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Expression analysis of marker genes for JA (A,B), ABA (C,D), IAA (E,F), and GA (G,H) in the sixth leaf of mock control (CW, CB, and CS), blast-infected (BW, BB, and BS), and cutting off blast-infected leaf blades (BcW, BcB, and BcS). Rice seedlings at four-leaf stage were blast-inoculated, and half of them were subjected to cutting off the inoculated fourth leaf blades at 2-dpi. Whole sixth leaf from every treatment was collected at 3-dpi (CW, BW, and BcW), and leaf blades (CB, BB, and BcB) and leaf sheathes (CS, BS, and BcS) separately at 6-dpi. Values are the means ± standard errors. Different letters above bars indicate a significant difference (P < 0.05) based on Duncan’s test; (w): for whole leaves, (b): for leaf blades, (s): for leaf sheaths.
Source publication
In response to pathogen attack, plants prioritize defense reactions generally at the expense of plant growth. In this work, we report that changes in phytohormone signaling pathways are associated with the stunted plant growth caused by blast disease in rice seedlings. Infection of rice seedlings with blast fungus Magnaporthe oryzae (race 007.0) at...
Citations
... 16,21 Severe infections have the potential to kill off entire plant tissues, decreasing their ability to photosynthesize and interfering with vital physiological functions. 22,23 The result is reduced grain filling, stunted growth, and declined overall productivity in the infected plants. A rice blast can have a severe economic impact due to the ability to spread quickly, particularly in favorable environmental conditions. ...
One of the most destructive diseases affecting rice is rice blast, which is brought on by the rice blast fungus Magnaporthe oryzae. The preventive measures, however, are not well established. To effectively reduce the negative effects of rice blasts on crop yields, it is imperative to comprehend the dynamic interactions between pathogen resistance and patterns of host carbon allocation. This review explores the relationship between variations in carbon allocation and rice plants’ ability to withstand the damaging effects of M. oryzae. The review highlights potential strategies for altering host carbon allocation including transgenic, selective breeding, crop rotation, and nutrient management practices as a promising avenue for enhancing rice blast resistance. This study advances our knowledge of the interaction between plants’ carbon allocation and M. oryzae resistance and provides stakeholders and farmers with practical guidance on mitigating the adverse effects of the rice blast globally. This information may be used in the future to create varieties that are resistant to M. oryzae.
... Total RNA was extracted with TRIzol reagent (TaKaRa Bio Tokyo, Japan) and first-strand cDNA was synthesized using M-MLV reverse transcriptase (Thermo, Carlsbad, CA, USA) according to the manufacturer's protocols. Quantitative real-time PCR (qRT-PCR) was performed to determine the transcriptional expression of genes, including two ABA-response genes, SalT [24,63,64] and OsWsi18 [24,64,65], and eight ROS-scavenging genes, OsCATA , OsCATB, OsAPX6, OsAPX7, OsCu/Zn-SOD, OsFe-SOD, Putative copper/zinc superoxide dismutase and SODCc2 [6]. Gene-specific primers were designed using Primer 5.0 software (Table S1). ...
... Total RNA was extracted with TRIzol reagent (TaKaRa Bio Tokyo, Japan) and first-strand cDNA was synthesized using M-MLV reverse transcriptase (Thermo, Carlsbad, CA, USA) according to the manufacturer's protocols. Quantitative real-time PCR (qRT-PCR) was performed to determine the transcriptional expression of genes, including two ABA-response genes, SalT [24,63,64] and OsWsi18 [24,64,65], and eight ROS-scavenging genes, OsCATA , OsCATB, OsAPX6, OsAPX7, OsCu/Zn-SOD, OsFe-SOD, Putative copper/zinc superoxide dismutase and SODCc2 [6]. Gene-specific primers were designed using Primer 5.0 software (Table S1). ...
Background
Heat stress is a major restrictive factor that causes yield loss in rice. We previously reported the priming effect of abscisic acid (ABA) on rice for enhanced thermotolerance at the germination, seedling and heading stages. In the present study, we aimed to understand the priming effect and mechanism of ABA on grain filling capacity in rice under heat stress.
Results
Rice plants were pretreated with distilled water, 50 μM ABA and 10 μM fluridone by leaf spraying at 8 d or 15 d after initial heading (AIH) stage and then were subjected to heat stress conditions of 38 °C day/30 °C night for 7 days, respectively. Exogenous ABA pretreatment significantly super-activated the ABA signaling pathway and improved the SOD, POD, CAT and APX enzyme activity levels, as well as upregulated the ROS-scavenging genes; and decreased the heat stress-induced ROS content (O2– and H2O2) by 15.0–25.5% in rice grain under heat stress. ABA pretreatment also increased starch synthetase activities in rice grain under heat stress. Furthermore, ABA pretreatment significantly improved yield component indices and grain yield by 14.4–16.5% under heat stress. ABA pretreatment improved the milling quality and the quality of appearance and decreased the incidence of chalky kernels and chalkiness in rice grain and improved the rice grain cooking quality by improving starch content and gel consistence and decreasing the amylose percentage under heat stress. The application of paraquat caused overaccumulation of ROS, decreased starch synthetase activities and ultimately decreased starch content and grain yield. Exogenous antioxidants decreased ROS overaccumulation and increased starch content and grain yield under heat stress.
Conclusion
Taken together, these results suggest that exogenous ABA has a potential priming effect for enhancing rice grain filling capacity under heat stress at grain filling stage mainly by inhibiting ROS overaccumulation and improving starch synthetase activities in rice grain.
... In addition, there are some indications that ABA biosynthesis could be slightly enhanced by the overexpression of OsNCED2 and OsNCED3 under stress conditions ( Figure 6); these genes encode key enzymes in the ABA biosynthetic pathway of rice that regulate various processes, such as seed dormancy, plant growth, stress tolerance, and leaf senescence [66]. OsSalT and OsWsi18, two ABA-responsive genes [67], were significantly induced by ABA pretreatment in this study. The upregulation of these ABA-response genes may enhance ABA signaling, resulting in an effect similar to that of exogenous ABA pretreatment under saline and alkaline stresses. ...
The plant hormone abscisic acid (ABA) regulates the plant response to environmental stress; therefore, ABA priming is an effective strategy for enhancing stress tolerance in rice. In this study, we investigated the priming effects of 1 and 5 µM ABA on the biochemical and physiological traits associated with seedling growth performance in two rice cultivars exposed to saline (100 mM NaCl) and alkaline (15 mM Na2CO3) stress via root drenching. ABA pretreatment effectively reduced damage in rice seedlings by mitigating the increases in Na+/K+ ratio, membrane injury, contents of Na+, malondialdehyde, hydrogen peroxide, and superoxide anion radical, and prevented reductions in K+ and total chlorophyll contents, and ROS-related enzyme activities in both cultivars under saline and alkaline stresses. Rice seedlings with ABA pretreatment under alkaline stress had a stronger ability to maintain ion homeostasis, eliminate ROS, and induce changes in endogenous ABA levels via the upregulation of OsHKT1;5, OsSOS1, OsNHX5, OsPOX1, OsCATA, OsNCED3, OsSalT, and OsWsi18 and downregulation of OsRbohA than under saline stress. The saline–alkaline (SA)-sensitive cultivar demonstrated greater sensitivity to the priming effect of ABA than that of the SA-tolerant cultivar under both stress conditions. These findings have implications for rice adaptation to SA soils.
... The activity was Pst but improved both defense and growth under GABA+Pst. Jiang et al. (2017) reported that in response to pathogen attacks, plants prioritize defense reactions generally at the expense of plant growth. Phytohormone signaling pathways are associated with the stunted plant growth caused by blast disease in rice seedlings (Jiang et al., 2017). ...
... Jiang et al. (2017) reported that in response to pathogen attacks, plants prioritize defense reactions generally at the expense of plant growth. Phytohormone signaling pathways are associated with the stunted plant growth caused by blast disease in rice seedlings (Jiang et al., 2017). Like other foliar diseases, yield losses under stripe rust can be due loss of photosynthesis thus reduced carbohydrate availability for grain filling (Devdas et al., 2014;Chen et al., 2015). ...
Aim: The present study was undertaken to screen wheat cultivars for resistance against stripe rust and the improvement of resistance by exogenous gamma-aminobutyric acid (GABA) under field conditions and studying two contrasting cultivars for antioxidant related defense activities at 1, 2 and 4 d of GABA, Puccinia striiformis f. sp. tritici (Pst) and GABA+Pst treatments given to one-month-old seedlings. Methodology: Wheat cultivars (PBW723, PBW725, PBW677, PBW550, PBW343, PBW621, HD2967) were grown and exposed to Puccinia striiformis f. sp. tritici (Pst) and GABA+Pst in fields and studied for yield parameters. Subsequently, two cultivars found varying in resistance (PBW725 and HD2967) were analyzed for antioxidant enzymes in leaves and roots at 1, 2, and 4 day of GABA, Pst, and GABA+Pst and water as control given to 30 days old seedlings in the greenhouse. Results: Field analysis found that the most resistant cultivar PBW725 reduced vegetative growth but not yield compared to other resistant cultivars (PBW723 and PBW677) under Pst and improved both growth and yield under GABA+Pst. GABA+Pst improved yield parameters in other cultivars also. In defense analysis, superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione-S-transferase (GST) increased in the leaves of PBW725 while only APX increased in HD2967 at 1 d of Pst. In roots also, SOD and GST increased 2-fold in PBW725 while only GST increased 1.3-fold in HD2967 at 1 d of Pst. There was persistence of catalase (CAT), monodehydroascorbate reductase (MDHAR), and dehydroascorbate reductase (DHAR) during Pst in the leaves of PBW 725 while CAT decreased at 4 d in HD2967. In roots also, CAT and MDHAR increased at 4 days of Pstin PBW725 while DHAR decreased in HD2967. Under GABA, cultivar differences were not significant. GABA+Pst improved deficient antioxidant enzymes in HD2967. Interpretation: Energy conservation and timely regulation of antioxidant enzymes during infection was utilized by PBW725 against stripe rust. GABA deficiency can be a reason for poor regulation of antioxidants in HD2967 under Pst. GABA application improved resistance against stripe rust in wheat. Key words: Antioxidant, Ascorbate, Gamma-aminobutyric acid, Glutathione, Stripe rust, Triticum aestivum
... Secondly, M. oryzae modifies the rice active JA molecule to an inactive 12-OH JA, thereby denting the host-resistance response [192]. In rice, infection with M. oryzae represses the auxin signaling pathway in the distal healthy leaves by repressing the auxinresponsive genes such as ARF1 and IAA9 and thereby inducing systemic acquired resistance (SAR) against this pathogen [193]. On the contrary, the accumulation of auxins leads to rice susceptibility to M. oryzae [194]. ...
... Secondly, M. oryzae modifies the rice active JA molecule to an inactive 12-OH JA, thereby denting the host-resistance response [192]. In rice, infection with M. oryzae represses the auxin signaling pathway in the distal healthy leaves by repressing the auxin-responsive genes such as ARF1 and IAA9 and thereby inducing systemic acquired resistance (SAR) against this pathogen [193]. On the contrary, the accumulation of auxins leads to rice susceptibility to M. oryzae [194]. ...
... Unlike auxins and CKs, ABA has an antagonistic effect on disease resistance through the suppression of SAR mediated by SA, JA, and ET signaling pathways [196]. It was observed that a reduction or disruption of ABA signaling enhanced blast resistance, whereas exogenous ABA application enhanced the susceptibility towards M. oryzae in rice [193,197]. A schematic diagram depicting the role of reported phytohormones in rice blast disease response is presented in Figure 4. [193,197]. ...
Rice is a global food grain crop for more than one-third of the human population and a source for food and nutritional security. Rice production is subjected to various stresses; blast disease caused by Magnaporthe oryzae is one of the major biotic stresses that has the potential to destroy total crop under severe conditions. In the present review, we discuss the importance of rice and blast disease in the present and future global context, genomics and molecular biology of blast pathogen and rice, and the molecular interplay between rice–M. oryzae interaction governed by different gene interaction models. We also elaborated in detail on M. oryzae effector and Avr genes, and the role of noncoding RNAs in disease development. Further, rice blast resistance QTLs; resistance (R) genes; and alleles identified, cloned, and characterized are discussed. We also discuss the utilization of QTLs and R genes for blast resistance through conventional breeding and transgenic approaches. Finally, we review the demonstrated examples and potential applications of the latest genome-editing tools in understanding and managing blast disease in rice.
... Various suitable nutrient-rich niches on/or inside roots attract a great diversity of microorganisms, including phytopathogens. Biocontrol PGPB are aggressive root colonizers and play an important role in the biological control of plant diseases caused by soil-borne fungal pathogens (Yu et al., 2017). Another mechanism of biological control by PGPR is production of allelochemicals like (i) Fe (III)-chelating siderophores, which deprive pathogenic fungi of Fe since the fungal siderophores have lower affinity to Fe compared to bacterial siderophores; (ii) production of antibiotics such as amphisin, 2,4-diacetylphloroglucinol (DAPG), rhizoxin, oomycin A, phenazines, tensin, pyoluteorin, pyrrolnitrin, tensin, tropolone, oligomycin A, kanosamine, zwittermicin A, xanthobaccin, viscosinamide, and cyclic lipopeptides; (iii) biocidal volatiles like HCN and ammonia (NH3); (iv) lytic enzymes such as chitinase, which inhibits spore germination and germtube elongation, laminarinase, which digests and lyses mycelia of some fungi, b-1,3-glucanase, which lyses fungal cell walls of some fungi, glucanases, cellulases, and detoxification enzymes. ...
... Plant growth is controlled by phytohormones like auxin and ethylene, which have a positive effect on plants. Phytohormones are messengers which are chemicals that play an important function in improving the plant development, seed germination, and flowering time in plants (Jiang et al. 2017). More so, root exudates secreted by plants in the rhizosphere help to modulate the microflora around plant roots and construct a potential environment for the synthesis of indole-3-acetic acid (IAA) by the beneficial microorganisms in the rhizosphere. ...
Citation: Fasusi O.A., Babalola O.O. (2021): The multifaceted plant-beneficial rhizobacteria toward agricultural sustainability. Plant Protect. Sci., 57: 95-111. Abstract: Agricultural practices depend mainly on the use of chemical fertilisers, pesticides, and herbicides which have caused serious health hazards and have also contributed to the pollution of the environment at large. The application of plant-beneficial rhizobacteria in agrarian practices has become paramount in increasing soil fertility, promoting plant growth, ensuring food safety, and increasing crop production to ensure sustainable agriculture. Beneficial rhizobacteria are soil microorganisms that are eco-friendly and serve as a modern method of improving the plant yield, protecting the plant and soil fertility that pose no harm to humans and the environment. This eco-friendly approach requires the application of beneficial rhizobacteria with plant growth-promoting traits that can improve the nutrient uptake, enhance the resistance of plants to abiotic and biotic stress, protect plants against pathogenic microorganisms and promote plant growth and yield. This review article has highlighted the multitasking roles that beneficial rhizobacteria employ in promoting plant growth, food production, bioremediation, providing defence to plants, and maintaining soil fertility. The knowledge acquired from this review will help in understanding the bases and importance of plant-beneficial rhizobacteria in ensuring agricultural sustainability and as an alternative to the use of agrochemicals.
... signaling network related to growth and development, phytohormones can also trigger plant defense in response to pathogen infection or insect herbivory via stimulating the expressions of defense-related genes (De Vleesschauwer et al. 2014;Peng et al. 2012). Jasmonic acid (JA) and its precursors and derivatives, referred as jasmonates (JAs), are well-recognized lipidic plant hormones synthesized from linolenic acid in the chloroplast membrane, which have been demonstrated participating in diverse physiological and stress-related processes, including elicitation (De Vleesschauwer et al. 2014;Gundlach et al. 1992;Jiang et al. 2017;Kim et al. 2009). Treatment with exogenous methyl jasmonate in barley was reported to improve the resistance towards the powdery mildew (Walters et al. 2002). ...
Rice blast disease is one of the most common rice diseases worldwide. It is essential to improve disease resistance through environment-friendly methods, while maintaining yield and quality parameters. In this study, jasmonic acid (JA), a plant hormone with anti-fungal activity, was obtained, at both low (100 μmol/L) and high (400 μmol/L) concentrations in rice leaves, before, during, and after infection, respectively. JA could inhibit germination and appressorium formation of rice blast spores in a dose-dependent manner. A total of 400-μmol/L JA treatment significantly enhanced cell viability and endogenous JA level in rice leaves. Furthermore, rice leaves inoculated with Magnaporthe oryzae and sprayed with JA 72 h post-inoculation showed the maximum symptom relief and the highest endogenous JA production among all treatment approaches. The expressions of defense-related genes, OsPR10a and OsAOS2, were highly up-regulated in response to JA, whereas OsEDS1 was down-regulated. Hence, we revealed that exogenous JA could activate JA signaling to effectively control the symptoms of rice blast.
... Cellulose synthase gene (LOC_Os03g26044) was prominently associated with SNP (S3_14933779) and reported to be involved in blast resistance mechanism as they are down regulated in cell wall tissue expression experiments. Cellulose synthase genes OsCESA5 and OsCESA6 were severely affected during rice blast fungus infection and were down regulated (Jiang et al. 2017). ...
... To our surprise, more than half of the genes were downregulated upon M. oryzae infection in IRBLb-B. There may be some antagonism between growth and disease resistance, and plants that exhibit better resistance often sacrifice certain growth (Jiang et al. 2017). ...
... After knock out the gene LOX3 which is significant induced by rice blast in IRBLb-B, we found that lox3#KO was more susceptible to rice blast, which indicated that the resistance of IRBLb-B required the participation of JA-related genes. More recently, other plant hormones, including ABA and auxin have also emerged as crucial regulator of plant-pathogen interactions (Anderson et al. 2004;Jiang et al. 2017; Jiang et al. Yazawa et al. 2012). ...
Rice blast, caused by the fungus Magnaporthe oryzae, is a highly damaging disease. Introducing genes, which confer a broad spectrum resistance to the disease, such as Pib, makes an important contribution to protecting rice production. However, little is known regarding the mechanistic basis of the products of such genes. In this study, transcriptome of the cultivar Lijiangxintuanheigu (LTH) and its monogenic IRBLb-B which harbors Pib treated with M. oryzae were compared. Among the many genes responding transcriptionally to infection were some encoding products involved in the metabolism of ROS (reactive oxygen species), in jasmonate (JA) metabolism, and WRKY transcription factors, receptor kinases, and resistance response signal modulation. The down-regulation of genes encoding peroxiredoxin and glutathione S transferases implied that the redox homeostasis is essential for the expression of Pib-mediated resistance. The up-regulation of seven disease resistance-related genes, including three encoding a NBS-LRR protein, indicated that disease resistance-related genes are likely tend to support the expression of Pib resistance. These data revealed that potential candidate genes and transcriptional reprogramming were involved in Pib-mediated resistance mechanisms.
