The complexity of nitric oxide generation and function in plants

Plants are exposed to environmental stress, in natural and agricultural conditions.Nitric oxide (NO), a small gaseous molecule which plays important roles in plants, has been involved in many physiological processes, and emerged as an important endogenous signaling molecule in the adaptation of plants to biotic and abiotic stress. NO is produced from a variety of enzymatic and non enzymatic sources, which are not yet fully understood. Also, NO and reactive nitrogen species (RNS) can produce posttranslational modifications affecting protein function. Nitrate reductase, a key enzyme in the nitrogen metabolism, is a proposed source of NO in plants which could be affected by posttranslational modifications.Thus, different pathways seem to be involved and can also regulate NO synthesis in the plant cell under physiological or stress conditions. However, how the levels of NO are reached in such time and place to fulfill its functions, are still puzzles to elucidate.Instituto de Fisiología Vegeta

The stay-green phenotype of TaNAM-RNAi wheat plants is associated with maintenance of chloroplast structure and high enzymatic antioxidant activity

TaNAM transcription factors play an important role in controlling senescence, which in turn, influences the delivery of nitrogen, iron and other elements to the grain of wheat (Triticum aestivum) plants, thus contributing to grain nutritional value. While lack or diminished expression of TaNAMs determines a stay-green phenotype, the precise effect of these factors on chloroplast structure has not been studied. In this work we focused on the events undergone by chloroplasts in two wheat lines having either control or diminished TaNAM expression due to RNA interference (RNAi). It was found that in RNAi plants maintenance of chlorophyll levels and maximal photochemical efficiency of photosystem II were associated with lack of chloroplast dismantling. Flow cytometer studies and electron microscope analysis showed that RNAi plants conserved organelle ultrastructure and complexity. It was also found that senescence in control plants was accompanied by a low leaf enzymatic antioxidant activity. Lack of chloroplast dismantling in RNAi plants was associated with maintenance of protein and iron concentration in the flag leaf, the opposite being observed in control plants. These data provide a structural basis for the observation that down regulation of TaNAMs confers a functional stay-green phenotype and indicate that the low export of iron and nitrogen from the flag leaf of these plants is concomitant, within the developmental window studied, with lack of chloroplast degradation and high enzymatic antioxidant activity.Instituto de Fisiología Vegeta

Seed dormancy in different plot of Panicum coloratum cv. Verde

Panicum coloratum L. (mijo perenne) se encuentra en plena difusión en la Región Semiárida Pampeana por tolerar altas temperaturas y sequías prolongadas. Es una gramínea perenne de crecimiento primavero-estival, nativa del continente africano adaptada a zonas templado-cálidas a tropicales. Pero presenta problemas de dormición de la semilla lo cual dificulta la emergencia uniforme y ocasiona problemas en el establecimiento. Los objetivos de este trabajo fueron: evaluar la duración de la dormición en semillas de diferentes lotes de P. coloratum cv. Verde y el efecto de la temperatura de almacenamiento sobre la dormición. Se examinaron 3 lotes cosechados en Chacharramendi, Luan Toro y Perú (La Pampa). Se acondicionó la semilla y almacenó a temperatura ambiente para realizar ensayos secuenciales de germinación cada 60 días, únicamente las semillas del lote de Luan Toro fueron almacenadas además a -20°C y 7°C. Los ensayos se condujeron en cámara de germinación a una temperatura alterna de 20-30ºC, con fotoperíodo de 8 hs y no se realizó ningún tratamiento para romper la dormición. En lo que respecta a la duración de la dormición, la semilla cosechada manualmente, perdió su dormición entre los cinco y siete meses de almacenamiento, llegando a germinar más del 90% de las semillas viables. En cambio, la semilla que fue cosechada a máquina ya al mes presentó elevada capacidad de germinación, posiblemente por haber sufrido un escarificado mecánico durante la trilla. Las temperaturas bajas hicieron permanecer dormidas más del 50% de las semillas viables durante todo el período estudiado (siete meses).Fil: Checovich, Mariana Leonela. Universidad Nacional de La Pampa; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Ruiz, María de Los Ángeles. Universidad Nacional de La Pampa; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional La Pampa-San Luis; Argentin

The complexity of nitric oxide generation and function in plants

Plants are exposed to environmental stress, in natural and agricultural conditions.Nitric oxide (NO), a small gaseous molecule which plays important roles in plants, has been involved in many physiological processes, and emerged as an important endogenous signaling molecule in the adaptation of plants to biotic and abiotic stress. NO is produced from a variety of enzymatic and non enzymatic sources, which are not yet fully understood. Also, NO and reactive nitrogen species (RNS) can produce posttranslational modifications affecting protein function. Nitrate reductase, a key enzyme in the nitrogen metabolism, is a proposed source of NO in plants which could be affected by posttranslational modifications.Thus, different pathways seem to be involved and can also regulate NO synthesis in the plant cell under physiological or stress conditions. However, how the levels of NO are reached in such time and place to fulfill its functions, are still puzzles to elucidate.Instituto de Fisiología Vegeta

Determination of low-temperature stress during the vegetative stage as a tool to predict plant yield in rice genotypes with contrasting tolerance levels

In this study, the first aim was to develop a rapid and non-destructive method for analysing rice genotypes' tolerance to low temperatures (LT) during the seedling stage. Using a growth parameter and a physiological parameter, a discriminant formula was developed to differentiate between tolerant and sensitive genotypes based on their LT tolerance score. The study identified several benefits of the discriminant formula, including its low classification error rate, scalability, and ability to be used in controlled and reduced environments. Additionally, a second study was conducted, which found a strong correlation between the LT tolerance score during the seedling stage and plant yield at the ripening stage in plants grown under field LT during the vegetative stage. Panicle weight was the main mediator of the effect of the LT tolerance score on plant yield, but the number of panicles per plant also played a role. Overall, the results suggest that the LT tolerance score can serve as an indirect selection factor for plants for both LT tolerance and plant yield. This is especially relevant for rice-growing regions with temperate climates and LT at the beginning of the cultivation season.Fil: Michelini, María Carolina. Ministerio de Ciencia, Tecnología e Innovación Productiva. Agencia Nacional de Promoción Científica y Tecnológica. Fondo para la Investigación Científica y Tecnológica; ArgentinaFil: Gázquez, Ayelén. Universidad Nacional de San Martin. Instituto Tecnologico de Chascomus. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - la Plata. Instituto Tecnologico de Chascomus.; ArgentinaFil: Checovich, Mariana Leonela. Universidad Nacional de San Martin. Instituto Tecnologico de Chascomus. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - la Plata. Instituto Tecnologico de Chascomus.; ArgentinaFil: Salazar Tamayo, Andy. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Maiale, Santiago Javier. Universidad Nacional de San Martin. Instituto Tecnologico de Chascomus. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - la Plata. Instituto Tecnologico de Chascomus.; ArgentinaFil: Menendez, Ana Bernardina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: Rodriguez, Andres Alberto. Universidad Nacional de San Martin. Instituto Tecnologico de Chascomus. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - la Plata. Instituto Tecnologico de Chascomus.; Argentin