Plant Hairs Research Articles

Discriminative gene co-expression network analysis uncovers novel modules involved in the formation of phosphate deficiency-induced root hairs in Arabidopsis.

Cell fate and differentiation in the Arabidopsis root epidermis are genetically defined but remain plastic to environmental signals such as limited availability of inorganic phosphate (Pi). Root hairs of Pi-deficient plants are more frequent and longer than those of plants grown under Pi-replete conditions. To dissect genes involved in Pi deficiency-induced root hair morphogenesis, we constructed a co-expression network of Pi-responsive genes against a customized database that was assembled from experiments in which differentially expressed genes that encode proteins with validated functions in root hair development were over-represented. To further filter out less relevant genes, we combined this procedure with a search for common cis-regulatory elements in the promoters of the selected genes. In addition to well-described players and processes such as auxin signalling and modifications of primary cell walls, we discovered several novel aspects in the biology of root hairs induced by Pi deficiency, including cell cycle control, putative plastid-to-nucleus signalling, pathogen defence, reprogramming of cell wall-related carbohydrate metabolism, and chromatin remodelling. This approach allows the discovery of novel of aspects of a biological process from transcriptional profiles with high sensitivity and accuracy.

Cytosolic free calcium dynamics as related to hyphal and colony growth in the filamentous fungal pathogen Colletotrichum graminicola

Tip growth of pollen tubes and root hairs of plants is oscillatory and orchestrated by tip-focussed variations of cytosolic free calcium ([Ca2+]cyt). Hyphae of filamentous fungi are also tubular tip-growing cells, and components of the Ca2+ signalling machinery, such as Ca2+ channels and Ca2+ sensors, are known to be important for fungal growth. In this study, we addressed the questions if tip-focussed [Ca2+]cyt transients govern hyphal and whole-colony growth in the maize pathogen Colletotrichum graminicola, and whether colony-wide [Ca2+]cyt dynamics rely on external Ca2+ or internal Ca2+ stores. Ratiometric fluorescence microscopy of individual hyphae expressing the Ca2+ reporter Yellow Cameleon 3.6 revealed that Ca2+ spikes in hyphal tips precede the re-initiation of growth after wounding. Tip-focussed [Ca2+]cyt spikes were also observed in undisturbed growing hyphae. They occurred not regularly and at a higher rate in hyphae growing at a medium-glass interface than in those growing on an agar surface. Hyphal tip growth was non-pulsatile, and growth speed was not correlated with the rate of spike occurrence. A possible relationship of [Ca2+]cyt spike generation and growth of whole colonies was assessed by using a codon-optimized version of the luminescent Ca2+ reporter Aequorin. Depletion of extracellular free Ca2+ abolished [Ca2+]cyt spikes nearly completely, but had only a modest effect on colony growth. In a pharmacological survey, some inhibitors targeting Ca2+ influx or release from internal stores repressed growth strongly. However, although some of those inhibitors also affected [Ca2+]cyt spike generation, the effects on both parameters were not correlated. Collectively, the results indicate that tip growth of C. graminicola is non-pulsatile and not mechanistically linked to tip-focused or global [Ca2+]cyt spikes, which are likely a response to micro-environmental parameters, such as the physical properties of the growth surface.

Exploring Wild Tomato Leaf Extracts in Pesticide Formulations

Crude extracts from the leaves of the wild tomato, Lycopersicon hirsutum f. glabratum accession PI 134417 possess a pestresistance mechanism in their glandular trichomes (plant hairs) and the exudates they produce due to the presence of a mixture of methyl ketones (MKs) that has insecticidal and acaricidal properties. Type IV and VI glandular trichomes on the leaves of PI 134417 grown under greenhouse conditions were counted. Major volatile oils from glandular leaf trichomes were extracted, purified, and quantified using gas chromatography (GC) and mass spectrometry (GC/MS). The main objectives of this investigation were to: 1) monitor seasonal glandular trichomes density on PI 134417 for mass production of MKs and 2) prepare a simplified formulation of MKs for potential use of PI 134417 leaf extracts, which could become a valuable source of natural products, in plant protection against spider mites and cowpea aphids. Type IV and type VI trichomes were greatest (P<0.05) in September and October (97 and 238 trichomes mm-2), respectively. Quantification of MKs in emulsified extracts of PI 134417 revealed the dominance of 2-tridecanone (the 13-carbon methyl ketone) compared to other MKs (2-undecanone, 2-dodecanone, and 2-pentadecanone) on the leaf surface. Crude leaf extracts of PI 134417 prepared in water caused 33 and 22% mortality, whereas, water extracts containing 1% Alkamuls (an organic emulsifier) caused 93 and 82% mortality of spider mites and cowpea aphis, respectively, 1 d after exposure.

The effect of flowering calendula and cuphea plants on Orius insidiosus survival and predation of Aphis glycines

ABSTRACTFlowering oilseed crops have the potential to diversify agroecosystems currently dominated by corn and soybeans and improve the provision of ecosystem services such as pest control. Nectar and pollen feeding may increase natural enemy fitness and searching behaviour, increasing their survival and prey consumption rates. The soybean aphid (Aphis glycines Matsumura; Hemiptera: Aphididae) is a particularly widespread and costly agricultural pest. In this study, we evaluate the effects of two flowering oilseed crops, cuphea and calendula, on the survival of the insidious flower bug (Orius insidiosus Say; Hemiptera: Anthocoridae) and its consumption levels of A. glycines placed on soybean plants. We also evaluated the survival of O. insidiosus when placed on glandular and non-glandular cuphea varieties. The amount of A. glycines that remained unconsumed by O. insidiosus did not differ among treatments. Because mortality levels of O. insidiosus were higher on glandular compared to non-glandular cuphea plants, glandular trichomes, or plant hairs, may play a role in impeding movement and prey consumption by O. insidious.

Mechanics of water collection in plants via morphology change of conical hairs

In an arid area like the Namib Desert, plants and animals obtain moisture needed for life from mist in the air. There, some plants have hairs or fibrous structures on their leaf surface that reportedly collect fresh water from the air. We examined the morphology and function of leaf hairs of plants during water collection under different circumstances. We studied the water collecting mechanics of several plants having fibrous hairs on their leaves: tomato, balsam pear, Berkheya purpurea, and Lychnis sieboldii. This plant was selected for detailed investigation as a model because this plant originated from dry grassland near Mount Aso in Kyusyu, Japan. We found a unique feature of water collection and release in this plant. The cone-shaped hairs having inner microfibers were reversibly converted to crushed plates that were twisted perpendicularly in dry conditions. Microfibers found in the hairs seem to be responsible for water storage and release. Their unique reciprocal morphological changes, cone-shaped hairs transformed into perpendicularly twisted shapes, depend on the moisture level in the air, and water stored during wet external conditions was released onto the leaf in drier conditions. These morphological changes were recorded as a movie. Simulations explained the formation of the twisted structure. In theoretical analyses, twisted structures were found to give higher mechanical strength. Similar phenomena were found in the other plants described above. These findings pave the way to new bioinspired technology for alleviating global water shortages.

Plant secretions prevent wasp parasitism in nests of wool-carder bees, with implications for the diversification of nesting materials in Megachilidae

Bees make use of plant substrates in more ways than any other group of insects, which is probably linked to their diversification and ecological success. The highly diverse Megachilidae use a wide range of plant-derived brood cell-building materials, including plant leaves, mortar made from plant tissue, resin, plant hairs (‘plant wool’), and plant trichome secretions. While certain plant-derived materials are believed to protect nests against microbial decay, this has not been tested, and the factors driving diversification of nesting materials are poorly understood. Here, we investigated the protective effects of plant-derived extrafloral trichome secretions which female European wool-carder bees, Anthidium manicatum, smear on their brood cells. By breeding bees in cages with differential resource supply we generated brood cells with or without trichome secretions. Brood cells with trichome secretions were less attractive to parasitic wasps (Monodontomerus obscurus) in Y-maze olfactometer tests. Also, when exposed at sites where A. manicatum occurs in natural populations, brood cells smeared with trichome secretions were less affected by wasp (Melittobia acasta) parasitism than those without trichome secretions. On the other hand, trichome secretions did not prevent the growth of mold on brood cells, and larval mortality due to microbial decay was almost non-existent even when brood cells were exposed to rainfall. We conclude that the use of plant trichome secretion for brood cell construction has more likely evolved to create enemy-free space in response to chalcidoid wasp parasitism. Parasitoids are likely an underestimated cause of the diversification of cell construction materials and adaptive radiation in megachilid bees.

Stinging hairs on the Japanese nettleUrtica thunbergianahave a defensive function against mammalian but not insect herbivores

AbstractThorns and hairs of plants can serve as defenses against herbivores, although they may not have evolved under selection by herbivory. Japanese nettles,Urtica thunbergiana, in Nara Park, Nara Prefecture, Japan, where sika deer have been protected for 1200 years, bear many more stinging hairs than those in areas with few or no deer. Previous studies suggested that such hairy nettles evolved under natural selection imposed by intense deer browsing, because stinging hairs deterred deer browsing and because among‐population variation in hair density was associated with deer abundance. To confirm this hypothesis, we examined (1) whether stinging hairs affected oviposition and feeding preferences of herbivorous insects and (2) the degree to which they deterred deer via laboratory and field experiments with hairy nettles from Nara Park and with almost‐hairless nettles from another area. A specialist butterfly, Indian red admiral, showed no oviposition or larval feeding preferences for either hairy or hairless nettles. Insect damage levels did not significantly differ between the two variants. In contrast, deer browsed hairless nettles more heavily than hairy ones. In hairy nettles, however, the level of deer browsing was not proportional to stinging‐hair density, presumably because the hairy nettle population had reached a plateau for resistance as a result of long‐term strong directional selection for stinging hairs. These results corroborate the hypothesis that hairy nettles in Nara Park evolved through natural selection under intense deer browsing.

Morphogenesis of root nodules in white clover. III. The effect of mutation in nod IJ genes of the microsymbiont upon the DNA level in the host tissue

On the basis of cytophotometric measurements a slightly increased DNA level in the nuclei of curled root hairs containing infection threads was observed in white clover inoculated with wild and mutant strains of &lt;em&gt;Rhizobium leguminosarum&lt;/em&gt; biovar. &lt;em&gt;trifolii&lt;/em&gt;, as compared to normal root hairs of te same plants. Cells of the root nodule primordia in 72 h after the inoculation, as compared to the root primary cortex, demonstrated an increased level of the nuclear DNA. No differences were observed in the nuclear DNA contents in individual layers of the cortex of the 28 day-old nodules. Generally it was low, varying from 2c to 4c. The meristematic and bacteroidal tissues in the effective nodules were characterized by a higher DNA level, as compared to the respective zones in ineffective nodules induced with the strains ANU261 (&lt;em&gt;nod I&lt;sup&gt;*&lt;/sup&gt;&lt;/em&gt;) and ANU262 (&lt;em&gt;nod J&lt;sup&gt;*&lt;/sup&gt;&lt;/em&gt;). The DNA level in the effective bacteroidal tissue varied from 4c to 32c, while in the tissue containing the strain ANU26l only the 2c-8c nuclei could be found and in the tissue with the strain ANU262 - the 4c-16c nuclei.

Trichome Isolation and Integrity Test from Brassica villosa and Other Species

The outward growths from one or more epidermal cells are well known as trichomes (plant hair cells) (Levin, 1973; Mathur, 2006). Preparation of pure intact non-glandular trichomes from trichome-rich Brassica villosa depended on rendering the trichomes sufficiently stiff to dislodge them from the leaves in an undamaged state, which can be further used for structural, transcriptome, genome and biochemical or chemical analysis. Dislodging the flexible trichomes from Brassica villosa (B. villosa) with a paintbrush [as in Zhang and Oppenheimer (2004)] proved too gentle, and scraping trichomes off the leaves with a razor blade [as in Zhang and Oppenheimer (2004)] resulted in trichome cell disruption. Aziz et al. (2005) reported isolating alfalfa glandular trichomes by shearing in liquid nitrogen (N2). In the present study, a similar method was used. Non-glandular leaf trichomes were isolated by treating tissue with liquid N2 to stiffen the flexible trichomes, followed by 1 min of shearing force with a common vortex mixer to dislodge the trichomes from their leaf bed (Nayidu et al., 2014). Up-to ~20 % of the trichomes were removed from the leaf surface and the majority were unbroken (confirmed by no staining by trypan blue; Figure 1). Trichomes were then purified by straining a tissue/trichome/water mixture through a sieve. However, leaf tissues also became very brittle after dipping in liquid N2 and broke up into very small pieces if the leaf tissue was agitated for a longer time period. Hence, N2-treated leaf samples could not be re-used to recover remaining attached trichomes. Contaminating leaf pieces from a 1 min shear were larger and easily to separate manually from the detached trichomes within the sieve, rendering a purified intact trichome preparation. The method was also successful at purifying trichomes from soybean (Glycine max) and tomato (Solanum lycopersicum).

Linear glandular trichomes of Helianthus (Asteraceae): morphology, localization, metabolite activity and occurrence

Capitate glandular trichomes of sunflower are well investigated, but detailed studies are lacking for the linear glandular trichomes (LGT), a second type of physiologically active plant hair present on the surface of sunflowers. Light, fluorescence and scanning electron microscopy as well as histochemical staining were used to investigate the structure and metabolite deposition of LGT. Consisting of 6–11 linearly arranged cells, LGT were found on the surface of most plant organs of Helianthus annuus. They were associated with the leaf vascular system, and also occurred along petioles, stems and the abaxial surface of chaffy bracts, ray and disc florets. The highest density was found on the abaxial surface of phyllaries. Phenotypically similar LGT were common in all species of the genus, but also occurred in most other genera of the Helianthinae so far screened. Brownish and fluorescent metabolites of an as yet unknown chemical structure, together with terpenoids, were produced and stored in apical cells of LGT. The deposition of compounds gradually progressed from the tip cell to the basal cells of older trichomes. This process was accompanied by nucleus degradation in metabolite-accumulating cells. The localization of these trichomes on prominent plant parts of the apical bud and the capitulum combined with the accumulation of terpenoids and other as yet unknown compounds suggests a chemo-ecological function of the LGT in plant–insect or plant–herbivore interaction.

Karakterisasi fenotip kultivar padi tahan dan rentan wereng coklat, Nilaparvata lugens Stål. (Hemiptera: Delphacidae)

The brown planthopper, Nilaparvata lugens Stal. is a destructive and widespread insect pest throughout the rice areas in Indonesia. Rice plant resistance is an effective method in controlling N. lugens. However, the resistance sources and how their mechanism for imparting induced resistance against brown planthopper remains to be nderstood. This research was aimed to identify plant hair and protein banding patterns, as a genetic expression, of resistant and susceptible varieties. Identification of the variation of number of plant hair were carried out by using binocular microscope, while the protein banding patterns was detected by separation on SDS-Page. Co-variants analysis was adopted to identify the groups of resistant cultivars based on protein banding patterns. The results showed that plant hair on resistant rice cultivars are different with susceptible cultivars (resistance to Pelita I/1). The plant hair on resistant cultivars are larger/longer, more abudant and grew tighter than on susceptible cultivar. However the number of plant hair have no correlation with resistance level. In the absence of brown plant hopper infestation, the expression of protein total of resistant and susceptible cultivars are not clearly separated. Pelita I/1 varieties showed a similar banding pattern to IR 26 (biotype 1), IR 42 (resistance to biotype 2) and IR IR 74 (resistance to biotype 3), but the four cultivars are not similar to the resistant cultivar IR 36 varieties (resistance to biotype 2). Our research showed that both plant hair and protein banding patterns can not be used to identify the plant resistance.

Influence of cell-to-cell variability on spatial pattern formation

Many spatial patterns in biology arise through differentiation of selected cells within a tissue, which is regulated by a genetic network. This is specified by its structure, parameterisation and the noise on its components and reactions. The latter, in particular, is not well examined because it is rather difficult to trace. The authors use suitable local mathematical measures based on the Voronoi diagram of experimentally determined positions of epidermal plant hairs (trichomes) to examine the variability or noise in pattern formation. Although trichome initiation is a highly regulated process, the authors show that the experimentally observed trichome pattern is substantially disturbed by cell-to-cell variations. Using computer simulations, they find that the rates concerning the availability of the protein complex that triggers trichome formation plays a significant role in noise-induced variations of the pattern. The focus on the effects of cell noise yields further insights into pattern formation of trichomes. The authors expect that similar strategies can contribute to the understanding of other differentiation processes by elucidating the role of naturally occurring fluctuations in the concentration of cellular components or their properties.

Coconut Leaf Vermiwash as a Component of Organic Farming for Sustaining Soil Health and Fertility

Vermiwash, produced from actively vermicomposting substrates of coconut leaf + cowdung by the action of Eudrilus sp., has an alkaline pH, contains major and minor nutrients, growth hormones, humic acid and plant beneficial bacteria. Application of appropriately diluted coconut leaf vermiwash has shown to increase germination and seedling vigour index of cow pea and paddy seeds in laboratory bioassays. Field trials with cowpea, maize and bhendi (okra) in CPCRI farm showed its capacity to increase biomass and yield of the crops accompanied by enhanced soil microbial activities. Application of the vermiwash in red sandy loam soil produced an increase of 36% of fresh biomass weight, nodule numbers and 43% nodule fresh weight in cowpea at 1:10 dilution compared to control. In maize, increase in cob yield by 5-10%, fresh cob weight increase of 29-64% and in bhendi 22 to 33% increase in yield were recorded when vermiwash was applied at 1:5 dilution. To validate these results, field trials were taken up in farmers’ plots at Majal and Edneer area in Kasaragod. Bitter gourd and cowpea crops were taken up at Majal while amaranthus, cowpea and green chillies at Edneer. The soil type was sandy loam at Majal and lateritic at Edneer. Vermiwash produced at CPCRI was used as treatment along with farmers’ practice as control. The mode of application of vermiwash, dilution rates and intervals of application were carried out by the farmers as per recommendations. Observations on yield of the crops in vermiwash applied plots were recorded by the farmers. A yield of 75 kg cowpea and 200 kg bitter gourd at Majal; 55 kg amaranthus, 155 kg cowpea and 10kg dried chilli at Edneer plot were recorded from vermiwash applied plots.&#x0D; In both the places, observations indicated that application of vermiwash resulted in yield of crops on par or slightly lower than the plots that received regular fertilizer inputs as per farmers’ practice. However, in vermiwash treated plots, the farmers listed many other important points viz. healthy plant and root hair growth, lesser pest and disease damage, larger leaf size and deep leaf colour, longer ability of plants to stay without wilting in field as well as longer time of remaining fresh in case of amaranthus after harvesting, etc. The soil analysis also revealed that application of vermiwash in both types of soils increased the bacterial, fungal, actinomycetes, free-living nitrogen fixing, phosphate solubilzing and fluorescent pseudomonad population, and dehydrogenase, urease and phosphatase enzyme activities when compared to fertilizer treated plots. This clearly established the fact that vermiwash enhanced the soil fertility status for production of quality yield of agronomic and horticulture crops.

Three-Dimensional Hierarchical Structures for Fog Harvesting

Conventional fog-harvesting mechanisms are effectively pseudo-2D surface phenomena in terms of water droplet-plant interactions. In the case of the Cotula fallax plant, a unique hierarchical 3D arrangement formed by its leaves and the fine hairs covering them has been found to underpin the collection and retention of water droplets on the foliage for extended periods of time. The mechanisms of water capture and release as a function of the surface 3D structure and chemistry have been identified. Of particular note is that water is retained throughout the entirety of the plant and held within the foliage itself (rather than in localized regions). Individual plant hairs form matlike structures capable of supporting water droplets; these hairs wrap around water droplets in a 3D fashion to secure them via a fine nanoscale groove structure that prevents them from easily falling to the ground.

Differential regulation of a MYB transcription factor is correlated with transgenerational epigenetic inheritance of trichome density in Mimulus guttatus

• Epigenetic inheritance, transgenerational transmission of traits not proximally determined by DNA sequence, has been linked to transmission of chromatin modifications and gene regulation, which are known to be sensitive to environmental factors. Mimulus guttatus increases trichome (plant hair) density in response to simulated herbivore damage. Increased density is expressed in progeny even if progeny do not experience damage. To better understand epigenetic inheritance of trichome production, we tested the hypothesis that candidate gene expression states are inherited in response to parental damage. • Using M. guttatus recombinant inbred lines, offspring of leaf-damaged and control plants were raised without damage. Relative expression of candidate trichome development genes was measured in offspring. Line and parental damage effects on trichome density were measured. Associations between gene expression, trichome density, and response to parental damage were determined. • We identified M. guttatus MYB MIXTA-like 8 as a possible negative regulator of trichome development. We found that parental leaf damage induces down-regulation of MYB MIXTA-like 8 in progeny, which is associated with epigenetically inherited increased trichome density. • Our results link epigenetic transmission of an ecologically important trait with differential gene expression states - providing insight into a mechanism underlying environmentally induced 'soft inheritance'.

Membrane trafficking mediated by OsDRP2B is specific for cellulose biosynthesis

Increasing evidence has revealed that membrane trafficking is highly associated with cell wall metabolism. Factors involved in vesicle delivery, e.g. cytoskeleton and motor proteins, have showed regulatory effects on cell wall structure and components. However, little is known about the involvement of other trafficking components in distribution of cell wall-related compartments. Dynamins are important proteins functioning in membrane tubulation and vesiculation. Recently, we have reported characterization of the rice dynamin-related protein 2B (OsDRP2B). Mutation in OsDRP2B causes a significant reduction in cellulose content. Its association with the trans-Golgi network (TGN) and clathrin-coated vesicles and the reduced CESA4 abundance at the bc3 plasma membrane suggest that BC3/OsDRP2B is involved in the transport of essential elements for cellulose synthesis. Here, we provide additional evidence for BC3 subcellular localization via observing OsDRP2B-GFP in living root hairs of transgenic plants. Uronic acid and fractional composition analyses further confirm that the amount of arabinoxylan and other noncellulosic polysaccharides is increased in bc3. However, three putative xylan synthesis genes are down-regulated in mutant plant revealed by real-time PCR analysis. These results imply that compartments delivered by OsDRP2B are specifically responsible for cellulose biosynthesis.

Monolithically Integrated Two-Axis Microtensile Tester for the Mechanical Characterization of Microscopic Samples

This paper describes the first monolithically integrated two-axis microtensile tester and its application to the automated stiffness measurement of single epidermal plant cells. The tensile tester consists of a two-axis electrostatic actuator with integrated capacitive position sensors and a two-axis capacitive microforce sensor. It is fabricated using a bulk silicon microfabrication process. The actuation range is +/-16 m along both axes with a position resolution of 20 nm. The force sensor is capable of measuring forces up to +/-60 N with a resolution down to 60 nN. The position-feedback sensors as well as the force sensor are calibrated by direct comparison with reference standards. A complete uncertainty analysis through the entire calibration chain based on the Monte Carlo method is presented. The functionality of the tensile tester is demonstrated by the automated stiffness measurement of the elongated cells in plant hairs (trichomes) as a function of their size. This enables a quantitative understanding and a model-based simulation of plant growth based on actual measurement data.

Early signaling through the Arabidopsis pattern recognition receptors FLS2 and EFR involves Ca2+-associated opening of plasma membrane anion channels

The perception of microbes by plants involves highly conserved molecular signatures that are absent from the host and that are collectively referred to as microbe-associated molecular patterns (MAMPs). The Arabidopsis pattern recognition receptors FLAGELLIN-SENSING 2 (FLS2) and EF-Tu receptor (EFR) represent genetically well studied paradigms that mediate defense against bacterial pathogens. Stimulation of these receptors through their cognate ligands, bacterial flagellin or bacterial elongation factor Tu, leads to a defense response and ultimately to increased resistance. However, little is known about the early signaling pathway of these receptors. Here, we characterize this early response in situ, using an electrophysiological approach. In line with a release of negatively charged molecules, voltage recordings of microelectrode-impaled mesophyll cells and root hairs of Col-0 Arabidopsis plants revealed rapid, dose-dependent membrane potential depolarizations in response to either flg22 or elf18. Using ion-selective microelectrodes, pronounced anion currents were recorded upon application of flg22 and elf18, indicating that the signaling cascades initiated by each of the two receptors converge on the same plasma membrane ion channels. Combined calcium imaging and electrophysiological measurements revealed that the depolarization was superimposed by an increase in cytosolic calcium that was indispensable for depolarization. NADPH oxidase mutants were still depolarized upon elicitor stimulation, suggesting a reactive oxygen species-independent membrane potential response. Furthermore, electrical signaling in response to either flg22 or elf 18 critically depends on the activity of the FLS2-associated receptor-like kinase BAK1, suggesting that activation of FLS2 and EFR lead to BAK1-dependent, calcium-associated plasma membrane anion channel opening as an initial step in the pathogen defense pathway.

Analysis of QTLs for the Trichome Density on the Upper and Downer Surface of Leaf Blade in Soybean [ Glycine max (L.) Merr.

Trichomes (plant hairs) are present on nearly all land plants and are known to play important roles in plant protection, specifically against insect herbivory, drought, and UV radiation. The identification of quantitative trait loci (QTL) associated with trichome density should help to interpret the molecular genetic mechanism of soybean trichome density. 184 recombinant inbred lines (RILs), derived from a cross between soybean cultivars Kefeng 1 and Nannong 1138-2 were used as segregating population for evaluation of TDU (trichome density on the upper surface of leaf blade) and TDD (trichome density on the downer surface of leaf blade). A total of 15 QTL were detected on molecular linkage groups (MLG) A2, D1a, D1b, E and H by composite interval mapping (CIM) and among all the QTL, qtuA2-1, qtuD1a-1, qtuD1b-2, qtuH-2 qtuE-1, qtdD1b-2, and qtdH-2 were affirmed by multiple interval mapping (MIM). The contribution of phenotypic variance of qtuH-2 was 31.81 and 29.4% by CIM and MIM, respectively, suggesting it might be major gene Ps loci. Only 10 pairs of main QTL interactions for TDU were detected, explained a range of 0.2-5.1% of phenotypic variations for each pair for a total of 22.8%. The QTL on MLG D1b affecting trichome density were mapped near to Rsc-7 conditioning resistance to SMV (soybean mosaic virus). This study showed that the genetic mechanism of trichome density was the mixed major gene and polygene inheritance, and also suggested that the causal nature between trichome density and other agronomic traits.

XuvTools: free, fast and reliable stitching of large 3D datasets

Current biomedical research increasingly requires imaging large and thick 3D structures at high resolution. Prominent examples are the tracking of fine filaments over long distances in brain slices, or the localization of gene expression or cell migration in whole animals like Caenorhabditis elegans or zebrafish. To obtain both high resolution and a large field of view (FOV), a combination of multiple recordings ('tiles') is one of the options. Although hardware solutions exist for fast and reproducible acquisition of multiple 3D tiles, generic software solutions are missing to assemble ('stitch') these tiles quickly and accurately. In this paper, we present a framework that achieves fully automated recombination of tiles recorded at arbitrary positions in 3D space, as long as some small overlap between tiles is provided. A fully automated 3D correlation between all tiles is achieved such that no manual interaction or prior knowledge about tile positions is needed. We use (1) phase-only correlation in a multi-scale approach to estimate the coarse positions, (2) normalized cross-correlation of small patches extracted at salient points to obtain the precise matches, (3) find the globally optimal placement for all tiles by a singular value decomposition and (4) accomplish a nearly seamless stitching by a bleaching correction at the tile borders. If the dataset contains multiple channels, all channels are used to obtain the best matches between tiles. For speedup we employ a heuristic method to prune unneeded correlations, and compute all correlations via the fast Fourier transform (FFT), thereby achieving very good runtime performance. We demonstrate the successful application of the proposed framework to a wide range of different datasets from whole zebrafish embryos and C. elegans, mouse and rat brain slices and fine plant hairs (trichome). Further, we compare our stitching results to those of other commercially and freely available software solutions. The algorithms presented are being made available freely as an open source toolset 'XuvTools' at the corresponding author's website (http://lmb.informatik.uni-freiburg.de/people/ronneber), licensed under the GNU General Public License (GPL) v2. Binaries are provided for Linux and Microsoft Windows. The toolset is written in templated C++, such that it can operate on datasets with any bit-depth. Due to the consequent use of 64bit addressing, stacks of arbitrary size (i.e. larger than 4 GB) can be stitched. The runtime on a standard desktop computer is in the range of a few minutes. A user friendly interface for advanced manual interaction and visualization is also available.