Adriana Grandis - Academia.edu (original) (raw)

Papers by Adriana Grandis

Research Square (Research Square), Mar 31, 2023

Journal of Experimental Botany, 2014

Witches' broom disease (WBD) of cacao differs from other typical hemibiotrophic plant diseases by... more Witches' broom disease (WBD) of cacao differs from other typical hemibiotrophic plant diseases by its unusually long biotrophic phase. Plant carbon sources have been proposed to regulate WBD developmental transitions; however, nothing is known about their availability at the plant-fungus interface, the apoplastic fluid of cacao. Data are provided supporting a role for the dynamics of soluble carbon in the apoplastic fluid in prompting the end of the biotrophic phase of infection. Carbon depletion and the consequent fungal sensing of starvation were identified as key signalling factors at the apoplast. MpNEP2, a fungal effector of host necrosis, was found to be up-regulated in an autophagiclike response to carbon starvation in vitro. In addition, the in vivo artificial manipulation of carbon availability in the apoplastic fluid considerably modulated both its expression and plant necrosis rate. Strikingly, infected cacao tissues accumulated intracellular hexoses, and showed stunted photosynthesis and the up-regulation of senescence markers immediately prior to the transition to the necrotrophic phase. These opposite findings of carbon depletion and accumulation in different host cell compartments are discussed within the frame of WBD development. A model is suggested to explain phase transition as a synergic outcome of fungal-related factors released upon sensing of extracellular carbon starvation, and an early senescence of infected tissues probably triggered by intracellular sugar accumulation.

Revista Brasileira de Botânica, 2010

Physiological responses of Amazonian flooded plants to the global climate change). According to t... more Physiological responses of Amazonian flooded plants to the global climate change). According to the last report of IPCC (Intergovernmental Panel of Climatic Change, 2007) an increase in atmospheric CO 2 concentration to ca. 0.072% is predicted to occur until the middle of this century. As a result, a tandem elevation of temperature of ca. +3 °C and a decrease in precipitation are to be expected. It has also been suggested that this scenario may lead to a gradual substitution of the tropical forest for savanna-like vegetation in Eastern parts of the Amazon. Within this perspective, a worth question is how the tree species that make up the Amazonian floodplains will respond to the global climatic change? Although predictions have been quite pessimistic, flooding of part of the Amazon will continue to occur for several years and it is important to understand its synergistic effects within the scenario of climate change. In this work, features related to plant metabolism and hormonal signaling during flooding is revised, and the possible effects that the climatic changes might have on plants from the Amazon are discussed. The information available in the literature suggests that under flooding, plants tend to mobilize storage compounds to supply carbon demand needed for maintenance metabolism under the effect of stress caused by the lack of oxygen. In contrast, under elevated CO 2 concentration, plants tend to increase photosynthesis and biomass. With an increase of about 3 °C these parameters may increase even more. Alternatively, with flooding, there is a general decrease in growth potential and it is possible that while favorable conditions of elevated CO 2 and temperature prevail, the positive effects may be counterbalanced by the negative effects of flooding. Thus, the physiological responses might be imperceptible or promote further growth up to the middle of the 21 st Century for most species that occur in the floodplains. However, if temperature and CO 2 levels surpass the threshold of optimal conditions for most plants, a decrease in physiological activity is to be expected.

Research Square (Research Square), Mar 31, 2023

Journal of Experimental Botany, 2014

Witches' broom disease (WBD) of cacao differs from other typical hemibiotrophic plant diseases by... more Witches' broom disease (WBD) of cacao differs from other typical hemibiotrophic plant diseases by its unusually long biotrophic phase. Plant carbon sources have been proposed to regulate WBD developmental transitions; however, nothing is known about their availability at the plant-fungus interface, the apoplastic fluid of cacao. Data are provided supporting a role for the dynamics of soluble carbon in the apoplastic fluid in prompting the end of the biotrophic phase of infection. Carbon depletion and the consequent fungal sensing of starvation were identified as key signalling factors at the apoplast. MpNEP2, a fungal effector of host necrosis, was found to be up-regulated in an autophagiclike response to carbon starvation in vitro. In addition, the in vivo artificial manipulation of carbon availability in the apoplastic fluid considerably modulated both its expression and plant necrosis rate. Strikingly, infected cacao tissues accumulated intracellular hexoses, and showed stunted photosynthesis and the up-regulation of senescence markers immediately prior to the transition to the necrotrophic phase. These opposite findings of carbon depletion and accumulation in different host cell compartments are discussed within the frame of WBD development. A model is suggested to explain phase transition as a synergic outcome of fungal-related factors released upon sensing of extracellular carbon starvation, and an early senescence of infected tissues probably triggered by intracellular sugar accumulation.

Revista Brasileira de Botânica, 2010

Physiological responses of Amazonian flooded plants to the global climate change). According to t... more Physiological responses of Amazonian flooded plants to the global climate change). According to the last report of IPCC (Intergovernmental Panel of Climatic Change, 2007) an increase in atmospheric CO 2 concentration to ca. 0.072% is predicted to occur until the middle of this century. As a result, a tandem elevation of temperature of ca. +3 °C and a decrease in precipitation are to be expected. It has also been suggested that this scenario may lead to a gradual substitution of the tropical forest for savanna-like vegetation in Eastern parts of the Amazon. Within this perspective, a worth question is how the tree species that make up the Amazonian floodplains will respond to the global climatic change? Although predictions have been quite pessimistic, flooding of part of the Amazon will continue to occur for several years and it is important to understand its synergistic effects within the scenario of climate change. In this work, features related to plant metabolism and hormonal signaling during flooding is revised, and the possible effects that the climatic changes might have on plants from the Amazon are discussed. The information available in the literature suggests that under flooding, plants tend to mobilize storage compounds to supply carbon demand needed for maintenance metabolism under the effect of stress caused by the lack of oxygen. In contrast, under elevated CO 2 concentration, plants tend to increase photosynthesis and biomass. With an increase of about 3 °C these parameters may increase even more. Alternatively, with flooding, there is a general decrease in growth potential and it is possible that while favorable conditions of elevated CO 2 and temperature prevail, the positive effects may be counterbalanced by the negative effects of flooding. Thus, the physiological responses might be imperceptible or promote further growth up to the middle of the 21 st Century for most species that occur in the floodplains. However, if temperature and CO 2 levels surpass the threshold of optimal conditions for most plants, a decrease in physiological activity is to be expected.