a resistant rice line (Qingliu) than in a susceptible rice line (TN1) upon leaffolder infestation. However, the overall molecular regulation of the rice defense response against leaffolder herbivory is unknown. Here, differential proteomic analysis by SWATH-MS was performed to identify differentially expressed proteins between the two rice varieties, Qingliu and TN1, at four time points of leaffolder herbivory, 0, 6, 24, and 72 h. Gene Ontology (GO) enrichment of the differentially expressed proteins indicated overrepresentation of (1) photosynthesis, (2) amino acid and derivative metabolic process, and (3) secondary metabolic process. Phenylalanine ammonia lyase and chalcone synthase, which catalyze flavonoid biosynthesis, and lipoxygenase, which catalyzes jasmonic acid biosynthesis, exhibited higher expression in Qingliu than in TN1 even before insect herbivory. Momentary activation of the light reaction and Calvin cycle was detected in Qingliu at 6 h and 24 h of insect herbivory, respectively. At 72 h of insect herbivory, amino acid biosynthesis and glutathionemediated antioxidation were activated in Qingliu. A defense response involving jasmonic acid signaling, carbon remobilization, and the production of flavonoids and glutathione could underlie the resistance of Qingliu to leaffolder. Rice production in Asia is affected by a harmful insect pest, Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae), also known as the rice leaffolder 1. Leaffolder caterpillars feed on mesophyll tissues, interfering with photosynthesis and then reducing yield 2. The affected leaf blades appear white, so heavily infested fields may have 'scorched'-looking patches. This insect herbivore can complete three life cycles during each rice cropping season in Taiwan 3,4. The application of chemical insecticides is the main method used to control pest populations in rice fields 5. However, this method of pest control is rendered less effective because the caterpillars build a feeding chamber by folding a leaf longitudinally with silk, and the chamber indirectly protects the pests from the chemical spray. When plants are infested by insect pests, they can differentiate diverse types of insects based on the insect elicitors or the nature of the damage caused by the insects 6. The plants immediately activate various defensive signaling pathways, including those associated with mitogen-activated protein kinase (MAPK) and phytohormones, such as jasmonic acid (JA), salicylic acid (SA) and ethylene (ET) 7. Chewing insects are generally known to trigger JA signaling pathways, while phloem-feeding insects trigger the SA signaling pathway 8. The JA and SA signaling pathways also participate in antagonistic crosstalk in plant-insect herbivory interactions 8. Because the signaling pathways triggered by different herbivorous insects vary, the production of downstream defensive proteins and secondary metabolites is...

Proteomics and Metabolomics Studies on the Biotic Stress Responses of Rice: an Update

“…An opposing theory states that plants suppress photosynthesis to conserve energy and reduce food supply to pathogens. Photosynthesis is enhanced by Xoo (Sana et al 2010;Li et al 2012a), insect (Liu et al 2016;Cheah et al 2020), and M. oryzae infection in the biotrophic stage (Azizi et al 2019) but suppressed by the necrotrophic fungus R. solani (Lee et al 2006;Karmakar et al 2019) and viral infection (Xu et al 2013). Therefore, photosynthetic activity varies depending on the feeding style of the pathogen, which is consistent with the response in other species (for review Chen et al 2019).…”

“…Studies on the response of rice to other insects have also revealed specific responses. The response of a resistant rice line (cultivar Qingliu) to rice leafroller (Cnaphalocrocis medinalis) involved the activation of the Calvin cycle and the light reaction of photosynthesis, followed by the biosynthesis of amino acids and other metabolites (Cheah et al 2020). Furthermore, resistance was determined by flavonoid biosynthesis at a specific rate and time.…”

“…In response to insects, two theories have been proposed to explain this phenomenon. The first notes that the intrinsic activation of photosynthesis provides organic compounds for the synthesis of defenserelated metabolites as a result of pathogen manipulation for food resources (Cheah et al 2020). An opposing theory states that plants suppress photosynthesis to conserve energy and reduce food supply to pathogens.…”

“…Resultant proteins and metabolites in response to a common biotic stressor may belong to similar pathways, which will eventually increase the efficacy of outcome to get more detailed insight into the intricate cellular activities during rice responses to that stressor. For instance, two separate proteomics and metabolomics studies on rice response to leafroller insect (Cnaphalocrocis medinalis) suggest that the JA biosynthesis pathway related proteins and metabolites are critical for resistance (Cheah et al 2020;Wang et al 2020).…”

“…Four well-characterized hormones, abscisic acid (ABA), salicylic acid (SA), jasmonates (JA), and ethylene, play a critical role in modulating cellular mechanisms and activating plant immunity (Verma et al 2016). SMs include phenolics produced via the shikimic and malonic acid pathways, terpenes via the mevalonic acid (MVA) and 2-C-methylerythritol 4-phosphate (MEP) pathways, and nitrogen-containing compounds from nitrogencontaining amino acids (Cheah et al 2020;Khare et al 2020). SMs function as antimicrobial compounds, damage-associated molecular patterns (DAMPs), and virulence factors for pathogens and are involved in callose deposition and the regulation of programmed cell death (Piasecka et al 2015;Zaynab et al 2018).…”