Senescence-associated vacuoles, a specific lytic compartment for degradation of chloroplast proteins?

Degradation of chloroplasts and chloroplast components is a distinctive feature of leaf senescence. In spite of its importance in the nutrient economy of plants, knowledge about the mechanism(s) involved in the breakdown of chloroplast proteins is incomplete. A novel class of vacuoles, "senescence-associated vacuoles" (SAVs), characterized by intense proteolytic activity appear during senescence in chloroplast-containing cells of leaves. Since SAVs contain some chloroplast proteins, they are candidate organelles to participate in chloroplast breakdown. In this review we discuss the characteristics of SAVs, and their possible involvement in the degradation of Rubisco, the most abundant chloroplast protein. Finally, SAVs are compared with other extra-plastidial protein degradation pathways operating in senescing leaves.Facultad de Ciencias Naturales y MuseoFacultad de Ciencias Agrarias y ForestalesInstituto de Fisiología Vegeta

Contributions of photosynthetic organs to the seed yield of hybrid rice: The effects of gibberellin application examined by carbon isotope technology

The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Contributions of photosynthetic organs to the seed yield of hybrid rice: The effects of gibberellin application examined by carbon isotope technology. Seed Science and Technology, 46(3), (2018): 533-546, doi:10.15258/sst.2018.46.3.10.Changes in the structure and quality of a hybrid combination population have been observed after the application of gibberellins. Such changes would affect the accumulation and distribution of photosynthetic products, which would subsequently affect the yield during hybrid rice seed production. In this study, photosynthetic physiological characteristics and the distribution of photosynthetic products were evaluated in a field experiment. The transport of panicle photosynthetic products to grain was demonstrated using a 14C isotope tracer technique.The contribution ratios of the panicle and leaf to yield in the hybrid rice seed production were 32.3 and 42.1%, respectively. Through isotope tracing technology, it was determined that about 90% of the photosynthetic products of the panicle and 50% of those of the leaf were delivered to the panicle. During the filling period, the contribution of panicle to yield was concentrated in the early period (0–10 days after pollination), and the contribution of leaf to yield was more significant in the late period (10 days after pollination to maturity). These results suggest that the panicle makes an important photosynthetic contribution (equivalent to that of the flag leaf) during the process of grain filling, especially at 0–5 days after the heading stage.We are thankful to anonymous reviewers and editors for their helpful comments and suggestions. This research was part of the project for the National Natural Science Foundation of China (No. 31271666), “12th 5-year plan” Agro-Scientific Research in the Public Interest (Grant No. 201303002) and the Earmarked Fund for China Agriculture Research System (Grant No. CARS-01-26)

Senescence-associated vacuoles, a specific lytic compartment for degradation of chloroplast proteins?

Degradation of chloroplasts and chloroplast components is a distinctive feature of leaf senescence. In spite of its importance in the nutrient economy of plants, knowledge about the mechanism(s) involved in the breakdown of chloroplast proteins is incomplete. A novel class of vacuoles, "senescence-associated vacuoles" (SAVs), characterized by intense proteolytic activity appear during senescence in chloroplast-containing cells of leaves. Since SAVs contain some chloroplast proteins, they are candidate organelles to participate in chloroplast breakdown. In this review we discuss the characteristics of SAVs, and their possible involvement in the degradation of Rubisco, the most abundant chloroplast protein. Finally, SAVs are compared with other extra-plastidial protein degradation pathways operating in senescing leaves.Facultad de Ciencias Naturales y MuseoFacultad de Ciencias Agrarias y ForestalesInstituto de Fisiología Vegeta

'Senescence-associated vacuoles' are involved in the degradation of chloroplast proteins in tobacco leaves

Massive degradation of photosynthetic proteins is the hallmark of leaf senescence; however the mechanism involved in chloroplast protein breakdown is not completely understood. As small 'senescence-associated vacuoles' (SAVs) with intense proteolytic activity accumulate in senescing leaves of soybean and Arabidopsis, the main goal of this work was to determine whether SAVs are involved in the degradation of chloroplastic components. SAVs with protease activity were readily detected through confocal microscopy of naturally senescing leaves of tobacco (Nicotiana tabacum L.). In detached leaves incubated in darkness, acceleration of the chloroplast degradation rate by ethylene treatment correlated with a twofold increase in the number of SAVs per cell, compared to untreated leaves. In a tobacco line expressing GFP targeted to plastids, GFP was re-located to SAVs in senescing leaves. SAVs were isolated by sucrose density gradient centrifugation. Isolated SAVs contained chloroplast-targeted GFP and the chloroplast stromal proteins Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) and glutamine synthetase, but lacked the thylakoid proteins D1 and light-harvesting complex II of the photosystem II reaction center and photosystem II antenna, respectively. In SAVs incubated at 30°C, there was a steady decrease in Rubisco levels, which was completely abolished by addition of protease inhibitors. These results indicate that SAVs are involved in degradation of the soluble photosynthetic proteins of the chloroplast stroma during senescence of leaves.Instituto de Fisiología Vegeta

Photosynthesis in non‐foliar tissues: implications for yield

Photosynthesis is currently a focus for crop improvement, however the majority of this work has taken place and been assessed in leaves, whilst limited consideration has been given to the contribution that other green tissues make to whole plant carbon assimilation. The major focus of this review is to evaluate the impact of non‐foliar photosynthesis on carbon use efficiency and total assimilation. Here we appraise and summarise past and current literature on the substantial contribution of different photosynthetically active organs and tissues to productivity in a variety of different plant types, with an emphasis on fruit and cereal crops. Previous studies provide evidence that non‐leaf photosynthesis could be an unexploited potential target for crop improvement. We also briefly examine the role of stomata in non‐foliar tissues and their role in gas exchange, maintenance of optimal temperatures and thus photosynthesis. In the final section, we discuss possible opportunities to manipulate these processes and provide evidence that wheat plants genetically manipulated to increase leaf photosynthesis, also displayed higher rates of ear assimilation, which translated to increased grain yield. By understanding these processes, we can start to provide insights into manipulating non‐foliar photosynthesis and stomatal behaviour to identify novel targets for exploitation for on‐going breeding programmes

'Senescence-associated vacuoles' are involved in the degradation of chloroplast proteins in tobacco leaves

Massive degradation of photosynthetic proteins is the hallmark of leaf senescence; however the mechanism involved in chloroplast protein breakdown is not completely understood. As small 'senescence-associated vacuoles' (SAVs) with intense proteolytic activity accumulate in senescing leaves of soybean and Arabidopsis, the main goal of this work was to determine whether SAVs are involved in the degradation of chloroplastic components. SAVs with protease activity were readily detected through confocal microscopy of naturally senescing leaves of tobacco (Nicotiana tabacum L.). In detached leaves incubated in darkness, acceleration of the chloroplast degradation rate by ethylene treatment correlated with a twofold increase in the number of SAVs per cell, compared to untreated leaves. In a tobacco line expressing GFP targeted to plastids, GFP was re-located to SAVs in senescing leaves. SAVs were isolated by sucrose density gradient centrifugation. Isolated SAVs contained chloroplast-targeted GFP and the chloroplast stromal proteins Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) and glutamine synthetase, but lacked the thylakoid proteins D1 and light-harvesting complex II of the photosystem II reaction center and photosystem II antenna, respectively. In SAVs incubated at 30°C, there was a steady decrease in Rubisco levels, which was completely abolished by addition of protease inhibitors. These results indicate that SAVs are involved in degradation of the soluble photosynthetic proteins of the chloroplast stroma during senescence of leaves.Instituto de Fisiología Vegeta

Control post emergente de rama negra

Los herbicidas inhibidores de la enzima aceto lactato sintetasa (ALS) son los más utilizados en Rama negra (Conyza bonariensis, Conyza sumatrensis), entre ellos diclosulam, clorimuron; sin embargo, las con¬tinuas fallas y la reciente confirmación de biotipos de esta maleza con resistencia múltiple a glifosato, hormonales e inhibidores de la ALS, lle¬vó a la búsqueda de alternativas químicas que controlen a esta maleza en post emergencia. El objetivo del ensayo fue evaluar la velocidad de quemado y rebrote de rama negra a través de diferentes alternativas químicas de pre siembra de soja.Estación Experimental Agropecuaria General VillegasFil: Lobos, Martín. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Lobos, Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Becario; Argentin

Chlorophyll content variability in different sugarbeet crop cultivars

Measurement of chlorophyll content with portable meters is an easy way to quantify crop nutrient status, but meter readings are affected by different factors (Martinez and Guiamet, 2004), among which cultivar plays an important role (Chapman and Barreto, 1997). The aim of this work was to study the effect of crop cultivar on chlorophyll readings and to study the relationship of chlorophyll content with yield, quality and other eco-physiological and biochemical parameter

Low intensity light treatment improves purple kale (Brassica oleracea var. sabellica) postharvest preservation at room temperature

Purple Kale is a vegetable of the Brassicaceae family whose are popularly consumed in recent years due to their high level of healthy components. For consumption, matures leaves are harvested and postharvest senescence is induced. Changes in color leaves due to chlorophyll degradation are the main visible symptoms of postharvest senescence, but there are other changes that affect the nutritional quality of kale. The aim of this study was to investigate if low intensity light pulses could be used to delay postharvest senescence of purple kale stored at room temperature. Daily treatments with 1 h pulses of white or red light were performed. Irradiated samples had approximately 40% higher chlorophyll and protein and more of 20% higher antioxidant capacity and soluble sugar content than control samples regardless of light quality used in treatment (white or red). Both light treatments improve the appearance and quality of kale during storage at room temperature.Fil: Bárcena, Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Fisiología Vegetal. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Fisiología Vegetal; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales; ArgentinaFil: Martinez, Gustavo Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Fisiología Vegetal. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Fisiología Vegetal; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales; ArgentinaFil: Costa, M.lorenza. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Fisiología Vegetal. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Fisiología Vegetal; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales; Argentin