L-galactono-1,4-lactone dehydrogenase (GLDH) forms part of three subcomplexes of mitochondrial complex I in Arabidopsis thaliana

L-Galactono-1,4-lactone dehydrogenase (GLDH) catalyzes the terminal step of the Smirnoff-Wheeler pathway for vitamin C (L-ascorbate) biosynthesis in plants. A GLDH in gel activity assay was developed to biochemically investigate GLDH localization in plant mitochondria. It previously has been shown that GLDH forms part of an 850-kDa complex that represents a minor form of the respiratory NADH dehydrogenase complex (complex I). Because accumulation of complex I is disturbed in the absence of GLDH, a role of this enzyme in complex I assembly has been proposed. Here we report that GLDH is associated with two further protein complexes. Using native gel electrophoresis procedures in combination with the in gel GLDH activity assay and immunoblotting, two mitochondrial complexes of 470 and 420 kDa were identified. Both complexes are of very low abundance. Protein identifications by mass spectrometry revealed that they include subunits of complex I. Finally, the 850-kDa complex was further investigated and shown to include the complete "peripheral arm" of complex I. GLDH is attached to a membrane domain, which represents a major fragment of the "membrane arm" of complex I. Taken together, our data further support a role of GLDH during complex I formation, which is based on its binding to specific assembly intermediates

NaHCO3 impairs the growth and fruit yield of tomato plants

Underground water enriched in NaHCO3 is used in farms of the Buenos Aires province for tomato crop irrigation. This farming practice leads to salt accumulation and soil impairment after several seasons of cultivation inside the greenhouses. This work assayed the effect of NaHCO3 on tomato fruit production. Plants of the Elpida variety of Solanum lycopersicum L were grown in a hydroponic system. The presence of NaHCO3 (from 5 mM, as measured in the underground water to 10 or 20 mM) reduced K+/Na+ ratio and whole plant biomass and fruit yield; however, no effect was observed on fruit quality parameters. To test the participation of ascorbic acid in the tolerance to this stress, two slggp1 Micro-Tom mutant lines deficient in this antioxidant were used. In these experiments plants were treated with 0, 5 and 10 mM NaHCO3 causing an impairment of K+/Na+ ratio, photosynthesis, fruit yield, leaf and shoot dry weight (but without effect in root biomass) and delaying of fruit ripening time. Wild type and mutants plant responses showed no differences at stress conditions. Although NaHCO3 treatments caused a similar impairment in ascorbic acid mutants and wild type plants, these results reinforced the physiological importance of ascorbic acid levels to optimize plant growth under non-stressful conditions. Taken as a whole, the results presented here demonstrated the importance of avoiding the accumulation of this salt in greenhouse soils to optimize tomato production

Potential use of polymeric particles for the regulation of plant growth

Plant growth regulators (PGRs) are molecules widely applied in the agriculture, leading to increased crop yield and improved quality of agricultural products. These compounds act as plant hormones, affecting the plant hormonal homeostasis, and thus control plant growth and development. Recently, the development of polymer-based modified release systems for PGRs has emerged as a promising alternative for increasing the efficacy of these compounds. This review will focus on polymeric particles that are used as carrier systems for PGRs, allowing their controlled release and protecting them from degradation. Successful examples include the phytohormone gibberellic acid(GA3)-loaded nanoparticles, which showed higher efficacy than the non-nano active ingredient in promoting seed germination and seedling growth, and salicylic acid (SA) and nitric oxide (NO)-releasing nanoparticles as effective plant protection agents against stresses. Polymeric nanomaterials per se such as chitosan (Cs) can also alter plant signaling pathways and promote plant growth and development. Despite their great potential in improving the plant production with less damage to the environment, relatively few studies have focused on the use of these nanomaterials for the development of modified release systems for PGRs. In this scenario, this review discusses on the major advances and obstacles in the area.Fil: Pereira, Anderson E. S.. Universidade Estadual Paulista Julio de Mesquita Filho. Faculdade de Engenharia; BrasilFil: Sousa, Bruno T.. Universidade Estadual de Londrina; BrasilFil: Iglesias, María José. 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: Alvarez, Vera Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Casalongue, Claudia. 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: Oliveira, Halley C.. Universidade Estadual de Londrina; BrasilFil: Fraceto, Leonardo F.. Universidade Estadual Paulista Julio de Mesquita Filho. Faculdade de Engenharia; Brasi