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Author: search.filters.author.Loake, Gary J.Subject: search.filters.subject.nitric oxide

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    New insights into nitric oxide biosynthesis underpin lateral root development
    (Elsevier B.V., 2024) Gupta, Kapuganti Jagadis; Yadav, Nidhi; Kumari, Aprajita; Loake, Gary J.
    In recent years, nitric oxide (NO) has emerged as a key redox signaling molecule in plants functioning in the regulation of key developmental programs and the orchestration of responses to a plethora of environmental cues (Kolbert et al., 2019). The predominant route for the transfer of NO bioactivity is through S-nitrosylation, the addition of an NO moiety to a protein cysteine thiol to form an S-nitrosothiol (Yun et al., 2011). Specificity for this process is established by the structural constraints imposed by tertiary protein structure in gating access to given cysteine redox switches and associated proteins that can either facilitate the addition or removal of the NO moiety at these residues (Umbreen et al., 2018).
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    The emerging roles of nitric oxide and its associated scavengers-phytoglobins-in plant symbiotic interactions
    (Oxford University Press, 2024) Pathak, Pradeep Kumar; Yadav, Nidhi; Kaladhar, Vemula Chandra; Jaiswal, Rekha; Kumari, Aprajita; Igamberdiev, Abir U.; Loake, Gary J.; Gupta, Kapuganti Jagadis
    A key feature in the establishment of symbiosis between plants and microbes is the maintenance of the balance between the production of the small redox-related molecule, nitric oxide (NO), and its cognate scavenging pathways. During the establishment of symbiosis, a transition from a normoxic to a microoxic environment often takes place, triggering the production of NO from nitrite via a reductive production pathway. Plant hemoglobins [phytoglobins (Phytogbs)] are a central tenant of NO scavenging, with NO homeostasis maintained via the Phytogb–NO cycle. While the first plant hemoglobin (leghemoglobin), associated with the symbiotic relationship between leguminous plants and bacterial Rhizobium species, was discovered in 1939, most other plant hemoglobins, identified only in the 1990s, were considered as non-symbiotic. From recent studies, it is becoming evident that the role of Phytogbs1 in the establishment and maintenance of plant–bacterial and plant–fungal symbiosis is also essential in roots. Consequently, the division of plant hemoglobins into symbiotic and non-symbiotic groups becomes less justified. While the main function of Phytogbs1 is related to the regulation of NO levels, participation of these proteins in the establishment of symbiotic relationships between plants and microorganisms represents another important dimension among the other processes in which these key redox-regulatory proteins play a central role.
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    Novel and conserved functions of S-nitrosoglutathione reductase in tomato
    (Oxford University Press, 2019) Hussain, Adil; Yun, Byung-Wook; Kim, Ji Hyun; Gupta, Kapuganti Jagadis; Hyung, Nam-In; Loake, Gary J.
    Nitric oxide (NO) is emerging as a key signalling molecule in plants. The chief mechanism for the transfer of NO bioactivity is thought to be S-nitrosylation, the addition of an NO moiety to a protein cysteine thiol to form an S-nitrosothiol (SNO). The enzyme S-nitrosoglutathione reductase (GSNOR) indirectly controls the total levels of cellular S-nitrosylation, by depleting S-nitrosoglutathione (GSNO), the major cellular NO donor. Here we show that depletion of GSNOR function impacts tomato (Solanum lycopersicum. L) fruit development. Thus, reduction of GSNOR expression through RNAi modulated both fruit formation and yield, establishing a novel function for GSNOR. Further, depletion of S. lycopersicum GSNOR (SlGSNOR) additionally impacted a number of other developmental processes, including seed development, which also has not been previously linked with GSNOR activity. In contrast to Arabidopsis, depletion of GSNOR function did not influence root development. Further, reduction of GSNOR transcript abundance compromised plant immunity. Surprisingly, this was in contrast to previous data in Arabidopsis that reported that reducing Arabidopsis thaliana GSNOR (AtGSNOR) expression by antisense technology increased disease resistance. We also show that increased SlGSNOR expression enhanced pathogen protection, uncovering a potential strategy to enhance disease resistance in crop plants. Collectively, our findings reveal, at the genetic level, that some but not all GSNOR activities are conserved outside the Arabidopsis reference system. Thus, manipulating the extent of GSNOR expression may control important agricultural traits in tomato and possibly other crop plants.
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    Recommendations on terminology and experimental best practice associated with plant nitric oxide research
    (John Wiley & Sons, 2020) Gupta, Kapuganti Jagadis; Hancock, John T.; Petrivalsky, Marek; Kolbert, Zsuzsanna; Lindermayr, Christian; Durner, Jorg; Barroso, Juan B.; Palma, José M.; Brouquisse, Renaud; Wendehenne, David; Corpas, Francisco J.; Loake, Gary J.
    Nitric oxide (NO) emerged as a key signal molecule in plants. During the last two decades impressive progress has been made in plant NO research. This small, redox‐active molecule is now known to play an important role in plant immunity, stress responses, environmental interactions, plant growth and development. To more accurately and robustly establish the full spectrum of NO bioactivity in plants, it will be essential to apply methodological best practice. In addition, there are some instances of conflicting nomenclature within the field, which would benefit from standardisation. In this context, we attempt to provide some helpful guidance for best practice associated with NO research and also suggestions for the cognate terminology.
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    Nitric oxide accelerates germination via the regulation of respiration in chickpea
    (Oxford University Press, 2019) Pandey, Sonika; Kumari, Aprajita; Shree, Manu; Kumar, Vinod; Singh, Pooja; Bharadwaj, Chellapilla; Loake, Gary J.; Parida, Swarup K.; Masakapalli, Shyam Kumar; Gupta, Kapuganti Jagadis
    Seed germination is crucial for the plant life cycle. We investigated the role of nitric oxide (NO) in two chickpea varieties that differ in germination capacity: Kabuli, which has a low rate of germination and germinates slowly, and Desi, which shows improved germination properties. Desi produced more NO than Kabuli and had lower respiratory rates. As a result of the high respiration rates, Kabuli had higher levels of reactive oxygen species (ROS). Treatment with the NO donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP) reduced respiration in Kabuli and decreased ROS levels, resulting in accelerated germination rates. These findings suggest that NO plays a key role in the germination of Kabuli. SNAP increased the levels of transcripts encoding enzymes involved in carbohydrate metabolism and the cell cycle. Moreover, the levels of amino acids and organic acids were increased in Kabuli as a result of SNAP treatment. 1 H-nuclear magnetic resonance analysis revealed that Kabuli has a higher capacity for glucose oxidation than Desi. An observed SNAP-induced increase in 13C incorporation into soluble alanine may result from enhanced oxidation of exogenous [13C]glucose via glycolysis and the pentose phosphate pathway. A homozygous hybrid that originated from a recombinant inbred line population of a cross between Desi and Kabuli germinated faster and had increased NO levels and a reduced accumulation of ROS compared with Kabuli. Taken together, these findings demonstrate the importance of NO in chickpea germination via the control of respiration and ROS accumulation.