Maize Coleoptiles Research Articles

Análisis de la expresión del gen TRI5 de Fusarium graminearum en coleóptilos de trigo y maíz.

The necrotrophic fungus F. graminearum is responsible for causing Fusarium head blight in wheat and ear rotin maize. This fungal infection leads to reduced crop yields and contamination of the crops with mycotoxinslike trichothecene deoxynivalenol (DON), which can cause poisoning in animals and humans. The productionof DON is facilitated by a set of genes, with the TRI5 gene encoding trichodiene synthase being a key player.While some factors that can activate the TRI5 gene in wheat are known, it's unclear whether this gene isactivated when the fungus infects wheat or maize coleoptiles. This study reveals that using ammonium sulfateas a nitrogen source induces the expression of the TRI5 gene in minimal media. In wheat coleoptiles, F.graminearum forms infection structures at 5 days post-infection (dpi), where the induction of the TRI5 geneoccurs. On the other hand, there is no TRI5 gene induction in maize coleoptiles. Finally, the TRI5 geneexpression in plants was confirmed using semi-quantitative PCR, validating the induction in wheat coleoptilesat 5 dpi.

Measurements and predictions of seedling emergence forces

Quantifying seedling emergence pressure or forces (soil impedance to seedling) during the process of plant emergence is difficult in a practical setting. In this study, a mechanical seedling testing device was designed and calibrated to measure seedling emergence pressures experienced by conical or spherical mechanical seedling in soil with varying compaction levels. The data were analysed to generate regression models for predicting seedling emergence forces. Results showed a high correlation between the seedling emergence pressure and soil resistance. The resultant regression model produced a coefficient of determination (R2) of 0.99. After incorporating the morphological characteristics of soybean cotyledon and maize coleoptile into the model, the predicted seedling emergence forces increased with the soil compaction level. During the emergence process, average emergence force of the soybean seedlings was 11.8 N for the lowest compaction level and 28.5 N for the highest compaction level, and the corresponding values of the maize seedlings were 0.2 N and 0.6 N. In a non-compacted field plot, maize crop had a 95.4% emergence rate and soybean crop had 97.2%, whereas for a compacted plot, the corresponding emergence rates were decreased to 19.1% and 60.5%. Inferences made from the study provide information on the dynamics of soil-seedling interaction, which have important implications for managing soil compaction in crop production.

MICROFLORA AND PLANT PATHOGENIC FUNGI AFFECTING BACTERIA IN GRAPE PLANTATIONS IN UZBEKISTAN

In the presented study, isolation of bacterial strains, viz., Pantoea agglomerans, Priestia megaterium and phytopathogenic micromycetes that cause damage and eventually death of grape crops, came from a 10 to 15-year-old vine plantation. A Pantoea agglomerans gram-negative bacillus facultative and anaerobic bacterium strain achieved isolation from grape plants, with its morphological characteristics studied. Bacterial strains with antifungal activities against phytopathogenic micromycetes succeeded in their identification. Bacterial isolates collected from the vines underwent screening for their growth properties. It was apparent that Pantoea agglomerans actively grew wheat coleoptiles by 2.6 mm and maize coleoptiles by 2.3 mm compared with the control. Observable evidence also showed that sorghum coleoptile actively grew by 1.7 mm compared with the control treatment by 2.9 mm. The 26 Aspergillus sp., 23 Penicillium sp., 25 Fusarium sp., 30 Alternaria sp., and five Curvularia sp. phytopathogenic micromycetes belonging to the genus were notable. Bacterial strains isolated from the vine showed the highest antifungal activity against micromycetes belonging to the genus Penicillium and reduced the radius of phytopathogenic growth to 47–54 mm. Compared with micromycetes belonging to the genus Fusarium, it was also apparent that the pathogen reduced the growth radius to 27–35 mm. Isolation of phytopathogenic micromycetes from the vine allows early detection and prevention of grape diseases. Based on these studies, the identification of antifungal activity of the bacterial strains isolated from the vine and the presence of phytohormones in the culture fluid indicated that it is an essential and environmentally friendly biological tool in the cultivation of grapes for human consumption.

EmergeNet: A novel deep-learning based ensemble segmentation model for emergence timing detection of coleoptile.

The emergence timing of a plant, i.e., the time at which the plant is first visible from the surface of the soil, is an important phenotypic event and is an indicator of the successful establishment and growth of a plant. The paper introduces a novel deep-learning based model called EmergeNet with a customized loss function that adapts to plant growth for coleoptile (a rigid plant tissue that encloses the first leaves of a seedling) emergence timing detection. It can also track its growth from a time-lapse sequence of images with cluttered backgrounds and extreme variations in illumination. EmergeNet is a novel ensemble segmentation model that integrates three different but promising networks, namely, SEResNet, InceptionV3, and VGG19, in the encoder part of its base model, which is the UNet model. EmergeNet can correctly detect the coleoptile at its first emergence when it is tiny and therefore barely visible on the soil surface. The performance of EmergeNet is evaluated using a benchmark dataset called the University of Nebraska-Lincoln Maize Emergence Dataset (UNL-MED). It contains top-view time-lapse images of maize coleoptiles starting before the occurrence of their emergence and continuing until they are about one inch tall. EmergeNet detects the emergence timing with 100% accuracy compared with human-annotated ground-truth. Furthermore, it significantly outperforms UNet by generating very high-quality segmented masks of the coleoptiles in both natural light and dark environmental conditions.

Análisis de glioxalasa I (GLX-I) en maíces nativos de Oaxaca, México, infectados con Aspergillus flavus in vitro

The glyoxalase system plays an important role in various physiological processes in plants when they are subjected to different types of stress, whether physical, chemical or biological. Aspergillus flavus is an aflatoxin-producing fungus that contaminates dry grains, leading to a gradual deterioration of the grains and a significant reduction in their nutritional value. The objective of the present study was to evaluate the activity of the enzyme glyoxalase I (GLX-I) in maize coleoptiles from Oaxaca in response to infection caused by Aspergillus flavus. Nine maize samples from four different races were analyzed. The samples were inoculated with a suspension of Aspergillus flavus spores of known concentration and total protein extraction and quantification were performed on the coleoptiles, and GLX-I activity was determined by quantifying the amount of S-lactoylglutathione produced per minute. In addition, analysis of gene expression by reverse transcriptase polymerase chain reaction (RT-PCR) was performed. The inoculated maize coleoptiles showed symptoms of infection, color changes and wilting. The concentration of total proteins decreased significantly in the extracts of four samples in the presence of the fungus. In the GLX-I analysis, two samples had the highest enzymatic activity in the infected coleoptile extract with respect to the healthy one, in addition to presenting greater expression of the gene in the RT-PCR assay, this due to the response to Aspergillus flavus infection.

Differential abundance proteins associated with rapid growth of etiolated coleoptiles in maize

AbstractSince Charles Darwin discovered growth movements of the shoot tip (coleoptile) toward light, the grass coleoptiles have long been used as a model system to study plant growth. Rapid growth of the coleoptile is vital for successful seed germination and early seedling establishment. However, the proteome changes underlying the rapid growth of the coleoptiles are not yet clear in the model plant maize (Zea mays). In the present study, we investigated proteome changes in vivo occurring in the rapidly growing coleoptiles of maize with two‐dimensional gel electrophoresis combined with mass spectrometry. A quantitative comparison of the proteomes at 1.5, 3, and 5 days after germination showed significant changes in protein profiles with coleoptile growth. As a result, 31 differential abundance proteins (DAPs) representing 44 protein spots were identified, of which 21 DAPs with increased abundances were implied in growth‐related processes, including translational initiation, transcription regulation, protein and other compound synthesis, H+‐transmembrane transport and cytoskeleton organization. The selected DAPs were confirmed by reverse transcription quantitative PCR and immunoblot analysis. We suggested that the rapid growth of the coleoptile is largely due to its ability to quickly enhance relevant cellular processes, especially the increased synthesis of the growth‐related DAPs. The content of indole‐3‐acetic acid, salicylic acid, and jasmonic acid decreased significantly, and the content of gibberellins first decreased and then increased during the elongation of coleoptile. This study provides new insight into the significance of proteome changes in coleoptile growth.

Fusicoccin (FC)-Induced Rapid Growth, Proton Extrusion and Membrane Potential Changes in Maize (Zea mays L.) Coleoptile Cells: Comparison to Auxin Responses

The fungal toxin fusicoccin (FC) induces rapid cell elongation, proton extrusion and plasma membrane hyperpolarization in maize coleoptile cells. Here, these three parameters were simultaneously measured using non-abraded and non-peeled segments with the incubation medium having access to their lumen. The dose–response curve for the FC-induced growth was sigmoidal shaped with the maximum at 10−6 M over 10 h. The amplitudes of the rapid growth and proton extrusion were significantly higher for FC than those for indole-3-acetic acid (IAA). The differences between the membrane potential changes that were observed in the presence of FC and IAA relate to the permanent membrane hyperpolarization for FC and transient hyperpolarization for IAA. It was also found that the lag times of the rapid growth, proton extrusion and membrane hyperpolarization were shorter for FC compared to IAA. At 30 °C, the biphasic kinetics of the IAA-induced growth rate could be changed into a monophasic (parabolic) one, which is characteristic for FC-induced rapid growth. It has been suggested that the rates of the initial phase of the FC- and IAA-induced growth involve two common mechanisms that consist of the proton pumps and potassium channels whose contribution to the action of both effectors on the rapid growth is different.

Suppression of sugar accumulation in coleoptile and mesocotyl cells by light irradiation to etiolated maize seedlings

Sugar accumulation in maize (Zea mays) coleoptile and mesocotyl cells was suppressed when etiolated seedlings were subjected to white light irradiation. Regulation mechanisms of sugar accumulation by light in cells of both organs were studied. Sucrose exudation from the endosperm was suppressed in light-treated seedlings. In addition, the activities and transcript levels of sucrose-phosphate synthase (SPS) in scutella were decreased following light irradiation. These results suggest that sucrose exudation from the endosperm is decreased by the suppression of SPS activities via downregulation of its gene expression. In coleoptiles and mesocotyls, light irradiation also decreased the activities and transcript levels of cell wall-bound invertase, suggesting that phloem unloading processes were suppressed. Thus, inhibition of both sucrose loading from the endosperm and sucrose unloading in coleoptiles and mesocotyls may be involved in the suppression of sugar accumulation in coleoptiles and mesocotyls irradiated with white light.

Some New Methodological and Conceptual Aspects of the "Acid Growth Theory" for the Auxin Action in Maize (Zea mays L.) Coleoptile Segments: Do Acid- and Auxin-Induced Rapid Growth Differ in Their Mechanisms?

Two arguments against the “acid growth theory” of auxin-induced growth were re-examined. First, the lack of a correlation between the IAA-induced growth and medium acidification, which is mainly due to the cuticle, which is a barrier for proton diffusion. Second, acid- and the IAA-induced growth are additive processes, which means that acid and the IAA act via different mechanisms. Here, growth, medium pH, and membrane potential (in some experiments) were simultaneously measured using non-abraded and non-peeled segments but with the incubation medium having access to their lumen. Using such an approach significantly enhances both the IAA-induced growth and proton extrusion (similar to that of abraded segments). Staining the cuticle on the outer and inner epidermis of the coleoptile segments showed that the cuticle architecture differs on both sides of the segments. The dose-response curves for the IAA-induced growth and proton extrusion were bell-shaped with the maximum at 10−4 M over 10 h. The kinetics of the IAA-induced hyperpolarisation was similar to that of the rapid phase of the IAA-induced growth. It is also proposed that the K+/H+ co-transporters are involved in acid-induced growth and that the combined effect of the K+ channels and K+/ H+ co-transporters is responsible for the IAA-induced growth. These findings support the “acid growth theory” of auxin action.

The neonicotinoid insecticide thiamethoxam enhances expression of stress-response genes in Zea mays in an environmentally specific pattern.

Recent studies indicate that thiamethoxam (TMX), a neonicotinoid insecticide, can affect plant responses to environmental stressors, such as neighboring weeds. The molecular mechanisms behind both stable and environmentally specific responses to TMX likely involve genes related to defense and stress responses. We investigated the effect of a TMX seed treatment on global gene expression in maize coleoptiles both under normal conditions and under low ratio red to far-red (R:FR) light stress induced by the presence of neighboring plants. The neighboring plant treatment upregulated genes involved in biotic and abiotic stress responses and affected specific photosynthesis and cell-growth related genes. Low R:FR light may enhance maize resistance to herbivores and pathogens. TMX appears to compromise resistance. The TMX treatment stably repressed many genes that encode proteins involved in biotic stress responses, as well as cell-growth genes. Notably, TMX effects on many genes' expression were conditional on the environment. In response to low R:FR, plants treated with TMX engage genes in the JA pathway, as well as other stress-related response pathways. Neighboring weeds may condition TMX-treated plants to become more stress tolerant.

Auxin action in developing maize coleoptiles: challenges and open questions

ABSTRACT The year 2020 marks the 150th anniversary of the elucidation of the process of plant organ growth at the cellular level by Julius Sachs (1870). In this Addendum to a Review Article in Molecular Plant, we describe this fundamental discovery and argue that the etiolated grass coleoptile still represents the system of choice for the experimental analysis of auxin (indole-3-acetic acid, IAA)-action. With reference to the phenomenon of ‘tissue tension’, we discuss the acid-growth hypotheses of IAA-induced wall loosening and the process of vacuolar expansion, respectively. IAA-mediated elongation appears to be independent of wall acidification, and may be regulated via the secretion of glycoproteins into the outer epidermal wall, whereby turgor (and tissue) pressure provides the ‘driving force’ for growth. As predicted by the “acid growth-hypothesis”, the fungal phytotoxin Fusicoccin (Fc) induces organ elongation via the rapid secretion of protons. We conclude that “cell elongation” can only be understood at the level of the entire organ that displays biomechanical features not established by single cells. This systems-level approach can be traced back to the work of Sachs (1870).

Low-fluence blue light-induced phosphorylation of Zmphot1 mediates the first positive phototropism.

Phototropin1 (phot1) perceives low- to high-fluence blue light stimuli and mediates both the first and second positive phototropisms. High-fluence blue light is known to induce autophosphorylation of phot1, leading to the second positive phototropism. However, the phosphorylation status of phot1 by low-fluence blue light that induces the first positive phototropism had not been observed. Here, we conducted a phosphoproteomic analysis of maize coleoptiles to investigate the fluence-dependent phosphorylation status of Zmphot1. High-fluence blue light induced phosphorylation of Zmphot1 at several sites. Notably, low-fluence blue light significantly increased the phosphorylation level of Ser291 in Zmphot1. Furthermore, Ser291-phosphorylated and Ser369Ser376-diphosphorylated peptides were found to be more abundant in the low-fluence blue light-irradiated sides than in the shaded sides of coleoptiles. The roles of these phosphorylation events in phototropism were explored by heterologous expression of ZmPHOT1 in the Arabidopsis thaliana phot1phot2 mutant. The first positive phototropism was restored in wild-type ZmPHOT1-expressing plants; however, plants expressing S291A-ZmPHOT1 or S369AS376A-ZmPHOT1 showed significantly reduced complementation rates. All transgenic plants tested in this study exhibited a normal second positive phototropism. These findings provide the first indication that low-fluence blue light induces phosphorylation of Zmphot1 and that this induced phosphorylation is crucial for the first positive phototropism.

Effects of Naphthazarin (DHNQ) Combined with Lawsone (NQ-2-OH) or 1,4-Naphthoquinone (NQ) on the Auxin-Induced Growth of Zea mays L. Coleoptile Segments.

Naphthoquinones, plants secondary metabolites are known for their antibacterial, antifungal, anti-inflammatory, anti-cancer and anti-parasitic properties. The biological activity of naphthoquinones is connected with their ability to generate reactive oxygen species and to modify biological molecules at their nucleophilic sites. In our research, the effect of naphthazarin (DHNQ) combined with 2-hydroxy-1,4-naphthoquinone (NQ-2-OH) or 1,4-naphthoquinone (1,4-NQ) on the elongation growth, pH changes of the incubation medium, oxidative stress and redox activity of maize coleoptile cells were investigated. This paper describes experiments performed with maize (Zea mays L.) coleoptile segments, which is a classical model system to study plant cell elongation growth. The data presented clearly demonstrate that lawsone and 1,4-naphthoquinone combined with naphthazarin, at low concentrations (1 and 10 nM), reduced the endogenous and IAA-induced (Indole-3-Acetic Acid) elongation growth of maize coleoptile segments. Those changes in growth correlated with the proton concentration in the incubation medium, which suggests that the changes in the growth of maize coleoptile segments observed in the presence of naphthoquinones are mediated through the activity of PM H+-ATPase. The presence of naphthoquinones induced oxidative stress in the maize coleoptile tissue by producing hydrogen peroxide and causing changes in the redox activity. Moreover, the incubation of maize segments with both naphthoquinones combined with naphthazarin resulted in lipid peroxidation and membrane damage. The regulation of PM H+-ATPase activity, especially its inhibition, may result from two major types of reaction: first, a direct interaction between an enzyme and naphthoquinone, which leads to the covalent modification of the protein thiols and the generation of thioethers, which have been found to alter the activity of the PM H+-ATPases; second, naphthoquinones induce reactive oxygen species (ROS) production, which inhibits PM H+-ATPases by increasing cytosolic Ca2+. This harmful effect was stronger when naphthazarin and 1,4-naphthoquinone were added together. Taking these results into account, it can be suggested that by combining naphthoquinones in small quantities, an alternative to synthetic pesticides could be developed.

Glycome and Proteome Components of Golgi Membranes Are Common between Two Angiosperms with Distinct Cell-Wall Structures.

The plant endoplasmic reticulum-Golgi apparatus is the site of synthesis, assembly, and trafficking of all noncellulosic polysaccharides, proteoglycans, and proteins destined for the cell wall. As grass species make cell walls distinct from those of dicots and noncommelinid monocots, it has been assumed that the differences in cell-wall composition stem from differences in biosynthetic capacities of their respective Golgi. However, immunosorbence-based screens and carbohydrate linkage analysis of polysaccharides in Golgi membranes, enriched by flotation centrifugation from etiolated coleoptiles of maize (Zea mays) and leaves of Arabidopsis (Arabidopsis thaliana), showed that arabinogalactan-proteins and arabinans represent substantial portions of the Golgi-resident polysaccharides not typically found in high abundance in cell walls of either species. Further, hemicelluloses accumulated in Golgi at levels that contrasted with those found in their respective cell walls, with xyloglucans enriched in maize Golgi, and xylans enriched in Arabidopsis. Consistent with this finding, maize Golgi membranes isolated by flotation centrifugation and enriched further by free-flow electrophoresis, yielded >200 proteins known to function in the biosynthesis and metabolism of cell-wall polysaccharides common to all angiosperms, and not just those specific to cell-wall type. We propose that the distinctive compositions of grass primary cell walls compared with other angiosperms result from differential gating or metabolism of secreted polysaccharides post-Golgi by an as-yet unknown mechanism, and not necessarily by differential expression of genes encoding specific synthase complexes.

The Effect of Naphthazarin on the Growth, Electrogenicity, Oxidative Stress, and Microtubule Array in Z. mays Coleoptile Cells Treated With IAA.

Naphthazarin (5,8-dihydroxy-1,4-naphthoquinone, DHNQ) is a naturally occurring 1,4-naphthoquinone derivative. In this study, we focused on elucidating the toxic effect of this secondary metabolite on the growth of plant cells. The dose–response curves that were obtained for the effects of DHNQ on endogenous and IAA-induced growth in maize coleoptile segments differ in shape; in the first case, it is linear, while in the presence of auxin it is bell-shaped with the maximum at 1 μM. It was found that DHNQ at almost all concentrations studied, when added to the incubation medium inhibited endogenous growth (excluding naphthazarin at 0.001 μM) as well as growth in the presence of IAA. Simultaneous measurements of the growth and external medium pH of coleoptile segments indicated that DHNQ diminished or eliminated proton extrusion at all of the concentrations that were used. Interestingly, the oxidative stress in maize coleoptile cells, which was measured as hydrogen peroxide (H2O2) production, catalase activity, redox activity and malondialdehyde (MDA) content, increased at the lower concentrations of DHNQ (<1 μM), thus suggesting a specific character of its action. It was also found that naphthazarin at concentration higher than 0.1 μM caused the depolarization of the membrane potential (Em). An analysis of the organization and anisotropy of the cortical microtubules showed that naphthazarin at all of the concentrations that were studied changed the IAA-induced transverse microtubule reorientation to an oblique reorientation. Our results indicate that naphthazarin diminished the growth of maize coleoptile cells by a broad spectrum of its toxic effects, thereby suggesting that naphthazarin might be a hypothetical component of new bioherbicides and biopesticides.

Single and combined effects of Cd and Pb on the growth, medium pH, membrane potential and metal contents in maize (Zea mays L.) coleoptile segments

The mechanisms of the toxic effects of Cd and Pb on plant cell growth are still poorly understood. In particular, little is known about their interactive effects, which usually occur in the environment. Moreover, the data that do exist in the literature are controversial. This study describes experiments that were performed with maize (Zea mays) coleoptile segments, which is a classical model system for studies of plant cell elongation growth. Cadmium and lead, which were added at 0.1 mM, reduced the endogenous and IAA-induced elongation growth of maize coleoptile cells. When both metals were added together or in sequence, their effect on IAA-induced growth was more toxic. The medium pH changes, which were measured simultaneously with growth, indicated that while Pb stopped IAA-induced proton extrusion, Cd only partially diminished it. Although Cd was generally more accumulated than Pb in the maize coleoptile segments, when IAA was added together with Pb, it significantly increased the accumulation of the metal. The short-term electrophysiological experiments showed that the addition of Cd caused the depolarisation of the membrane potential (Em), whereas Pb caused membrane hyperpolarisation. In the long-term electrophysiological experiments, it was found that the Cd-induced Em changes are complex. In conclusion, these results suggest that the effects of Cd and Pb as well as their combination on the elongation growth of maize coleoptile cells and the accumulation of the metals result, among others, from different ionic mechanisms by which each metal change the membrane potential of the cells.

A comparison of the effects of 1,4-naphthoquinone and 2-hydroxy-1,4-naphthoquinone (lawsone) on indole-3-acetic acid (IAA)-induced growth of maize coleoptile cells

The effects of 1,4-naphthoquinone (NQ) and 2-hydroxy-1,4-naphthoquinone (NQ-2-OH) on indole-3-acetic acid (IAA)-induced growth, medium pH changes and membrane potential (Em) in maize (Zea mays L.) coleoptile cells were determined. In addition, the redox cycling properties of both naphthoquinones were also compared. The dose-response curves constructed for the effects of NQ and NQ-2-OH on endogenous and IAA-induced growth differ in shape. It was found that NQ was by 10–50% more effective in inhibiting IAA-induced growth in maize coleoptile segments than NQ-2-OH. Simultaneous measurements of growth and external medium pH indicated that NQ and NQ-2-OH reduced or eliminated proton extrusion at all of the concentrations used, excluding NQ at 1 µM. It was found that both naphthoquinones at concentrations higher than 10 µM caused the depolarisation of the membrane potential (Em). Additionally, compared to the controls, NQ- and NQ-2-OH-exposure of coleoptile segments, at concentrations higher than 10 µM, caused an elevation of the hydrogen peroxide (H2O2) production and plasma membrane redox activity. The highest catalase activity was observed at 10 µM NQ and it was ca. 18-fold greater (at 4 h) than in the control medium. Moreover, it was also found that NQ and NQ-2-OH, at all concentrations studied, increased the malondialdehyde content of coleoptile segments at 4 h of the experiment. The data presented here are discussed taking into account the “acid growth hypothesis” of auxin action and the mechanisms by which naphthoquinones interact with biological systems.

Seedling development in maize cv. B73 and blue light-mediated proteomic changes in the tip vs. stem of the coleoptile.

In 2009, the draft genome of the reference inbred line of maize (Zea mays L. spp. mays cv. B73) was published so that, using this specific corn variety, molecular analyses of physiological processes became possible. However, the morphology and developmental patterns of B73 maize, compared with that of the more frequently used hybrid varieties, have not yet been analyzed. Here, we describe organ development in seedlings of B73 maize and in those of six other hybrid cultivars, and document significant morphological as well as quantitative differences between these varieties of Z. mays. In a second set of experiments, we used etiolated seedlings of B73 maize to analyze the effect of blue light (BL) on the patterns of proteins in the tip vs. growing region of this sheath-like organ. By using two-dimensional difference gel electrophoresis (2D DIGE), coupled with tandem mass spectrometry, we detected, in the microsomal fraction of maize coleoptile tips, rapid changes in the abundance of protein spots of maize phototropin 1 and several metabolic enzymes. In the sub-apical (growing) region of the coleoptile, proteomic changes were less pronounced. These results suggest that the tip of the coleoptile of B73 maize may serve as a unique model system for dissecting BL responses in a light-sensitive plant organ of known function.

Yes, We Have an Inflation of Reviews: But of the Wrong Kind!

I read with interest Ingo Schubert's short article on the inflationary number and value of review papers (Front. Plant Sci. 7:88. doi: 10.3389/fpls.2016.00088). I wholeheartedly agree with Schubert that far too many reviews are getting published. Many are what I call “catalog” reviews, and any good Ph.D student worth his salt can, with the help of PubMed, make a compilation of the recent (last 5 years) literature on a particular topic within days. Reviews of this kind seldom draw attention to areas of conflict, rarely provide insight into technical difficulties, and often fail to point to challenges for future research. Publishing reviews is an established strategy through which journals can increase their IFs and thereby enlarging the circle of readership. The irony is that the reviews published by the increasing number of third rate journals are of the catalog type and therefore don't get cited. In agreement with Ingo Schubert I would therefore appeal to younger scientists not to succumb to the temptation of writing this kind of review for that class of journal. They are of questionable value and hardly boost one's reputation. Believe that critical reviews are the only type of review article that should be asked for and be delivered. What are the prequisites for the preparation of a critical review? The authors need to be accredited leaders in the field (unfortunately, this is by no means always the case), they should make the effort to read and evaluate the original papers they cite rather than simply cite what was previously cited by others. Above all, they need to accomodate the reader's desire to be directed to controversies, but also to take a standpoint on them. These may seem banal criteria, but they remain frequently unfulfilled. The essence of a good review is not so much as to highlight individual papers but to critically evaluate all the relevant papers on a particular subject. Would like to draw attention to an alternative to a high profile review to focus interest on controversial topical issues. Essentially this is an open debate with the conflicting parties putting their case in writing for the scientific public to judge for themselves whose arguments are the more convincing. I have tried this out twice, in both cases with an extremely positive feedback from reviewers/editors. My first attempt, over 20 years ago, was to put the spotlight on the auxin binding protein (ABP; Hertel, 1995; Venis, 1995). At that time I had become involved in ABP research by being asked by Mike Venis to apply a silver-immmunogold enhanced epipolarzation technique to visualize ABP at the surface of maize coleoptile protoplasts (Diekmann et al., 1995). From the referees reports to this paper I realized just how volatile the situation with ABP was. Since I also knew one of the major opponents to ABP research (Rainer Hertel) quite well, I thought it would be a rewarding experience for the plant community to have the two major opponents in the ABP field engage in an intellectual duel. Not being an ABP-researcher myself it is difficult for me in retrospect to judge how effective this exercise in scientific pugilism was in generating more interest, but it is interesting to note that, after many years of relative stagnation, interest in ABP research has recently flared up (Grones and Friml, 2015). More recently, I managed to persuade three experienced colleagues to voice their opinions on vesicles vs. tubes as a means of transport between the endoplasmic reticulum and the Golgi apparatus (Robinson et al., 2015). This controversy had been going on for years with a number of one-sided reviews in the literature. Again I thought it was time for a public debate on this issue. Based on the comments that I have received, this is undoubtedly the best way to focus attention on a hot topic. But, in the sense that it reveals how established researchers approach and try to solve problems, such articles are of immeasurable didactical value to young scientists. To get such ventures going requires that senior scientists in a particular area take the initiative and volunteer to act as coordinators. This not only involves persuading competitors to “put on the gloves,” but, as I did for the vesicles vs. tubules “fight” to be prepared to set the stage by writing an introduction which draws attention to the conflict under consideration. Ideally, and to promulgate further discussion, journals should also open a discussion forum in a following issue for comments. I encourage others to follow my example and explore further this kind of scientific debate as a worthwhile alternative to conventional reviews.

ER Microsome Preparation and Subsequent IAA Quantification in Maize Coleoptile and Primary Root Tissue.

Auxin is a major growth hormone in plants and the first plant hormone to be discovered and studied (Darwin and Darwin, 1880). The auxin molecule in plants was first identified as indole-3-acetic acid (IAA) by Kögl et al. (1934). Active research over nearly a decade has shed light on many of the molecular mechanisms of its action but the complexity and redundancy of the auxin biosynthetic network raises questions about control of this system. We have shown that some enzymes involved in the YUCCA-route of auxin biosynthesis are not cytosolic but localised to the endoplasmic reticulum (ER) in both Arabidopsis thaliana (YUCCA4.2) (Kriechbaumer et al., 2012) as well as Zea mays (ZmTAR1 and ZmSPI) (Kriechbaumer et al., 2015). This is raising the intriguing possibility of subcellular compartmentation of auxin biosynthesis. To show that maize auxin biosynthesis indeed can take place in microsomal as well as cytosolic cellular fractions from maize seedlings we applied the protocol described here: Microsomes are being isolated from maize coleoptile and primary root tissue, enzyme assays with microsomal and cytosolic fractions using either tryptophan (Trp) or indole- -3pyruvic acid (IPyA) as a substrate are carried out and the auxin IAA is extracted and quantified.