The effect of adenosine monophosphate deaminase overexpression on the accumulation of umami-related metabolites in tomatoes

Taste is perceived as one of a combination of five sensations, sweet, sour, bitter, salty, and umami. The umami taste is best known as a savoury sensation and plays a central role in food flavour, palatability, and eating satisfaction. Umami flavour can be imparted by the presence of glutamate and is greatly enhanced by the addition of ribonucleotides, such as inosine monophosphate (IMP) and guanosine monophosphate (GMP). The production of IMP is regulated by the enzyme adenosine monophosphate (AMP) deaminase which functions to convert AMP into IMP. We have generated transgenic tomato (Solanum lycopersicum) lines over expressing AMP deaminase under the control of a fruit-specific promoter. The transgenic lines showed substantially enhanced levels of AMP deaminase expression in comparison to the wild-type control. Elevated AMP deaminase levels resulted in the reduced accumulation of glutamate and increased levels of the umami nucleotide GMP. AMP concentrations were unchanged. The effects on the levels of glutamate and GMP were unexpected and are discussed in relation to the metabolite flux within this pathway

Sugar-and-acid profile of Penjar tomatoes and its evolution during storage

The alcobaca mutation in the Penjar tomato (Solanum lycopersicum L.) variety alters the ripening process and confers a long shelf life (more than four months). Storage of Penjar tomatoes leads to a distinctive sensory profile valued by local consumers, who prefer aged tomatoes to fresh ones. To study chemical changes occurring during storage, we characterized the complete sugar-and-acid profile of 25 accessions at harvest and at 2 and 4 months after harvest. We found considerable variability in the sugar-and-acid profile within the Penjar variety, especially for fructose and glucose. Some accessions presented exceptionally high values for sugars, making them especially interesting for breeding programs. During postharvest, the concentration of glucose, fructose, and citric acid decreased, whereas the concentration of malic and glutamic acids increased. Data from this study offer novel insights into postharvest changes in tomato quality parameters and help elucidate the reasons for the appreciation of this variety by consumers.Postprint (published version

In vitro plant regeneration of Spartina argentinensis Parodi

Spartina argentinensis Parodi is the dominant species of the temporally-flooded halophyte communities of the Santa Fe Province, Argentina. It occupies around 20 000 km2 and it is mainly used as low-cost impute forage for cattle production. The objective of this work was to develop a simple method for in vitro plant regeneration of S. argentinensis that could be used for fundamental and applied research. Leaf-basal segments from both young and mature plants, roots tips and immature inflorescences were used as explants. Culture media for callus, shoot and root induction consisted of Murashige & Skoog salts (MS) supplemented with different plant growth regulators (2,4-D; BAP or ANA). Most of the explants (with the exception of root tips) showed cell proliferation and callus formation after 30 days of culture. However, only immature inflorescences responded to shoot and root induction when callus were incubated on MS salts plus 2,4-D and BAP (0,1 and 0,01 mg.l-1, respectively), transferred to shoot induction media (MS salts plus BAP, 0.5 mg.l-1) and then to root induction media (MS salts plus NAA 0.5 mg.l-1). Regenerated plants were evaluated for morphological abnormalities and lignin content. Historical analysis of regenerating callus showed that shoots and roots originated via organogenesis. A low proportion of regenerated plants resulted with deficiency in chlorophyll (albino plants) and other morphological abnormalities. Between regenerated plants significant variations in the lignin content were detected. The protocol described in this work could be used for in vitro plant regeneration of S. argentinensis and selecting somaclonal variants for breeding purposes.Spartina argentinensis Parodi es la especie dominante en comunidades halófitas que ocupan alrededor de 20.000 km2 en la Provincia de Santa Fe, Argentina. El objetivo de este trabajo fue desarrollar un método simple para la regeneración de plantas in vitro de S. argentinensis que podría ser utilizado para la investigación básica y aplicada. Se utilizaron como explantes, segmentos basales de hojas de plantas jóvenes y maduras, puntas de raíces e inflorescencias inmaduras. El medio de cultivo utilizado para callos, brotes e inducción de raíces consistió en la base salina de Murashige y Skoog (MS) suplementado con diferentes reguladores del crecimiento vegetal (2,4-D; BAP ó ANA). La mayoría de los explantes (con excepción de las puntas de raíces) mostró una proliferación celular y formación de callos después de 30 días de cultivo. Sólo las inflorescencias inmaduras regeneraron brotes y raíces cuando los callos se incubaron en sales MS con 2,4-D y BAP (0,1 y 0,01 mg.l-1, respectivamente), posteriormente los callos se transfirieron a medio de inducción de brotes (sales MS, 0,5 mg.l-1 BAP) y luego a medios de inducción de raíz (MS y 0,5 mg.l-1NAA). Las plantas regeneradas se evaluaron para detectar anomalías morfológicas y el contenido de lignina de sus hojas. El análisis histológico de los callos mostró que los brotes y las raíces se originaron vía organogénica. Un bajo porcentaje de las plantas regeneradas mostraron deficiencia de clorofila (plantas albinas) y otras anomalías morfológicas. Entre las plantas regeneradas se detectaron variaciones significativas en el contenido de lignina. El protocolo que se describe en este trabajo podría ser utilizado para la regeneración in vitro de plantas de S. argentinensis y la selección de variantes somaclonales para futuros planes de mejoramiento

In vitro plant regeneration of spartina argentinensis parodi

Título en ingles: Regeneración in vitro de Spartina argentinensis Parodi Resumen: Spartina argentinensis Parodi es la especie dominante en  comunidades halófitas que ocupan alrededor de 20.000 km2 en la Provincia de Santa Fe, Argentina. El objetivo de este trabajo fue desarrollar un método simple para la regeneración de plantas in vitro de S. argentinensis que podría ser utilizado para la investigación básica y aplicada. Se utilizaron como explantes, segmentos basales de hojas de plantas jóvenes y maduras, puntas de raíces e  inflorescencias inmaduras. Los medios de cultivo utilizados para callos, brotes e inducción de raíces consistió en la base salina de Murashige y Skoog suplementado con diferentes reguladores del crecimiento vegetal (2,4-D; BAP o ANA). La mayoría de los explantes (con la excepción de puntas de raíces) mostró una proliferación celular y formación de callos después de 30 días de cultivo. Solo las inflorescencias inmaduras regeneraron brotes y raíces  cuando los callos se incubaron en sales MS con 2,4 -D y BAP (0,1 y 0,01 mg.L-1, respectivamente), posteriormente los callos se transfirieron a medio de inducción de brotes (sales MS,  0,5 mg. L-1 BAP) y luego a medios de inducción de raíz ( MS y 0,5 mg.L-1NAA). Las plantas regeneradas se evaluaron para detectar anomalías morfológicas y el contenido de lignina de sus hojas. El análisis histológico de los callos mostró que los brotes y las raíces se originaron vía  organogénica. Un bajo porcentaje de las plantas regeneradas mostraron deficiencia de clorofila (plantas albinas) y otras anomalías morfológicas. Entre las plantas regeneradas se detectó  variaciones significativas en el contenido de lignina. El protocolo que se describe en este trabajo podría ser utilizado para la regeneración in vitro de plantas de S. argentinensis  y la selección de variantes somaclonales para futuros planes de mejoramiento. Palabras clave: Spartina argentinensis; in vitro; organogénesis; variación somaclonal. Abstract: Spartina argentinensis Parodi is the dominant species of the temporally-flooded halophyte communities of the Santa Fe Province, Argentina. It occupies around 20,000 km2 and it is mainly used as low-cost impute forage for cattle production. The objective of this work was to develop a simple method for in vitro plant regeneration of S. argentinensis that could be used for fundamental and applied research. Leaf-basal segments from both young and mature plants, roots tips and immature inflorescences were used as explants. Culture media for calli, shoot, and root induction consisted of Murashige and amp; Skoog salts supplemented with different plant growth regulators (2,4-D; BAP or ANA). Most of the explants (with the exception of root tips) showed cell proliferation and calli formation after 30 days of culture. However, only immature inflorescences responded to shoot and root induction when calli were incubated on MS salts plus 2,4_D and BAP (0.1 and 0.01 mg.L-1, respectively), transferred to shoot inductionmedia (MS salts plus BAP, 0.5 mg.L-1) and then to root induction media (MS slts plus NAA 0.5 mg.L-1). Regenerated plants were evaluated for morphological abnormalities and lignin content. Historical analysis of regenerating calli showed that shoots and roots originated via organogenesis. A low proportion of regenerated plants resulted with deficiency in chlorophyll (albino plants) and other morphological abnormalities. Interestingly, significant variations in the lignin content were detected between regenerated plants. The protocol described in this work could be used ordinarily for S. argentinensis in vitro plant regeneration and selecting somaclonal variants for breeding purposes. Key words: Spartina argentinensis; in vitro; organogenesis; somaclonal variation