Nitric oxide regulation of leaf phosphoenolpyruvate carboxylase-kinase activity: implication in sorghum responses to salinity

Nitric oxide (NO) is a signaling molecule that mediates many plant responses to biotic and abiotic stresses, including salt stress. Interestingly, salinity increases NO production selectively in mesophyll cells of sorghum leaves, where photosynthetic C4 phosphoenolpyruvate carboxylase (C4 PEPCase) is located. PEPCase is regulated by a phosphoenolpyruvate carboxylase-kinase (PEPCase-k), which levels are greatly enhanced by salinity in sorghum. This work investigated whether NO is involved in this effect. NO donors (SNP, SNAP), the inhibitor of NO synthesis NNA, and the NO scavenger cPTIO were used for long- and short-term treatments. Long-term treatments had multifaceted consequences on both PPCK gene expression and PEPCase-k activity, and they also decreased photosynthetic gas-exchange parameters and plant growth. Nonetheless, it could be observed that SNP increased PEPCase-k activity, resembling salinity effect. Short-term treatments with NO donors, which did not change photosynthetic gas-exchange parameters and PPCK gene expression, increased PEPCase-k activity both in illuminated leaves and in leaves kept at dark. At least in part, these effects were independent on protein synthesis. PEPCase-k activity was not decreased by short-term treatment with cycloheximide in NaCl-treated plants; on the contrary, it was decreased by cPTIO. In summary, NO donors mimicked salt effect on PEPCase-k activity, and scavenging of NO abolished it. Collectively, these results indicate that NO is involved in the complex control of PEPCase-k activity, and it may mediate some of the plant responses to salinity.Fil: Monreal, José A.. Universidad de Sevilla; EspañaFil: Arias Baldrich, Cirenia. Universidad de Sevilla; EspañaFil: Tossi, Vanesa Eleonora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Biológicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Feria, Ana B.. Universidad de Sevilla; EspañaFil: Rubio Casal, Alfredo. Universidad de Sevilla; EspañaFil: García Mata, Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Biológicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Lamattina, Lorenzo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Biológicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: García Mauriño, Sofía. Universidad de Sevilla; Españ

Decoding the interaction between Nitric Oxide and hydrogen sulfide in stomatal movement

Stomatal pore regulation is a key process for carbon and water homeostasis of terrestrial plants. The pore size is modulated through changes in the guard cell volume, driven by variations in the osmotic potential of the guard cells. This process is closely regulated by a complex signaling network that involves the participation of several second messengers including gasotransmitters. The importance of gaseous molecules in signaling has been highlighted in the last decade and, in plants, has been reported to modulate many adaptive responses todifferent biotic and abiotic stresses including the regulation of stomatal movement in response to drought stress. Nitric oxide (NO) and hydrogen sulfide (H2S) have been reported to close the stomata in different plant species, and itsthe production, mode of action, and interplay between them and with other molecules are under constant review. Recently, the interest in animal research has drifted to the functional role of nitroxyl (HNO/NO−), an alternative redox form of NO which is formed by biochemical reactions between H2S and NO in vivo. It has been reported that HNO has effects in different processes, and several works have studied the interaction between H2S and different NO donors demonstrating the formation of new chemical species.One of them is the formation of HNO from the mixture of NaHS, a H S donor, and SNP, a NO donor. In our lab, we have preliminary data showing that HNO blocks H2S dependent stomatal closure in Vicia faba.Interestingly, no stomatal closure induction was evidenced when SNP and NaHS were added together, supporting the interaction between these two gasotransmitters.In the current chapter, we summarize the current knowledge and updates on the role of NO and H2S in guard cell signaling.Fil: Scuffi, Denise. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Lamattina, Lorenzo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Garcia-Mata, Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; Argentin