Institutional Publications
Permanent URI for this collectionhttps://ndkr-library.nipgr.ac.in/handle/123456789/11
Browse
6 results
Search Results
Item Targeted editing of multiple homologues of GTR1 and GTR2 genes provides the ideal low-seed, high-leaf glucosinolate oilseed mustard with uncompromised defence and yield(John Wiley & Sons, 2023) Mann, Avni; Kumari, Juhi; Kumar, Roshan; Kumar, Pawan; Pradhan, Akshay K.; Pental, Deepak; Bisht, Naveen C.Glucosinolate content in the two major oilseed Brassica crops-rapeseed and mustard has been reduced to the globally accepted Canola quality level (<30 μmoles/g of seed dry weight, DW), making the protein-rich seed meal useful as animal feed. However, the overall lower glucosinolate content in seeds as well as in the other parts of such plants renders them vulnerable to biotic challenges. We report CRISPR/Cas9-based editing of glucosinolate transporter (GTR) family genes in mustard (Brassica juncea) to develop ideal lines with the desired low seed glucosinolate content (SGC) while maintaining high glucosinolate levels in the other plant parts for uncompromised plant defence. Use of three gRNAs provided highly efficient and precise editing of four BjuGTR1 and six BjuGTR2 homologues leading to a reduction of SGC from 146.09 μmoles/g DW to as low as 6.21 μmoles/g DW. Detailed analysis of the GTR-edited lines showed higher accumulation and distributional changes of glucosinolates in the foliar parts. However, the changes did not affect the plant defence and yield parameters. When tested against the pathogen Sclerotinia sclerotiorum and generalist pest Spodoptera litura, the GTR-edited lines displayed a defence response at par or better than that of the wild-type line. The GTR-edited lines were equivalent to the wild-type line for various seed yield and seed quality traits. Our results demonstrate that simultaneous editing of multiple GTR1 and GTR2 homologues in mustard can provide the desired low-seed, high-leaf glucosinolate lines with an uncompromised defence and yield.Item Suppressing plant defence: Scavenge the ROS!(John Wiley & Sons, 2023) Prasad, Ashish; Sharma, Shambhavi; Prasad, ManojROS-mediated defence against fungal pathogens is an essential arm of plant immunity. As a counter defence, these pathogens synthesize antioxidant enzymes that scavenge the ROS produced by plants. The molecular mechanism behind the upregulation of these enzymes in fungal pathogens was unknown. A recent study by Zhang and colleagues has shed light on the mechanism, and it has been shown that deacetylation of FolSrpk1 protein on the K304 residue following oxidative stress is an important event in the signalling cascade leading to ROS detoxification in Fusarium oxysporum f. sp. lycopersici. Deacetylated FolSrpk1 moves to the nucleus where it hyperphosphorylates FolSr1, which further regulates the transcription of antioxidant enzymes (Zhang et al. 2023). This mechanism of ROS detoxification is conserved in Botrytis cinerea as well. Several other phytopathogenic fungi have a corresponding K304 site and NLS present in their Srpk1, suggesting a similar mechanism of ROS detoxification and suppression of plant defence. In this article, we have presented our views on how future studies can be synthesized based on the pathway deciphered by Zhang et al. 2023.Item Drought attenuates plant defence against bacterial pathogens by suppressing the expression of CBP60g/SARD1 during combined stress(John Wiley & Sons, 2022) Choudhary, Aanchal; Senthil-Kumar, MuthappaIn nature, plants are frequently exposed to drought and bacterial pathogens simultaneously. However, information on how the drought and defence pathways interact and orchestrate global transcriptional regulation is limited. Here, we show that moderate drought stress enhances the susceptibility of Arabidopsis thaliana to Pseudomonas syringae pv. tomato DC3000. Using transcriptome meta-analysis, we found that drought and bacterial stress antagonistically modulate a large set of genes predominantly involved in salicylic acid (SA) and abscisic acid (ABA) signalling networks. We identified that the levels of SA and ABA are dynamically regulated during the course of stress. Importantly, under combined stress, drought through the ABA pathway downregulates the induction of CALMODULIN-BINDING PROTEIN 60g (CBP60g) and SYSTEMIC ACQUIRED RESISTANCE DEFICIENT 1 (SARD1), two transcription factors crucial for SA production upon bacterial infection. We also identified an important role of NPR1-LIKE PROTEIN 3 and 4 (NPR3/4) transcriptional repressors in the drought-mediated negative regulation of CBP60g/SARD1 expression. Using a genetic approach, we show that CBP60g/SARD1 expression is the key determinant of plant defence against bacterial pathogens under combined stress. Thus, these transcription factors act as critical nodes for the crosstalk between drought and bacterial stress signalling under combined stress in plants.Item Extra-large G-proteins influence plant response to Sclerotinia sclerotiorum by regulating glucosinolate metabolism in Brassica juncea(John Wiley & Sons, 2021) Tiwari, Ruchi; Kaur, Jagreet; Bisht, Naveen C.Heterotrimeric G-proteins are one of the highly conserved signal transducers across phyla. Despite the obvious importance of G-proteins in controlling various plant growth and environmental responses, there is no information describing the regulatory complexity of G-protein networks during pathogen response in a polyploid crop. Here, we investigated the role of extra-large G-proteins (XLGs) in the oilseed crop Brassica juncea, which has inherent susceptibility to the necrotrophic fungal pathogen Sclerotinia sclerotiorum. The allotetraploid B. juncea genome contains multiple homologs of three XLG genes (two BjuXLG1, five BjuXLG2, and three BjuXLG3), sharing a high level of sequence identity, gene structure organization, and phylogenetic relationship with the progenitors’ orthologs. Quantitative reverse transcription PCR analysis revealed that BjuXLGs have retained distinct expression patterns across plant developmental stages and on S. sclerotiorum infection. To determine the role of BjuXLG genes in the B. juncea defence response against S. sclerotiorum, RNAi-based suppression was performed. Disease progression analysis showed more rapid lesion expansion and fungal accumulation in BjuXLG-RNAi lines compared to the vector control plants, wherein suppression of BjuXLG3 homologs displayed more compromised defence response at the later time point. Knocking down BjuXLGs caused impairment of the host resistance mechanism to S. sclerotiorum, as indicated by reduced expression of defence marker genes PDF1.2 and WRKY33 on pathogen infection. Furthermore, BjuXLG-RNAi lines showed reduced accumulation of leaf glucosinolates on S. sclerotiorum infection, wherein aliphatic glucosinolates were significantly compromised. Overall, our data suggest that B. juncea XLG genes are important signalling nodes modulating the host defence pathways in response to this necrotrophic pathogen.Item Moving nitrogen to the centre of plant defence against pathogens(Oxford University Press, 2017) Mur, Luis A.J.; Simpson, Catherine; Kumari, Aprajita; Gupta, Alok Kumar; Gupta, Kapuganti JagadisBackground Plants require nitrogen (N) for growth, development and defence against abiotic and biotic stresses. The extensive use of artificial N fertilizers has played an important role in the Green Revolution. N assimilation can involve a reductase series (NO–3→ NO–2 → NH+4) followed by transamination to form amino acids. Given its widespread use, the agricultural impact of N nutrition on disease development has been extensively examined. Scope: When a pathogen first comes into contact with a host, it is usually nutrient starved such that rapid assimilation of host nutrients is essential for successful pathogenesis. Equally, the host may reallocate its nutrients to defence responses or away from the site of attempted infection. Exogenous application of N fertilizer can, therefore, shift the balance in favour of the host or pathogen. In line with this, increasing N has been reported either to increase or to decrease plant resistance to pathogens, which reflects differences in the infection strategies of discrete pathogens. Beyond considering only N content, the use of NO-3 or NH+4 fertilizers affects the outcome of plant–pathogen interactions. NO-3 feeding augments hypersensitive response- (HR) mediated resistance, while ammonium nutrition can compromise defence. Metabolically, NO–3 enhances production of polyamines such as spermine and spermidine, which are established defence signals, with NH+4 nutrition leading to increased γ-aminobutyric acid (GABA) levels which may be a nutrient source for the pathogen. Within the defensive N economy, the roles of nitric oxide must also be considered. This is mostly generated from NO–2 by nitrate reductase and is elicited by both pathogen-associated microbial patterns and gene-for-gene-mediated defences. Nitric oxide (NO) production and associated defences are therefore NO-3 dependent and are compromised by NH+4. Conclusion:This review demonstrates how N content and form plays an essential role in defensive primary and secondary metabolism and NO-mediated events.Item Systemic cytosolic Ca2+ elevation is activated upon wounding and herbivory in Arabidopsis(John Wiley & Sons, 2015) Kiep, Victoria; Vadassery, Jyothilakshmi; Lattke, Justus; Maaß, Jan-Peter; Boland, Wilhelm; Peiter, Edgar; Mithöfer, AxelCalcium ion (Ca2+) signalling triggered by insect herbivory is an intricate network with multiple components, involving positive and negative regulators. Real-time, noninvasive imaging of entire Arabidopsis thaliana rosettes was employed to monitor cytosolic free calcium ([Ca2+]cyt) elevations in local and systemic leaves in response to wounding and Spodoptera littoralis feeding. Luminescence emitted by the cytosol-localized Ca2+ reporter aequorin was imaged using a high-resolution photon-counting camera system. Spodoptera littoralis feeding on Arabidopsis induced both local and systemic [Ca2+]cyt elevations. Systemic [Ca2+]cyt signals were found predominantly in adjacent leaves with direct vascular connections to the treated leaf and appeared with a delay of 1 to 2 min. Simulated herbivory by wounding always induced a local [Ca2+]cyt response, but a systemic one only when the midrib was wounded. This systemic [Ca2+]cyt response was suppressed by the presence of insect-derived oral secretions as well as in a mutant of the vacuolar cation channel, Two Pore Channel 1 (TPC1). Our results provide evidence that in Arabidopsis insect herbivory induces both local and systemic [Ca2+]cyt signals that distribute within the vascular system. The systemic [Ca2+]cyt signal could play an important signalling role in systemic plant defence.