EFICIÊNCIA DE FUNGICIDAS NO CONTROLE DA FERRUGEM ASIÁTICA (Phakopsora pachyrhizi) NA CULTURA DE SOJA
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Soil salinity is a global issue threatening land productivity,
and estimates predict that 50% of all arable land will become
impacted by salinity by 2050. Consequently, it is important to
have a fundamental understanding of crop response to salinity
to minimize economic loss and improve food security. While an
immense amount of research has been performed assessing corn
(Zea mays L.) and soybean [Glycine max (L.) Merr.] response to
salinity, there are few, if any, comprehensive reviews compiling
previously published literature. Th is review provides a detailed
description of our current knowledge on the impacts of salinity
on corn and soybean growth and development. Both osmotic
stress and specifi c ion toxicities with respect to corn and soybean
are addressed. Additionally, potential areas of future
research are recommended.
Os distúrbios hepáticos são doenças ligadas ao fígado. Tendo em vista a gravidade destes distúrbios e as dificuldades em se estabelecer um tratamento para eles, decidiu-se propor um novo modelo de tratamento, utilizando a silimarina, uma planta que vem sendo utilizada desde os tempos antigos na cura de diversas doenças. Diante disso, o objetivo dessa pesquisa foi discutir o real impacto que a silimarina possui nos distúrbios hepáticos. Para isso, esse estudo teve como base uma revisão bibliográfica descritiva, ao qual foi fundamentada em trabalhos científicos já publicados entre os anos de 2018 a 2022 em língua portuguesa e que tratavam especificamente sobre a temática proposta. A coleta de dados se deu em base de banco de dados, tais como Google Acadêmico, Scielo, PubMed e Lilacs, do qual resultaram 21 trabalhos científicos analisados e divulgados no decorrer desse estudo. Nos resultados encontrados, ficou claro observar que a Silimarina contribui para melhorar o intestino e o sistema digestivo em geral; modulando o equilíbrio da microbiota (pelo estímulo a proliferação de lactobacillus e bifidobactérias, o que teria importante efeito papel imunomodulador). Ainda tem ação anti-hepatotóxica, isso significa, ter ativos de proteção ao fígado e por fim, ajuda no tratamento de doenças hepáticas.
Polyploidy, a numerical alteration of the karyotype, is one of the most important mechanisms in plant speciation and diversification, but could also be detected among populations, the cytotypes. For example, Psidium cattleyanum, a polyploid complex, has chromosome numbers ranging from 2n=3x=33 to 2n=12x=132. Polyploidization causes an increase in DNA content, and both modifications may cause alteration in plant growth, physiology, and epigenetics. Based on this possibility, here we aim to verify the influence of the polyploidization on the production of P. cattleyanum essential oil chemotypes. Differences in the DNA contents, as a proxy to different ploidies, were observed and three distinct chemotypes were identified through the chromatographic profile analysis. The Psidium cattleyanum DNA content and qualitative and quantitative characteristics of the essential oils presented a positive relationship. Plants with higher DNA contents presented higher levels of oil production, which was mostly composed of hydrogenated sesquiterpenes, while plants with lower DNA contents produced lower amount of oil, which was mostly composed of hydrogenated monoterpenes. Based on the importance of essential oils, polyploid plants, which present higher DNA content, are recommended as possible matrices for the propagation of new plants with the potential to produce major compounds of agronomic and pharmacological interest.
Polyploidy within Psidium guajava appears to be uncommon but the genus Psidium is represented by di-, tetra-, hexa- and octoploid species. The species and their respective chromosome numbers are: P. guajava and P. polycarpum , 2 n = 22; P. guineense and P. cujavillus , 2 n = 44; P. friedrichsthalianum (El Salvador), 2 n = 44; P. friedrichsthalianum (Costa Rica), 2 n = 66; P. cattleianum f. lucidum , 2 n = 66. Two plants of P. cattleianum were found to be 2 n = 77, a heptaploid number, but whether these plants represent horticultural variants has not been established.
Close resemblance in vegetative characters of the species and gross appearance of the chromosomes of P. guajava and P. polycarpum on the one hand and those of P. guineense and P. cujavillus on the other casts some doubt as to their identities.
p> Background: The water deficit and the low availability of nutrients are factors that limit the growth and productivity of cultivated plants. Objective: To evaluate the effect of nitrogen and water availability on growth, chlorophyll concentration and photosynthetic efficiency of guava plants ( Psidium guajava L. var. cuban red dwarf). Methodology : A completely randomized experiment with bifactorial arrangement was designed under greenhouse conditions. Factor A was composed by two levels of nitrogen availability (N1: 1.0 g of nitrogen per plant, N0: no nitrogen application) and factor B by two levels of water availability (A400: 400 mL of water every three days and A200: 200 mL of water every three days). Results: Indicators of photosynthetic structure gain (leaves and branches per plant) were more sensitive to water and nitrogen availability from the early stages of plant development, showing the highest values in treatments with higher nitrogen supply, regardless of water availability. Stem growth was higher in the treatments with higher nitrogen and water supply at 80 ddt, similar to that observed in leaf growth and branch emission, regardless of water availability. Implications: The findings found provide new knowledge about the plasticity of cuban red dwarf guava to the conditions of water and nitrogen availability contrasting with the conditions of the experimental site. Conclusions: Guava plants respond to nitrogen and water limitations in the substrate, increasing root growth as a survival strategy in environments with scarce soil resources, while floods with higher water and nitrogen availability increase their assimilation capacity, proportionally to the chlorophyll content.</p
A versatile meteorological index for predicting heat stress in dairy cattle remains elusive. Despite numerous attempts at developing such indices and widespread use of some, there is growing skepticism about the accuracy and adequacy of the existing indices as well as the general statistical approach used to develop them. At the same time, precision farming of high-yielding animals in a drastically changing climate calls for more effective prediction and alleviation of heat stress. The present paper revisits classical work on human biometeorology, particularly the apparent temperature scale, to draw inspiration for advancing research on heat stress in dairy cattle. The importance of a detailed, mechanistic understanding of heat transfer and thermoregulation is demonstrated and reiterated. A model from the literature is used to construct a framework for identifying and characterizing conditions of potential heat stress. New parameters are proposed to translate the heat flux calculations based on heat-balance models into more tangible and more useful meteorological indices, including an apparent temperature for cattle and a thermoregulatory exhaustion index. A validation gap in the literature is identified as the main hindrance to the further development and deployment of heat-balance models. Recommendations are presented for systematically addressing this gap in particular and continuing research within the proposed framework in general.
OPEN ACCESS: https://link.springer.com/article/10.1007/s00484-022-02321-2
Traditional plant breeding encompasses repetitive crossing and selection based on morphological traits, while phenotypic selection has been complemented by molecular methods in recent decades. Genome editing with techniques like the CRISPR-Cas9 system is still a novel approach that is being used to make direct modifications to nucleotide sequences of crops. In addition to these genetic alterations, an improved understanding of epigenetic variations such as DNA methylation on the phenotype of plants has led to increased opportunities to accelerate crop improvement. DNA methylation is the most widely studied epigenetic mark in plants and other eukaryotes. These epigenetic marks are highly conserved and involved in altering the activities and functions of developmental signals by catalyzing changes in the chromatin structure through methylation and demethylation. Cytosine methylation (5mC) is the most prevalent modification found in DNA. However, recent identification of N6-methyladenosine (6mA) in plants starts to reveal their critical role in plant development. Epigenetic modifications are actively involved in creating the phenotype by controlling essential biological mechanisms. Epigenetic modifications could be heritable and metastable causing variation in epigenetic status between or within species. However, both genetic and heritable epigenetic variation has the potential to drive natural variation. Hence, epigenome editing might help overcome some of the shortcomings of genome editing (such as gene knockout), which can have significant off-target effects and only enables the loss of a gene’s function. In this review, we have discussed the mechanism underlying DNA methylation and demethylation in plants. Methyltransferases and demethylases are involved in catalyzing specific types of modification. We also discuss the potential role of DNA modifications in crop improvement for meeting the requirements of sustainable and green agriculture.
Plants being sessile are always exposed to various environmental stresses, and to overcome these stresses, modifications at the
epigenetic level can prove vital for their long-term survival. Epigenomics refers to the large-scale study of epigenetic marks on
the genome, which include covalent modifications of histone tails (acetylation, methylation, phosphorylation, ubiquitination,
and the small RNA machinery). Studies based on epigenetics have evolved over the years especially in understanding the
mechanisms at transcriptional and posttranscriptional levels in plants against various environmental stimuli. Epigenomic
changes in plants through induced methylation of specific genes that lead to changes in their expression can help to overcome
various stress conditions. Recent studies suggested that epigenomics has a significant potential for crop improvement in plants.
By the induction and modulation of various cellular processes like DNA methylation, histone modification, and biogenesis of
noncoding RNAs, the plant genome can be activated which can help in achieving a quicker response against various plant
stresses. Epigenetic modifications in plants allow them to adjust under varied environmental stresses by modulating their
phenotypic plasticity and at the same time ensure the quality and yield of crops. The plasticity of the epigenome helps to adapt
the plants during pre- and postdevelopmental processes. The variation in DNA methylation in different organisms exhibits
variable phenotypic responses. The epigenetic changes also occur sequentially in the genome. Various studies indicated that
environmentally stimulated epimutations produce variable responses especially in differentially methylated regions (DMR) that
play a major role in the management of stress conditions in plants. Besides, it has been observed that environmental stresses
cause specific changes in the epigenome that are closely associated with phenotypic modifications. However, the relationship
between epigenetic modifications and phenotypic plasticity is still debatable. In this review, we will be discussing the role of
various factors that allow epigenetic changes to modulate phenotypic plasticity against various abiotic stress in plants.
The search for more environmental friendly herbicides, aiming at the control of agricultural pests, combinated with less harmfulness to human health and the environment has grown. An alternative used by researchers is the application of products of secondary plant metabolism, which are investigated due to their potential bioactivities. Thus, species belonging to the Myrtaceae family are potential in these studies, since this family is recognized for having high biological activity. A species belonging to this genus is Psidium cattleyanum, which has a medicinal effect and its fruits are used in human food. Thus, the objective of this research was to evaluate and compare the phyto-cyto-genotoxicity of aqueous and ethanolic leaf extracts of the specie P. cattleyanum, from plant bioassays, as well as to identify the main classes of compounds present in the extracts. For this, the extracts were prepared, characterized and biological tests were carried out by evaluating, in seeds and seedlings of lettuce and sorghum, the variables: percentage of germination, germination speed index, root growth and aerial growth; and in meristematic lettuce cells the variables: mitotic phases, mitotic index, nuclear alterations and chromosomal alterations. Flavones, flavonones, flavonols, flavononols, flavonoids, alkaloids, resins, xanthones and anthraquinone glycoside were characterized in the ethanolic extract. Both evaluated extracts, in the highest concentration, inhibited the initial plant development. All treatments caused alterations in the mitotic phases and inhibited mitotic index. In addition, the treatments promoted an increase in nuclear and chromosomal alterations. The mechanism of action presented was aneugenic, clastogenic and determined in epigenetic alterations. The ethanolic extract was more cytotoxic, since it had a more expressive effect at a lower concentration. Despite the cytotoxicity of the extracts under study, they promoted alterations at lower levels than the glyphosate positive control.
Guava (Psidium guajava L.), a major fruit crop of the sub-tropical region, is facing a production decline due to drought stress. Morphophysiological responses to drought stress and underlying transcriptional regulations in guava are, largely, unknown. This study evaluated the drought stress tolerance of two guava cultivars, viz. “Gola” and “Surahi,” at morphological and physiological levels regulated differentially by ESTs (Expressed Sequence Tags). The treatments comprises three moisture regimes, viz. To = 100% (control), T1 = 75%, and T2 = 50% of field capacity. There was an overall decrease in both morphological and physiological attributes of studied guava cultivars in response to drought stress. Nonetheless, the water use efficiency of the “Surahi” cultivar increased (41.86%) speculating its higher drought tolerance based on enhanced peroxidase (402%) and catalase (170.21%) activities under 50% field capacity (T2). Moreover, higher proline and flavonoid contents reinforced drought stress retaliation of the “Surahi” cultivar. The differential expression of a significant number of ESTs in “Surahi” (234) as compared to “Gola” (117) cultivar, somehow, regulated its cellular, biological, and molecular functions to strengthen morphophysiological attributes against drought stress as indicated by the upregulation of ESTs related to peroxidase, sucrose synthase (SUS), alcohol dehydrogenase (ADH), and ubiquitin at morphological, biochemical, and physiological levels. In conclusion, the drought stress acclimation of pear-shaped guava cultivar “Surahi” is due to the increased activities of peroxidase (POD) and catalase (CAT) complimented by the upregulation of related ESTs.