Effect of the Nonpathogenic Strain Fusarium oxysporum FO12 on Fe Acquisition in Rice (Oryza sativa L.) Plants

Rice (Oryza sativa L.) is a very important cereal worldwide, since it is the staple food for more than half of the world's population. Iron (Fe) deficiency is among the most important agronomical concerns in calcareous soils where rice plants may suffer from this deficiency. Current production systems are based on the use of high-yielding varieties and the application of large quantities of agrochemicals, which can cause major environmental problems. The use of beneficial rhizosphere microorganisms is considered a relevant sustainable alternative to synthetic fertilizers. The main goal of this study was to determine the ability of the nonpathogenic strain Fusarium oxysporum FO12 to induce Fe-deficiency responses in rice plants and its effects on plant growth and Fe chlorosis. Experiments were carried out under hydroponic system conditions. Our results show that the root inoculation of rice plants with FO12 promotes the production of phytosiderophores and plant growth while reducing Fe chlorosis symptoms after several days of cultivation. Moreover, Fe-related genes are upregulated by FO12 at certain times in inoculated plants regardless of Fe conditions. This microorganism also colonizes root cortical tissues. In conclusion, FO12 enhances Fe-deficiency responses in rice plants, achieves growth promotion, and reduces Fe chlorosis symptoms.

NO Is Not the Same as GSNO in the Regulation of Fe Deficiency Responses by Dicot Plants

Iron (Fe) is abundant in soils but with a poor availability for plants, especially in calcareous soils. To favor its acquisition, plants develop morphological and physiological responses, mainly in their roots, known as Fe deficiency responses. In dicot plants, the regulation of these responses is not totally known, but some hormones and signaling molecules, such as auxin, ethylene, glutathione (GSH), nitric oxide (NO) and S-nitrosoglutathione (GSNO), have been involved in their activation. Most of these substances, including auxin, ethylene, GSH and NO, increase their production in Fe-deficient roots while GSNO, derived from GSH and NO, decreases its content. This paradoxical result could be explained with the increased expression and activity in Fe-deficient roots of the GSNO reductase (GSNOR) enzyme, which decomposes GSNO to oxidized glutathione (GSSG) and NH3. The fact that NO content increases while GSNO decreases in Fe-deficient roots suggests that NO and GSNO do not play the same role in the regulation of Fe deficiency responses. This review is an update of the results supporting a role for NO, GSNO and GSNOR in the regulation of Fe deficiency responses. The possible roles of NO and GSNO are discussed by taking into account their mode of action through post-translational modifications, such as S-nitrosylation, and through their interactions with the hormones auxin and ethylene, directly related to the activation of morphological and physiological responses to Fe deficiency in dicot plants.

The nonpathogenic strain of Fusarium oxysporum FO12 induces Fe deficiency responses in cucumber (Cucumis sativus L.) plants

MAIN CONCLUSION

FO12 strain enhances Fe deficiency responses in cucumber plants, probably through the production of ethylene and NO in the subapical regions of the roots. Rhizosphere microorganisms can elicit induced systemic resistance (ISR) in plants. This type of resistance involves complex mechanisms that confer protection to the plant against pathogen attack. Additionally, it has been reported by several studies that ISR and Fe deficiency responses are modulated by common pathways, involving some phytohormones and signaling molecules, like ethylene and nitric oxide (NO). The aim of this study was to determine whether the nonpathogenic strain of Fusarium oxysporum FO12 can induce Fe deficiency responses in cucumber (Cucumis sativus L.) plants. Our results demonstrate that the root inoculation of cucumber plants with the FO12 strain promotes plant growth after several days of cultivation, as well as rhizosphere acidification and enhancement of ferric reductase activity. Moreover, Fe-related genes, such as FRO1, IRT1 and HA1, are upregulated at certain times after FO12 inoculation either upon Fe-deficiency or Fe-sufficient conditions. Furthermore, it has been found that this fungus colonizes root cortical tissues, promoting the upregulation of ethylene synthesis genes and NO production in the root subapical regions. To better understand the effects of the FO12 strain on field conditions, cucumber plants were inoculated and cultivated in a calcareous soil under greenhouse conditions. The results obtained show a modification of some physiological parameters in the inoculated plants, such as flowering and reduction of tissue necrosis. Overall, the results suggest that the FO12 strain could have a great potential as a Fe biofertilizer and biostimulant.

Holistic view of biological nitrogen fixation and phosphorus mobilization in Azotobacter chroococcum NCIMB 8003

Nitrogen (N) and phosphorus (P) deficiencies are two of the most agronomic problems that cause significant decrease in crop yield and quality. N and P chemical fertilizers are widely used in current agriculture, causing environmental problems and increasing production costs. Therefore, the development of alternative strategies to reduce the use of chemical fertilizers while maintaining N and P inputs are being investigated. Although dinitrogen is an abundant gas in the atmosphere, it requires biological nitrogen fixation (BNF) to be transformed into ammonium, a nitrogen source assimilable by living organisms. This process is bioenergetically expensive and, therefore, highly regulated. Factors like availability of other essential elements, as phosphorus, strongly influence BNF. However, the molecular mechanisms of these interactions are unclear. In this work, a physiological characterization of BNF and phosphorus mobilization (PM) from an insoluble form (Ca₃(PO₄)₂) in Azotobacter chroococcum NCIMB 8003 was carried out. These processes were analyzed by quantitative proteomics in order to detect their molecular requirements and interactions. BNF led to a metabolic change beyond the proteins strictly necessary to carry out the process, including the metabolism related to other elements, like phosphorus. Also, changes in cell mobility, heme group synthesis and oxidative stress responses were observed. This study also revealed two phosphatases that seem to have the main role in PM, an exopolyphosphatase and a non-specific alkaline phosphatase PhoX. When both BNF and PM processes take place simultaneously, the synthesis of nitrogenous bases and L-methionine were also affected. Thus, although the interdependence is still unknown, possible biotechnological applications of these processes should take into account the indicated factors.

A shoot derived long distance iron signal may act upstream of the IMA peptides in the regulation of Fe deficiency responses in Arabidopsis thaliana roots

When plants suffer from Fe deficiency, they develop morphological and physiological responses, mainly in their roots, aimed to facilitate Fe mobilization and uptake. Once Fe has been acquired in sufficient quantity, the responses need to be switched off to avoid Fe toxicity and to conserve energy. Several hormones and signaling molecules, such as ethylene, auxin and nitric oxide, have been involved in the activation of Fe deficiency responses in Strategy I plants. These hormones and signaling molecules have almost no effect when applied to plants grown under Fe-sufficient conditions, which suggests the existence of a repressive signal related to the internal Fe content. The nature of this repressive signal is not known yet many experimental results suggest that is not related to the whole root Fe content but to some kind of Fe compound moving from leaves to roots through the phloem. After that, this signal has been named LOng-Distance Iron Signal (LODIS). Very recently, a novel family of small peptides, "IRON MAN" (IMA), has been identified as key components of the induction of Fe deficiency responses. However, the relationship between LODIS and IMA peptides is not known. The main objective of this work has been to clarify the relationship between both signals. For this, we have used Arabidopsis wild type (WT) Columbia and two of its mutants, opt3 and frd3, affected, either directly or indirectly, in the transport of Fe (LODIS) through the phloem. Both mutants present constitutive activation of Fe acquisition genes when grown in a Fe-sufficient medium despite the high accumulation of Fe in their roots. Arabidopsis WT Columbia plants and both mutants were treated with foliar application of Fe, and later on the expression of IMA and Fe acquisition genes was analyzed. The results obtained suggest that LODIS may act upstream of IMA peptides in the regulation of Fe deficiency responses in roots. The possible regulation of IMA peptides by ethylene has also been studied. Results obtained with ethylene precursors and inhibitors, and occurrence of ethylene-responsive cis-acting elements in the promoters of IMA genes, suggest that IMA peptides could also be regulated by ethylene.

To grow or not to grow under nutrient scarcity: Target of rapamycin-ethylene is the question

To cope with nutrient scarcity, plants generally follow two main complementary strategies. On the one hand, they can slow down growing, mainly shoot growth, to diminish the demand of nutrients. We can call this strategy as "stop growing." On the other hand, plants can develop different physiological and morphological responses, mainly in their roots, aimed to facilitate the acquisition of nutrients. We can call this second strategy as "searching for nutrients." Both strategies are compatible and can function simultaneously but the interconnection between them is not yet well-known. In relation to the "stop growing" strategy, it is known that the TOR (Target Of Rapamycin) system is a central regulator of growth in response to nutrients in eukaryotic cells. TOR is a protein complex with kinase activity that promotes protein synthesis and growth while some SnRK (Sucrose non-fermenting 1-Related protein Kinases) and GCN (General Control Non-derepressible) kinases act antagonistically. It is also known that some SnRKs and GCNs are activated by nutrient deficiencies while TOR is active under nutrient sufficiency. In relation to the "searching for nutrients" strategy, it is known that the plant hormone ethylene participates in the activation of many nutrient deficiency responses. In this Mini Review, we discuss the possible role of ethylene as the hub connecting the "stop growing" strategy and the "searching for nutrients" strategy since very recent results also suggest a clear relationship of ethylene with the TOR system.

Several Yeast Species Induce Iron Deficiency Responses in Cucumber Plants (Cucumis sativus L.)

Iron (Fe) deficiency is a first-order agronomic problem that causes a significant decrease in crop yield and quality. Paradoxically, Fe is very abundant in most soils, mainly in its oxidized form, but is poorly soluble and with low availability for plants. In order to alleviate this situation, plants develop different morphological and physiological Fe-deficiency responses, mainly in their roots, to facilitate Fe mobilization and acquisition. Even so, Fe fertilizers, mainly Fe chelates, are widely used in modern agriculture, causing environmental problems and increasing the costs of production, due to the high prices of these products. One of the most sustainable and promising alternatives to the use of agrochemicals is the better management of the rhizosphere and the beneficial microbial communities presented there. The main objective of this research has been to evaluate the ability of several yeast species, such as Debaryomyces hansenii, Saccharomyces cerevisiae and Hansenula polymorpha, to induce Fe-deficiency responses in cucumber plants. To date, there are no studies on the roles played by yeasts on the Fe nutrition of plants. Experiments were carried out with cucumber plants grown in a hydroponic growth system. The effects of the three yeast species on some of the most important Fe-deficiency responses developed by dicot (Strategy I) plants, such as enhanced ferric reductase activity and Fe²⁺ transport, acidification of the rhizosphere, and proliferation of subapical root hairs, were evaluated. The results obtained show the inductive character of the three yeast species, mainly of Debaryomyces hansenii and Hansenula polymorpha, on the Fe-deficiency responses evaluated in this study. This opens a promising line of study on the use of these microorganisms as Fe biofertilizers in a more sustainable and environmentally friendly agriculture.

Driftage: a multi-agent system framework for concept drift detection

BACKGROUND

The amount of data and behavior changes in society happens at a swift pace in this interconnected world. Consequently, machine learning algorithms lose accuracy because they do not know these new patterns. This change in the data pattern is known as concept drift. There exist many approaches for dealing with these drifts. Usually, these methods are costly to implement because they require (i) knowledge of drift detection algorithms, (ii) software engineering strategies, and (iii) continuous maintenance concerning new drifts.

RESULTS

This article proposes to create Driftage: a new framework using multi-agent systems to simplify the implementation of concept drift detectors considerably and divide concept drift detection responsibilities between agents, enhancing explainability of each part of drift detection. As a case study, we illustrate our strategy using a muscle activity monitor of electromyography. We show a reduction in the number of false-positive drifts detected, improving detection interpretability, and enabling concept drift detectors' interactivity with other knowledge bases.

CONCLUSION

We conclude that using Driftage, arises a new paradigm to implement concept drift algorithms with multi-agent architecture that contributes to split drift detection responsability, algorithms interpretability and more dynamic algorithms adaptation.

Ethylene and Nitric Oxide Involvement in the Regulation of Fe and P Deficiency Responses in Dicotyledonous Plants

Iron (Fe) and phosphorus (P) are two essential elements for plant growth. Both elements are abundant in soils but with poor availability for plants, which favor their acquisition by developing morphological and physiological responses in their roots. Although the regulation of the genes related to these responses is not totally known, ethylene (ET) and nitric oxide (NO) have been involved in the activation of both Fe-related and P-related genes. The common involvement of ET and NO suggests that they must act in conjunction with other specific signals, more closely related to each deficiency. Among the specific signals involved in the regulation of Fe- or P-related genes have been proposed Fe-peptides (or Fe ion itself) and microRNAs, like miR399 (P), moving through the phloem. These Fe- or P-related phloem signals could interact with ET/NO and confer specificity to the responses to each deficiency, avoiding the induction of the specific responses when ET/NO increase due to other nutrient deficiencies or stresses. Besides the specificity conferred by these signals, ET itself could confer specificity to the responses to Fe- or P-deficiency by acting through different signaling pathways in each case. Given the above considerations, there are preliminary results suggesting that ET could regulate different nutrient responses by acting both in conjunction with other signals and through different signaling pathways. Because of the close relationship among these two elements, a better knowledge of the physiological and molecular basis of their interaction is necessary to improve their nutrition and to avoid the problems associated with their misuse. As examples of this interaction, it is known that Fe chlorosis can be induced, under certain circumstances, by a P over- fertilization. On the other hand, Fe oxides can have a role in the immobilization of P in soils. Qualitative and quantitative assessment of the dynamic of known Fe- and P-related genes expression, selected ad hoc and involved in each of these deficiencies, would allow us to get a profound knowledge of the processes that regulate the responses to both deficiencies. The better knowledge of the regulation by ET of the responses to these deficiencies is necessary to properly understand the interactions between Fe and P. This will allow the obtention of more efficient varieties in the absorption of P and Fe, and the use of more rational management techniques for P and Fe fertilization. This will contribute to minimize the environmental impacts caused by the use of P and Fe fertilizers (Fe chelates) in agriculture and to adjust the costs for farmers, due to the high prices and/or scarcity of Fe and P fertilizers. This review aims to summarize the latest advances in the knowledge about Fe and P deficiency responses, analyzing the similarities and differences among them and considering the interactions among their main regulators, including some hormones (ethylene) and signaling substances (NO and GSNO) as well as other P- and Fe-related signals.

Influence of Ethylene Signaling in the Crosstalk Between Fe, S, and P Deficiency Responses in Arabidopsis thaliana

To cope with P, S, or Fe deficiency, dicot plants, like Arabidopsis, develop several responses (mainly in their roots) aimed to facilitate the mobilization and uptake of the deficient nutrient. Within these responses are the modification of root morphology, an increased number of transporters, augmented synthesis-release of nutrient solubilizing compounds and the enhancement of some enzymatic activities, like ferric reductase activity (FRA) or phosphatase activity (PA). Once a nutrient has been acquired in enough quantity, these responses should be switched off to minimize energy costs and toxicity. This implies that they are tightly regulated. Although the responses to each deficiency are induced in a rather specific manner, crosstalk between them is frequent and in such a way that P, S, or Fe deficiency can induce responses related to the other two nutrients. The regulation of the responses is not totally known but some hormones and signaling substances have been involved, either as activators [ethylene (ET), auxin, nitric oxide (NO)], or repressors [cytokinins (CKs)]. The plant hormone ET is involved in the regulation of responses to P, S, or Fe deficiency, and this could partly explain the crosstalk between them. In spite of these crosslinks, it can be hypothesized that, to confer the maximum specificity to the responses of each deficiency, ET should act in conjunction with other signals and/or through different transduction pathways. To study this latter possibility, several responses to P, S, or Fe deficiency have been studied in the Arabidopis wild-type cultivar (WT) Columbia and in some of its ethylene signaling mutants (ctr1, ein2-1, ein3eil1) subjected to the three deficiencies. Results show that key elements of the ET transduction pathway, like CTR1, EIN2, and EIN3/EIL1, can play a role in the crosstalk among nutrient deficiency responses.

Ethylene and Phloem Signals Are Involved in the Regulation of Responses to Fe and P Deficiencies in Roots of Strategy I Plants

Iron (Fe) and phosphorus (P) are two essential mineral nutrients whose acquisition by plants presents important environmental and economic implications. Both elements are abundant in most soils but scarcely available to plants. To prevent Fe or P deficiency dicot plants initiate morphological and physiological responses in their roots aimed to specifically acquire these elements. The existence of common signals in Fe and P deficiency pathways suggests the signaling factors must act in conjunction with distinct nutrient-specific signals in order to confer tolerance to each deficiency. Previous works have shown the existence of cross talk between responses to Fe and P deficiency, but details of the associated signaling pathways remain unclear. Herein, the impact of foliar application of either P or Fe on P and Fe responses was studied in P- or Fe-deficient plants of Arabidopsis thaliana, including mutants exhibiting altered Fe or P homeostasis. Ferric reductase and acid phosphatase activities in roots were determined as well as the expression of genes related to P and Fe acquisition. The results obtained showed that Fe deficiency induces the expression of P acquisition genes and phosphatase activity, whereas P deficiency induces the expression of Fe acquisition genes and ferric reductase activity, although only transitorily. Importantly, these responses were reversed upon foliar application of either Fe or P on nutrient-starved plants. Taken together, the results reveal interactions between P- and Fe-related phloem signals originating in the shoots that likely interact with hormones in the roots to initiate adaptive mechanisms to tolerate deficiency of each nutrient.

Induced Systemic Resistance (ISR) and Fe Deficiency Responses in Dicot Plants

Plants develop responses to abiotic stresses, like Fe deficiency. Similarly, plants also develop responses to cope with biotic stresses provoked by biological agents, like pathogens and insects. Some of these responses are limited to the infested damaged organ, but other responses systemically spread far from the infested organ and affect the whole plant. These latter responses include the Systemic Acquired Resistance (SAR) and the Induced Systemic Resistance (ISR). SAR is induced by pathogens and insects while ISR is mediated by beneficial microbes living in the rhizosphere, like bacteria and fungi. These root-associated mutualistic microbes, besides impacting on plant nutrition and growth, can further boost plant defenses, rendering the entire plant more resistant to pathogens and pests. In the last years, it has been found that ISR-eliciting microbes can induce both physiological and morphological responses to Fe deficiency in dicot plants. These results suggest that the regulation of both ISR and Fe deficiency responses overlap, at least partially. Indeed, several hormones and signaling molecules, like ethylene (ET), auxin, and nitric oxide (NO), and the transcription factor MYB72, emerged as key regulators of both processes. This convergence between ISR and Fe deficiency responses opens the way to the use of ISR-eliciting microbes as Fe biofertilizers as well as biopesticides. This review summarizes the progress in the understanding of the molecular overlap in the regulation of ISR and Fe deficiency responses in dicot plants. Root-associated mutualistic microbes, rhizobacteria and rhizofungi species, known for their ability to induce morphological and/or physiological responses to Fe deficiency in dicot plant species are also reviewed herein.

A Shoot Fe Signaling Pathway Requiring the OPT3 Transporter Controls GSNO Reductase and Ethylene in Arabidopsis thaliana Roots

Ethylene, nitric oxide (NO) and glutathione (GSH) increase in Fe-deficient roots of Strategy I species where they participate in the up-regulation of Fe acquisition genes. However, S-nitrosoglutathione (GSNO), derived from NO and GSH, decreases in Fe-deficient roots. GSNO content is regulated by the GSNO-degrading enzyme S-nitrosoglutathione reductase (GSNOR). On the other hand, there are several results showing that the regulation of Fe acquisition genes does not solely depend on hormones and signaling molecules (such as ethylene or NO), which would act as activators, but also on the internal Fe content of plants, which would act as a repressor. Moreover, different results suggest that total Fe in roots is not the repressor of Fe acquisition genes, but rather the repressor is a Fe signal that moves from shoots to roots through the phloem [hereafter named LOng Distance Iron Signal (LODIS)]. To look further in the possible interactions between LODIS, ethylene and GSNOR, we compared Arabidopsis WT Columbia and LODIS-deficient mutant opt3-2 plants subjected to different Fe treatments that alter LODIS content. The opt3-2 mutant is impaired in the loading of shoot Fe into the phloem and presents constitutive expression of Fe acquisition genes. In roots of both Columbia and opt3-2 plants we determined 1-aminocyclopropane-1-carboxylic acid (ACC, ethylene precursor), expression of ethylene synthesis and signaling genes, and GSNOR expression and activity. The results obtained showed that both 'ethylene' (ACC and the expression of ethylene synthesis and signaling genes) and 'GSNOR' (expression and activity) increased in Fe-deficient WT Columbia roots. Additionally, Fe-sufficient opt3-2 roots had higher 'ethylene' and 'GSNOR' than Fe-sufficient WT Columbia roots. The increase of both 'ethylene' and 'GSNOR' was not related to the total root Fe content but to the absence of a Fe shoot signal (LODIS), and was associated with the up-regulation of Fe acquisition genes. The possible relationship between GSNOR(GSNO) and ethylene is discussed.

Ethylene Participates in the Regulation of Fe Deficiency Responses in Strategy I Plants and in Rice

Iron (Fe) is very abundant in most soils but its availability for plants is low, especially in calcareous soils. Plants have been divided into Strategy I and Strategy II species to acquire Fe from soils. Strategy I species apply a reduction-based uptake system which includes all higher plants except the Poaceae. Strategy II species apply a chelation-based uptake system which includes the Poaceae. To cope with Fe deficiency both type of species activate several Fe deficiency responses, mainly in their roots. These responses need to be tightly regulated to avoid Fe toxicity and to conserve energy. Their regulation is not totally understood but some hormones and signaling substances have been implicated. Several years ago it was suggested that ethylene could participate in the regulation of Fe deficiency responses in Strategy I species. In Strategy II species, the role of hormones and signaling substances has been less studied. However, in rice, traditionally considered a Strategy II species but that possesses some characteristics of Strategy I species, it has been recently shown that ethylene can also play a role in the regulation of some of its Fe deficiency responses. Here, we will review and discuss the data supporting a role for ethylene in the regulation of Fe deficiency responses in both Strategy I species and rice. In addition, we will review the data about ethylene and Fe responses related to Strategy II species. We will also discuss the results supporting the action of ethylene through different transduction pathways and its interaction with other signals, such as certain Fe-related repressive signals occurring in the phloem sap. Finally, the possible implication of ethylene in the interactions among Fe deficiency responses and the responses to other nutrient deficiencies in the plant will be addressed.

Ethylene and the Regulation of Physiological and Morphological Responses to Nutrient Deficiencies

To cope with nutrient deficiencies, plants develop both morphological and physiological responses. The regulation of these responses is not totally understood, but some hormones and signaling substances have been implicated. It was suggested several years ago that ethylene participates in the regulation of responses to iron and phosphorous deficiency. More recently, its role has been extended to other deficiencies, such as potassium, sulfur, and others. The role of ethylene in so many deficiencies suggests that, to confer specificity to the different responses, it should act through different transduction pathways and/or in conjunction with other signals. In this update, the data supporting a role for ethylene in the regulation of responses to different nutrient deficiencies will be reviewed. In addition, the results suggesting the action of ethylene through different transduction pathways and its interaction with other hormones and signaling substances will be discussed.

Soil temperature determines the reaction of olive cultivars to Verticillium dahliae pathotypes

BACKGROUND

Development of Verticillium wilt in olive, caused by the soil-borne fungus Verticillium dahliae, can be influenced by biotic and environmental factors. In this study we modeled i) the combined effects of biotic factors (i.e., pathotype virulence and cultivar susceptibility) and abiotic factors (i.e., soil temperature) on disease development and ii) the relationship between disease severity and several remote sensing parameters and plant stress indicators.

METHODOLOGY

Plants of Arbequina and Picual olive cultivars inoculated with isolates of defoliating and non-defoliating V. dahliae pathotypes were grown in soil tanks with a range of soil temperatures from 16 to 32°C. Disease progression was correlated with plant stress parameters (i.e., leaf temperature, steady-state chlorophyll fluorescence, photochemical reflectance index, chlorophyll content, and ethylene production) and plant growth-related parameters (i.e., canopy length and dry weight).

FINDINGS

Disease development in plants infected with the defoliating pathotype was faster and more severe in Picual. Models estimated that infection with the defoliating pathotype was promoted by soil temperatures in a range of 16 to 24°C in cv. Picual and of 20 to 24°C in cv. Arbequina. In the non-defoliating pathotype, soil temperatures ranging from 16 to 20°C were estimated to be most favorable for infection. The relationship between stress-related parameters and disease severity determined by multinomial logistic regression and classification trees was able to detect the effects of V. dahliae infection and colonization on water flow that eventually cause water stress.

CONCLUSIONS

Chlorophyll content, steady-state chlorophyll fluorescence, and leaf temperature were the best indicators for Verticillium wilt detection at early stages of disease development, while ethylene production and photochemical reflectance index were indicators for disease detection at advanced stages. These results provide a better understanding of the differential geographic distribution of V. dahliae pathotypes and to assess the potential effect of climate change on Verticillium wilt development.

Hypoxia and bicarbonate could limit the expression of iron acquisition genes in Strategy I plants by affecting ethylene synthesis and signaling in different ways

In a previous work, it was shown that bicarbonate (one of the most important factors causing Fe chlorosis in Strategy I plants) can limit the expression of several genes involved in Fe acquisition. Hypoxia is considered another important factor causing Fe chlorosis, mainly on calcareous soils. However, to date it is not known whether hypoxia aggravates Fe chlorosis by affecting bicarbonate concentration or by specific negative effects on Fe acquisition. Results found in this work show that hypoxia, generated by eliminating the aeration of the nutrient solution, can limit the expression of several Fe acquisition genes in Fe-deficient Arabidopsis, cucumber and pea plants, like the genes for ferric reductases AtFRO2, PsFRO1 and CsFRO1; iron transporters AtIRT1, PsRIT1 and CsIRT1; H(+) -ATPase CsHA1; and transcription factors AtFIT, AtbHLH38, and AtbHLH39. Interestingly, the limitation of the expression of Fe-acquisition genes by hypoxia did not occur in the Arabidopsis ethylene constitutive mutant ctr1, which suggests that the negative effect of hypoxia is related to ethylene, an hormone involved in the upregulation of Fe acquisition genes. As for hypoxia, results obtained by applying bicarbonate to the nutrient solution suggests that ethylene is also involved in its negative effect, since ACC (1-aminocyclopropane-1-carboxylic acid; ethylene precursor) partially reversed the negative effect of bicarbonate on the expression of Fe acquisition genes. Taken together, the results obtained show that hypoxia and bicarbonate could induce Fe chlorosis by limiting the expression of Fe acquisition genes, probably because each factor negatively affects different steps of ethylene synthesis and/or signaling.

Word frequency and content analysis approach to identify demand patterns in a virtual community of carriers of hepatitis C

Background

Orkut, a Brazilian virtual social network, is responsible for popularization of the Internet among people of low income and educational level. It’s observed that rapid growth of virtual communities can be reached by low cost Internet access in community local area network houses. Orkut poses an important social resource for Brazilian patients with chronic conditions like hepatitis C virus (HCV) carriers, who face several obstacles in adapting to everyday difficulties.

Objective

Identify Patterns of Recurring Demands (PRD) expressed in messages posted by members of virtual communities dedicated to HCV carriers.

Methods

Pre-selection: we identified terms commonly associated to HCV on generic Internet searches (primary Keywords - Kps); Kps were used to identify the most representative HCV communities in a virtual community site (Orkut); all messages published along 8 years on all topics of the community were collected and tabulated; the word frequency was used to construct a “word cloud” (graphic representation of the word frequency) on which was applied a content analysis technique.

Results

The most cited terms expressed: search for information about medications (prescribed and “forbidden”); emphasis on counting time, which were interpreted as surviving expectations; frequent mention of God, doctors, and “husbands” (female carriers were 68%). These elements provided material for further research – they will be useful in the construction of categories in discourse analysis.

Conclusions

The present work is a disclosure of preliminary findings considered original and promising. The word frequency/content analysis approach expressed needs of social support and material assistance that may provide subsidies for further qualitative approach and public health policies aimed to HCV carriers. The study of PRD by word frequency may be useful in identifying demands underestimated by other means.

Ethylene and nitric oxide involvement in the up-regulation of key genes related to iron acquisition and homeostasis in Arabidopsis

In a previous work it was shown that ethylene participates in the up-regulation of several Fe acquisition genes of Arabidopsis, such as AtFIT, AtFRO2, and AtIRT1. In this work the relationship between ethylene and Fe-related genes in Arabidopsis has been looked at in more depth. Genes induced by Fe deficiency regulated by ethylene were searched for. For this, studies were conducted, using microarray analysis and reverse transcription-PCR (RT-PCR), to determine which of the genes up-regulated by Fe deficiency are simultaneously suppressed by two different ethylene inhibitors (cobalt and silver thiosulphate), assessing their regulation by ethylene in additional experiments. In a complementary experiment, it was determined that the Fe-related genes up-regulated by ethylene were also responsive to nitric oxide (NO). Further studies were performed to analyse whether Fe deficiency up-regulates the expression of genes involved in ethylene biosynthesis [S-adenosylmethionine synthetase, 1-aminocyclopropane-1-carboxylate (ACC) synthase, and ACC oxidase genes] and signalling (AtETR1, AtCTR1, AtEIN2, AtEIN3, AtEIL1, and AtEIL3). The results obtained show that both ethylene and NO are involved in the up-regulation of many important Fe-regulated genes of Arabidopsis, such as AtFIT, AtbHLH38, AtbHLH39, AtFRO2, AtIRT1, AtNAS1, AtNAS2, AtFRD3, AtMYB72, and others. In addition, the results show that Fe deficiency up-regulates genes involved in both ethylene synthesis (AtSAM1, AtSAM2, AtACS4, AtACS6, AtACS9, AtACO1, and AtACO2) and signalling (AtETR1, AtCTR1, AtEIN2, AtEIN3, AtEIL1, and AtEIL3) in the roots.

First Report of Southern Blight of Pepper Caused by Sclerotium rolfsii in Southern Spain

In May 2009, a stem rot of pepper (Capsicum annuum L.) occurred in a 20-ha field in Hacienda de Tarazona, Seville, in southern Spain. Affected plants appeared singly or were grouped in circular patches as much as 8 to 10 m in diameter. Early symptoms consisted of water-soaked lesions on crown and lower stem tissue in contact with the soil. Plant foliage became pale green and wilted, followed by a complete collapse of the plant. A dense white mycelial mat formed on the lower stem and crown with 1- to 2-mm-diameter, spherical, tan-to-dark brown sclerotia. Lower stem pieces of 12 plants with early disease symptoms were surface sterilized in 0.5% NaOCl, dried, transferred to acidified potato dextrose agar, and incubated at 25 ± 1°C in the dark. Fast-growing fungal colonies with white mycelium and abundant sclerotia developed after 6 to 10 days of incubation. On the basis of morphological characters, the fungus was identified as Sclerotium rolfsii Sacc. (2). To confirm the identity of the pathogen, the ribosomal DNA internal transcribed spacer was amplified and sequenced for two isolates (one of the two exact sequences was deposited as GenBank Accession No. GU080230). The sequence was 99% similar to sequences of Athelia rolfsii (S. rolfsii) in GenBank. Pathogenicity of two isolates was determined by placing two oat seeds colonized by each isolate 0.5 to 1 cm from the stem of 2-week-old pepper plants cv. Cristal (one plant per pot, eight replicates). Plants were incubated in a growth chamber maintained at 28 ± 1°C with a 14-h photoperiod of 360 μE·m^-2·s^-1 and 60 to 90% relative humidity for 10 days. By the sixth day, discoloration and blight of the foliage and stem was observed. Sclerotia formed around the crown and 88% of the plants died 7 days after inoculation. S. rolfsii was recovered from all affected pepper plants. Noninoculated control plants did not develop symptoms. In southern Spain, S. rolfsii is widely distributed in areas of sugar beet production (1). Because of the wide host range of the pathogen, southern blight could become an important disease of vegetable production in southern Spain. References: (1) R. Jordán-Ramírez et al. IOBC/WPRS Bull. 42:101. 2009. (2) J. E. M. Mordue. CMI Descriptions of Pathogenic Fungi and Bacteria. No. 410, 1974.

17 EFFECT OF A PROGESTERONE INTRAVAGINAL DEVICE ON PREGNANCY RATE IN CROSSBREED DAIRY COWS UNDER TROPICAL CONDITIONS

The objectives of these experiments were to evaluate the effect of intravaginal progesterone device on crossbreed Holstein × Carora on pregnancy rate under 2 conditions: cycling and noncycling cows. The first experiment was conducted on 135 noncycling cows (45 ± 3 days postpartum) divided in 2 groups. The first group was treated with a timed AI procedure using a progesterone device for 9 days with an eCG injection on Day 6 and estradiol benzoate after progesterone device removal followed by AI 48 h later. The second group was not treated and they were checked until they came in heat and were inseminated. The second experiment was performed on 123 cycling cows and they were divided in 2 groups. The first group was submitted to a time AI treatment similar to that in experiment 1, and the second group was not treated and they were inseminated upon heat detection. Pregnancy rate on Day 120 postpartum was recorded and pregnancy rate was compared among the different proportion of Holstein (H) × Carora (C) crossbreed cows. For the first experiment, differences (P < 0.05) were observed between ¾ Carora ¼ Holstein (46.15%) compared with the other crossbreed groups (10% 7/8 H 1/8 C, 21.42% 5/8 H 3/8 C, 29.16% ½ H ½ C). In the second experiment, differences (P < 0.05) were observed between ¾ Carora ¼ Holstein (57.14%) compared with the other crossbreed groups (6.66% 7/8 H 1/8 C, 30.76% 5/8 H 3/8 C, 33.33% ½ H ½ C). For the variable pregnancy rate at 120 days postpartum, significant differences (P < 0.05) were observed in cycling cows (39.2%) treated with the progesterone device v. nontreated cows (21%). In noncycling cows, there were no differences between treated and nontreated cows. In conclusion, the use of progesterone device did not improve pregnancy rate in the noncycling cows, which could be related to the negative energy balance that cows undergo during the first part of gestation. However, the use of the progesterone device in cycling cows did improve the pregnancy rate compared with nontreated, cycling cows. We demonstrated that this dairy farm has a serious problem in detecting estrous, which was help by use of the progesterone device and timed AI. Also, the Carora blood included in dairy animals help them to perform better under tropical conditions and they can became pregnant much faster than animals with a high level of Holstein blood.

Bicarbonate blocks the expression of several genes involved in the physiological responses to Fe deficiency of Strategy I plants

Bicarbonate is considered one of the most important factors causing Fe chlorosis in Strategy I plants, mainly on calcareous soils. Most of its negative effects have been attributed to its capacity to buffer a high pH in soils, which can diminish both Fe solubility and root ferric reductase activity. Besides its pH-mediated effects, previous work has shown that bicarbonate can inhibit the induction of enhanced ferric reductase activity in Fe-deficient Strategy I plants. However, to date it is not known whether bicarbonate affects the upregulation of the ferric reductase gene and other genes involved in Fe acquisition. The objective of this work has been to study the effect of bicarbonate on the expression of several Fe acquisition genes in Arabidopsis (Arabidopsis thaliana L.), pea (Pisum sativum L.), tomato (Lycopersicon esculentum Mill.) and cucumber (Cucumis sativus L.) plants. Genes for ferric reductases AtFRO2, PsFRO1, LeFRO1 and CsFRO1; iron transporters AtITR1, PsRIT1, LeIRT1 and CsIRT1; H⁺-ATPases CsHA1 and CsHA2; and transcription factors AtFIT and LeFER have been examined. The results showed that bicarbonate could induce Fe chlorosis by inhibiting the expression of the ferric reductase, the iron transporter and the H⁺-ATPase genes, probably through alteration of the expression of Fe efficiency reactions (FER) (or FER-like) transcription factors.

Ethylene involvement in the regulation of the H(+)-ATPase CsHA1 gene and of the new isolated ferric reductase CsFRO1 and iron transporter CsIRT1 genes in cucumber plants

In previous works using ethylene inhibitors and precursors, it has been shown that ethylene participates in the regulation of several Fe deficiency stress responses by Strategy I plants, such as enhanced ferric reductase activity, rhizosphere acidification and subapical root hair development. Furthermore, recent evidence suggests that ethylene could regulate the expression of both the ferric reductase and the iron transporter genes of Strategy I plants by affecting the FER (or FER-like) transcription factor. Recently, two H(+)-ATPase genes have been isolated from cucumber roots, CsHA1 and CsHA2. CsHA1 is up-regulated under Fe deficiency while CsHA2 is constitutively expressed. In this work we have cloned and characterized the sequences of the ferric reductase (CsFRO1) and the iron transporter (CsIRT1) genes from cucumber (Cucumis sativus L. cv Ashley). Expression of CsHA1, CsFRO1 and CsIRT1 is diminished in Fe-deficient roots by treatment with ethylene inhibitors, like Co (cobalt) or AOA (aminooxyacetic acid). Treatment with ethylene precursors, like ACC (1-aminocyclopropane-1-carboxylic acid) or Ethephon (2-chloroethylphosphonic acid), resulted in increased CsHA1, CsFRO1 and CsIRT1 transcript levels and increased ferric reductase activity during early stages of Fe deficiency. These results suggest that ethylene is involved in the regulation of CsHA1, CsFRO1 and CsIRT1 gene expression.

Ethylene could influence ferric reductase, iron transporter, and H+-ATPase gene expression by affecting FER (or FER-like) gene activity

In previous works, it has been shown, by using ethylene inhibitors and precursors, that ethylene could participate in the regulation of the enhanced ferric reductase activity of Fe-deficient Strategy I plants. However, it was not known whether ethylene regulates the ferric reductase gene expression or other aspects related to this activity. This paper is a study of the effects of ethylene inhibitors and precursors on the expression of the genes encoding the ferric reductases and iron transporters of Arabidopsis thaliana (FRO2 and IRT1) and Lycopersicon esculentum (=Solanum lycopersicum) (FRO1 and IRT1) plants. The effects of ethylene inhibitors and precursors on the activity of the iron reductase and the iron transporter have been examined in parallel. Also studied were the effects of ethylene inhibitors and precursors on the expression of the H(+)-ATPase genes of cucumber (CsHA1 and CsHA2) and the transcription factor genes of tomato (LeFER) and Arabidopsis (AtFRU or AtFIT1, an LeFER homologue) that regulate ferric reductase, iron transporter, and H(+)-ATPse activity. The results obtained suggest that ethylene participates in the regulation of ferric reductase, the iron transporter, and H(+)-ATPase gene expression by affecting the FER (or FER-like) levels.

Design patterns as aspects: A quantitative assessment

Design patterns offer flexible solutions to common problems in software development. Recent studies have shown that several design patterns involve crosscutting concerns. Unfortunately, object-oriented (OO) abstractions are often not able to modularize those crosscutting concerns, which in turn decrease the system reusability and maintainability. Hence, it is important verifying whether aspect-oriented approaches support improved modularization of crosscutting concerns relative to design patterns. Ideally, quantitative studies should be performed to compare object-oriented and aspect-oriented implementations of classical patterns with respect to important software engineering attributes, such as coupling and cohesion. This paper presents a quantitative study that compares aspect-based and OO solutions for a representative set of design patterns. We have used stringent software engineering attributes as the assessment criteria. We have found that most aspect-oriented solutions improve separation of pattern-related concerns, although some aspect-oriented implementations of specific patterns resulted in higher coupling and more lines of code.

Evidence of a major gene influencing hair length and heat tolerance in Bos taurus cattle

Evidence was found that supports the existence of a major gene (designated as the slick hair gene), dominant in mode of inheritance, that is responsible for producing a very short, sleek hair coat. Cattle with slick hair were observed to maintain lower rectal temperatures (RT). The gene is found in Senepol cattle and criollo (Spanish origin) breeds in Central and South America. This gene is also found in a Venezuelan composite breed, the Carora, formed from the Brown Swiss and a Venezuelan criollo breed. Two sets of backcross matings of normal-haired sire breeds to Senepol crossbred dams assumed to be heterozygous for the slick hair gene resulted in ratios of slick to normal-haired progeny that did not significantly differ from 1:1. Data from Carora x Holstein crossbred cows in Venezuela also support the concept of a major gene that is responsible for the slick hair coat of the Carora breed. Cows that were 75% Holstein: 25% Carora in breed composition segregated with a ratio that did not differ from 1:1, as would be expected from a backcross matinginvolving a dominant gene. The effect of the slick hair gene on RT depended on the degree of heat stress and appeared to be affected by age and/or lactation status. The decreased RT observed for slick-haired crossbred calves compared to normal-haired contemporaries ranged from 0.18 to 0.4 degrees C. An even larger decrease in RT (0.61 degrees C; P < 0.01) was observed in lactating Carora x Holstein F1 crossbred cows, even though it did not appear that these cows were under severe heat stress. The improved thermotolerance of crossbred calves due to their slick hair coats did not result in increased weaning weights, possibly because both the slick and normal-haired calves were being nursed by slick-haired dams. There were indications that the slick-haired calves grew faster immediately following weaning and that their growth during the cooler months of the year was not compromised significantly by their reduced quantity of hair. In the Carora x Holstein crossbred cows there was a positive effect of slick hair on milk yield under dry, tropical conditions.