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Identifying novel variation in root anatomical traits for waterlogging and drought tolerance and their genetic basis in wheat and barley
Get PDFClimate change threatens crop yields and food security through changes in rainfall patterns associated with increased frequency of waterlogging and drought. In plants, the Ubiquitin mediated proteolysis, through the Plant Cysteine Oxidase (PCO) branch of the PRT6 N-degron pathway, has been identified as a key regulator of plant developmental and environmental responses. Much of the molecular understanding in the PRT6 N-degron pathway has been established in the genetic model Arabidopsis thaliana. However, there is also evidence that at least some of the molecular components of this pathway are conserved in cereals. For example, it has been shown that this pathway controls sensing low oxygen levels during waterlogging as well as affecting responses to drought and salinity in barley. The N-end rule pathway controls plant responses to hypoxia by regulating the stability of the group VII ethylene response factor (ERFVII) transcription factors, controlled by the oxidation status of amino terminal (Nt)-cysteine (Cys).
Root cortical senescence (RCS) is known as a type of programmed cell death found in the Triticeae tribe and studies suggest that RCS reduces water and nutrient uptake, respiration, and radial hydraulic conductance of root tissue. However, it has been argued that RCS can improve growth under suboptimal availability of water and nutrients, and that it can enable the development of crop varieties with improved drought tolerance. However, how the Ndegron pathway may affect root cortical senescence traits in barley and wheat is not fully understood. The objectives of this study were firstly to evaluate the genetic variation of RCS traits and above-ground physiological traits of barley mutants for the PRT6 gene regulating the N-degron pathway under optimum and waterlogged conditions in controlled environment experiments. Secondly, to quantify the genetic variation of RCS traits and aboveground physiological traits and yield and yield components of barley mutants for the Prt6 gene, as well as of wheat Paragon x Watkins landrace lines, under well-watered and drought-stressed conditions in glasshouse experiments. Thirdly, to quantify the soil greenhouse-gas emissions and physiological traits, yield and yield components in the barley PRT6 mutant lines and the wild type in two field experiments under rain-fed conditions. The mutant Prt6 barley lines in these experiments are in the spring barley Sebastian background with three Prt6 allele mutations tested: prt6k, prt6i and prt6 ubrboxc.
Three barley lines containing mutants alleles for the PRT6 gene in barley (prt6i, prt6k and prt6 ubrboxc) and the Sebastian WT parent were phenotyped under controlled and waterlogging conditions in four controlled-environment experiments, and under well-irrigated and drought conditions in two glasshouse experiments. In addition, these lines were phenotype under rainfed conditions in two field experiments. Furthermore, three Paragon × Watkins landrace lines and the wild type Paragon were phenotype under well-watered and drought conditions in the two glasshouse experiments. In each experiment, the quantification of root anatomical traits, including total aerenchyma area and percentage aerenchyma tissue area in root cross-sections, was carried out for the genotypes (calculated as the percentage of air spaces using images of root cross-sections). Above-ground traits, including leaf chlorophyll content (SPAD), tiller number, dry matter accumulation and yield and yield components at harvest were also measured. In addition, greenhouse gas emissions, including CO2 and N20, were measured in the field experiments.
Results in CE and glasshouse experiments showed the percentage root aerenchyma area was increased under abiotic stress (waterlogging or drought), and for barley genotypes the increases were greater in the prt6i alleles than in the Sebastian wild type. In the present experiments, leaf chlorophyll content retention was not enhanced in the PRT6 mutants compared to the Sebastian WT nor was shoot number per plant or plant height enhanced under waterlogging. So, positive effects on improved shoot growth under waterlogging for these PRT6 mutants could not be confirmed in the present experiments. The barley prt6i allele in the present glasshouse experiments did not respond significantly differently to the drought stress for above-ground traits, despite an increase in absolute area of root aerenchyma and percentage aerenchyma area in this line compared to the Sebastian wild type under drought. These results suggest that the percentage aerenchyma area alone is not a sufficient indicator of drought tolerance without taking into consideration other root and above-ground physiological traits. In the field experiments, biomass at maturity was higher in prt6k compared to WT by 4%. Differences in greenhouse gas emissions were found in the field trial in 2023. CO2 and N20 was higher in prt6k allele compared to the WT by 34% and 20%, respectively.
Future studies should explore the complex interactions between aerenchyma formation and other physiological processes to understand their comprehensive impact on waterlogging and drought resilience. One possible explanation for the lack of drought tolerance despite increased aerenchyma area % could be related to its impact on water transport in xylem vessels. Aerenchyma plays a role in facilitating gas exchange in roots, but its increase might interfere with the hydraulic conductivity of xylem vessels. This could happen if the formation of aerenchyma reduces the mechanical strength of roots or alters their ability to transport water efficiently from roots to shoots. Future studies should also address the application of RCS traits and PRT6 mutant alleles for plant breeding for waterlogging and drought tolerance. For example, by introgression of the prt6 alleles into modern elite high-yielding potential backgrounds and by developing molecular markers for screening germplasm for haplotype variation in the PRT6 gene
Identifying novel variation in root anatomical traits for waterlogging and drought tolerance and their genetic basis in wheat and barley
Get PDFClimate change threatens crop yields and food security through changes in rainfall patterns associated with increased frequency of waterlogging and drought. In plants, the Ubiquitin mediated proteolysis, through the Plant Cysteine Oxidase (PCO) branch of the PRT6 N-degron pathway, has been identified as a key regulator of plant developmental and environmental responses. Much of the molecular understanding in the PRT6 N-degron pathway has been established in the genetic model Arabidopsis thaliana. However, there is also evidence that at least some of the molecular components of this pathway are conserved in cereals. For example, it has been shown that this pathway controls sensing low oxygen levels during waterlogging as well as affecting responses to drought and salinity in barley. The N-end rule pathway controls plant responses to hypoxia by regulating the stability of the group VII ethylene response factor (ERFVII) transcription factors, controlled by the oxidation status of amino terminal (Nt)-cysteine (Cys).
Root cortical senescence (RCS) is known as a type of programmed cell death found in the Triticeae tribe and studies suggest that RCS reduces water and nutrient uptake, respiration, and radial hydraulic conductance of root tissue. However, it has been argued that RCS can improve growth under suboptimal availability of water and nutrients, and that it can enable the development of crop varieties with improved drought tolerance. However, how the Ndegron pathway may affect root cortical senescence traits in barley and wheat is not fully understood. The objectives of this study were firstly to evaluate the genetic variation of RCS traits and above-ground physiological traits of barley mutants for the PRT6 gene regulating the N-degron pathway under optimum and waterlogged conditions in controlled environment experiments. Secondly, to quantify the genetic variation of RCS traits and aboveground physiological traits and yield and yield components of barley mutants for the Prt6 gene, as well as of wheat Paragon x Watkins landrace lines, under well-watered and drought-stressed conditions in glasshouse experiments. Thirdly, to quantify the soil greenhouse-gas emissions and physiological traits, yield and yield components in the barley PRT6 mutant lines and the wild type in two field experiments under rain-fed conditions. The mutant Prt6 barley lines in these experiments are in the spring barley Sebastian background with three Prt6 allele mutations tested: prt6k, prt6i and prt6 ubrboxc.
Three barley lines containing mutants alleles for the PRT6 gene in barley (prt6i, prt6k and prt6 ubrboxc) and the Sebastian WT parent were phenotyped under controlled and waterlogging conditions in four controlled-environment experiments, and under well-irrigated and drought conditions in two glasshouse experiments. In addition, these lines were phenotype under rainfed conditions in two field experiments. Furthermore, three Paragon × Watkins landrace lines and the wild type Paragon were phenotype under well-watered and drought conditions in the two glasshouse experiments. In each experiment, the quantification of root anatomical traits, including total aerenchyma area and percentage aerenchyma tissue area in root cross-sections, was carried out for the genotypes (calculated as the percentage of air spaces using images of root cross-sections). Above-ground traits, including leaf chlorophyll content (SPAD), tiller number, dry matter accumulation and yield and yield components at harvest were also measured. In addition, greenhouse gas emissions, including CO2 and N20, were measured in the field experiments.
Results in CE and glasshouse experiments showed the percentage root aerenchyma area was increased under abiotic stress (waterlogging or drought), and for barley genotypes the increases were greater in the prt6i alleles than in the Sebastian wild type. In the present experiments, leaf chlorophyll content retention was not enhanced in the PRT6 mutants compared to the Sebastian WT nor was shoot number per plant or plant height enhanced under waterlogging. So, positive effects on improved shoot growth under waterlogging for these PRT6 mutants could not be confirmed in the present experiments. The barley prt6i allele in the present glasshouse experiments did not respond significantly differently to the drought stress for above-ground traits, despite an increase in absolute area of root aerenchyma and percentage aerenchyma area in this line compared to the Sebastian wild type under drought. These results suggest that the percentage aerenchyma area alone is not a sufficient indicator of drought tolerance without taking into consideration other root and above-ground physiological traits. In the field experiments, biomass at maturity was higher in prt6k compared to WT by 4%. Differences in greenhouse gas emissions were found in the field trial in 2023. CO2 and N20 was higher in prt6k allele compared to the WT by 34% and 20%, respectively.
Future studies should explore the complex interactions between aerenchyma formation and other physiological processes to understand their comprehensive impact on waterlogging and drought resilience. One possible explanation for the lack of drought tolerance despite increased aerenchyma area % could be related to its impact on water transport in xylem vessels. Aerenchyma plays a role in facilitating gas exchange in roots, but its increase might interfere with the hydraulic conductivity of xylem vessels. This could happen if the formation of aerenchyma reduces the mechanical strength of roots or alters their ability to transport water efficiently from roots to shoots. Future studies should also address the application of RCS traits and PRT6 mutant alleles for plant breeding for waterlogging and drought tolerance. For example, by introgression of the prt6 alleles into modern elite high-yielding potential backgrounds and by developing molecular markers for screening germplasm for haplotype variation in the PRT6 gene
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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