Publicações

@article{Silva2021,

title = {Effects of Deficit Irrigation and Huanglongbing on Sweet Orange Trees},

author = {Jefferson Rangel Silva and Rodrigo Marcelli Boaretto and Jéssica Aparecida Lara Lavorenti and Bruna Castriani Ferreira Santos and Helvecio Della Coletta-Filho and Dirceu Mattos},

doi = {10.3389/FPLS.2021.731314/BIBTEX},

issn = {1664462X},

year  = {2021},

date = {2021-01-01},

journal = {Frontiers in Plant Science},

volume = {12},

pages = {2228},

publisher = {Frontiers Media S.A.},

abstract = {This study addresses the interactive effects of deficit irrigation and huanglongbing (HLB) infection on the physiological, biochemical, and oxidative stress responses of sweet orange trees. We sought to answer: (i) What are the causes for the reduction in water uptake in HLB infected plants? (ii) Is the water status of plants negatively affected by HLB infection? (iii) What are the key physiological traits impaired in HLB-infected plants? and (iv) What conditions can mitigate both disease severity and physiological/biochemical impairments in HLB-infected plants? Two water management treatments were applied for 11 weeks to 1-year-old-trees that were either healthy (HLB–) or infected with HLB (+) and grown in 12-L pots. Half of the trees were fully irrigated (FI) to saturation, whereas half were deficit-irrigated (DI) using 40% of the water required to saturate the substrate. Our results demonstrated that: reduced water uptake capacity in HLB+ plants was associated with reduced root growth, leaf area, stomatal conductance, and transpiration. Leaf water potential was not negatively affected by HLB infection. HLB increased leaf respiration rates (ca. 41%) and starch synthesis, downregulated starch breakdown, blocked electron transport, improved oxidative stress, and reduced leaf photosynthesis (ca. 57%) and photorespiration (ca.57%). Deficit irrigation reduced both leaf respiration (ca. 45%) and accumulation of starch (ca.53%) by increasing maltose (ca. 20%), sucrose, glucose, and fructose contents in the leaves, decreasing bacterial population (ca. 9%) and triggering a series of protective measures against further impairments in the physiology and biochemistry of HLB-infected plants. Such results provide a more complete physiological and biochemical overview of HLB-infected plants and can guide future studies to screen genetic tolerance to HLB and improve management strategies under field orchard conditions.},

keywords = {Greening, leaf respiration, leaf water potential, Oxidative stress, photorespiration, photosynthesis, starch metabolism},

pubstate = {published},

tppubtype = {article}

}

@article{Boaretto2020,

title = {The possible role of extra magnesium and nitrogen supply to alleviate stress caused by high irradiation and temperature in lemon trees},

author = {Rodrigo M. Boaretto and Franz W. R. Hippler and Guilherme A. Ferreira and Ricardo A. Azevedo and Jose A. Quaggio and Dirceu Mattos},

url = {https://link.springer.com/article/10.1007/s11104-020-04597-y},

doi = {10.1007/S11104-020-04597-Y/METRICS},

issn = {15735036},

year  = {2020},

date = {2020-01-01},

journal = {Plant and Soil},

volume = {457},

issue = {1-2},

pages = {57-70},

publisher = {Springer Science and Business Media Deutschland GmbH},

abstract = {Aims: Citrus trees are subjected to variation of environmental conditions throughout the annual cycle, especially during the flowering and fruit set. Heat waves have affected the environmental conditions required for optimum crop growth and have reduced fruit yield and quality worldwide. This study aimed to evaluate an extra supply of magnesium (Mg) and/or nitrogen (N) to increase citrus tolerance to excessive increased irradiation and consequent air temperature. Methods: Young lemon trees were grown in a greenhouse with extra Mg, N and Mg + N supply for five months and then exposed to heat for 12 days. After imposing stress condition, photosynthetic and enzymatic antioxidant system parameters were assessed to evaluate the impact of the extra nutrient supply in alleviating stress induced by combination of elevated irradiance and air temperature. Results: Extra nutrient supply increased plant tolerance to the environmental stress, allowing maintenance of high photosynthetic and transpiration rates and low ratio of apparent electron transport rate per photosynthetic carbon assimilated. Enhanced Mg supply also increased activity of the antioxidant enzyme system and decreased the oxidative stress of plants. Trees treated with extra N exhibited increased chlorophyll concentrations and ability to harvest light energy. Conclusions: Citrus trees under stressed condition, such as elevated air temperature and radiation, associated to heat waves, exhibited less damage in the photosynthetic mechanism and high activity of the antioxidant enzymatic system when supplied with extra nutrient. It was concluded that extra Mg and N supply are important tools to prevent damages and enhance lemon trees biochemical and physiological responses to alleviate the harmful effects of unfavorable environmental condition.},

keywords = {Antioxidants, Citrus, Heat stress, Light intensity, Nutrient protection, Oxidative stress, Photochemical damages, photosynthesis, Plant protection},

pubstate = {published},

tppubtype = {article}

}

@article{Santos2019,

title = {Physiological, biochemical and molecular responses to drought conditions in field-grown grafted and ungrafted citrus plants},

author = {Ivanildes Conceição Santos and Alex Alan Furtado Almeida and Carlos Priminho Pirovani and Marcio Gilberto Cardoso Costa and Alessandro Santos Conceição and Walter Santos Soares Filho and Mauricio Antônio Coelho Filho and Abelmon Silva Gesteira},

doi = {10.1016/J.ENVEXPBOT.2019.03.018},

issn = {0098-8472},

year  = {2019},

date = {2019-01-01},

journal = {Environmental and Experimental Botany},

volume = {162},

pages = {406-420},

publisher = {Elsevier},

abstract = {The physiological, biochemical and molecular alterations developed by plants under soil water restriction, especially rootstock, is important to elucidate the mechanisms associated to drought tolerance. In order to verify the influence of rootstock and grafting on drought tolerance of citrus plants, we examined water status, photosynthesis, oxidative stress and gene expression in grafted and ungrafted citrus plants subjected to different soil water regimes (well-watered, moderate and severe drought and rehydrated) under field conditions. Analysis were performed in roots and leaves of six plant combinations: ungrafted ‘Rangpur Santa Cruz’ lime (RL) and ‘Sunki Maravilha’ mandarin (SM), RL and SM grafted onto themselves (RL/RL and SM/SM) and ‘Valencia’ sweet orange (VO) grafted onto RL or SM (VO/RL and VO/SM). Drought stress reduced chloroplastid pigment contents and limited the photosynthetic rate, mainly in RL/RL plants. In contrast, the lowest leaf osmotic potential, the best osmotic adjustment and the greater phenotypic plasticity were observed in SM, SM/SMand VO/SM plants. Phenotypic plasticity and the main components of multivariate analysis showed that the physiological variables, such as Fv/F0, F0/Fm and Fv/Fm, were more responsive to soil water deficit. An increase in the superoxide dismutase (SOD) activity and transcript abundance of mitochondrial SOD [Mn-Fe], especially in the scion onto RL, and chloroplastidic SOD [Cu -Zn], inthe scion onto SM, was also observed under water deficit. Besides, an induction of transcription of genes coding for catalase (CAT X2) and ascorbate peroxidase (APX) was also observed, respectively, in leaves and roots of plants subjected to water deficit. However, such transcription increment did not affect the activity of these enzymes, especially in RL/RL plants. RL plants were more effective in soil water extraction than SM plants, evidenced mainly by the maintenance of leaf gas exchange and increase in the leaf relative water content after rehydration. The grafted plants showed alterations in their responses to the stress factor, expressed by a reduction of photosynthetic rates, changes in pigment contents, activity of antioxidant enzymes and expression of genes associated to the antioxidant metabolism, mainly in RL/RL plants. Plants with ‘Valencia’ scion, regardless of the rootstock studied, showed similar physiological, biochemical and molecular responses when exposed to soil water deficit. Multivariate analysis showed that Fv/F0, F0/Fm and Fv/Fm were the most important physiological variables for discriminating citrus plants subjected to control and soil water deficit conditions.},

keywords = {Citrus rootstock, Gene expression, Oxidative stress, photosynthesis, water deficit},

pubstate = {published},

tppubtype = {article}

}

@article{Martins2018,

title = {Persistence in phytopathogenic bacteria: Do we know enough?},

author = {Paula M. M. Martins and Marcus V. Merfa and Marco A. Takita and Alessandra A. De Souza},

doi = {10.3389/FMICB.2018.01099/BIBTEX},

issn = {1664302X},

year  = {2018},

date = {2018-01-01},

journal = {Frontiers in Microbiology},

volume = {9},

issue = {MAY},

pages = {1099},

publisher = {Frontiers Media S.A.},

abstract = {Phytopathogenic bacteria affect a wide range of crops worldwide and have a negative impact in agriculture due to their associated economic losses and environmental impacts. Together with other biotic and abiotic stress factors, they pose a threat to global food production. Therefore, understanding bacterial survival strategies is an essential step toward the development of new strategies to control plant diseases. One mechanism used by bacteria to survive under stress conditions is the formation of persister cells. Persisters are a small fraction of phenotypic variants within an isogenic population that exhibits multidrug tolerance without undergoing genetic changes. They are dormant cells that survive treatment with antimicrobials by inactivating the metabolic functions that are disrupted by these compounds. They are thus responsible for the recalcitrance of many human diseases, and in the same way, they are thought to contribute to the survival of bacterial phytopathogens under a range of stresses they face in the environment. It is believed that persister cells of bacterial phytopathogens may lead to the reoccurrence of disease by recovering growth and recolonizing the host plant after the end of stress. However, compared to human pathogens, little is known about persister cells in phytopathogens, especially about their genetic regulation. In this review, we describe the overall knowledge on persister cells and their regulation in bacterial phytopathogens, focusing on their ability to survive stress conditions, to recover from dormancy and to maintain virulence.},

keywords = {Crop diseases, Oxidative stress, Persisters, Phytopathogen, Toxin-antitoxin systems, VBNC},

pubstate = {published},

tppubtype = {article}

}