Young Roots Research Articles

Growth and aluminum tolerance of maize roots mediated by auxin- and cytokinin-producing Bacillus toyonensis requires polar auxin transport

Plant Growth Promotion Rhizobacteria (PGPR) control plant development by modulation of their phytohormone activities. To probe how PGPR trigger plant growth and mitigate stress induced by aluminum (Al), the beneficial effect of Bacillus toyonensis strain Bt04 (Bt04), isolated from the Algerian Sahara rhizosphere, on maize roots was assessed. Our results revealed that the strain Bt04 is producing indole-3-acetic acid (IAA) both endogenously and from tryptophan (Trp). Surprisingly, the production of another endogenous auxin, a non-indole phenylacetic acid (PAA), was found at higher concentrations than IAA. Additionally, the production of cytokinins (CKs) by Bt04 has been demonstrated. Inoculation with Bt04 resulted in a promotion of maize growth and an enhancement of root development under aluminium (Al) toxicity condition. Importantly, Bt04 reduced Al accumulation in the young maize roots. Moreover, we could demonstrate that Bt04 itself exhibits tolerance to high concentrations of AlCl3. Bt04 might exert its growth promoting effect partially by increasing protection against oxidative stress since bacterial treatment reduced lipid peroxidation in maize seedlings under Al toxicity. To investigate a possible mechanism of this growth induction of maize seedlings we treated them under control and stress conditions with auxin transport inhibitors and demonstrated that the auxin transport pathway is needed for the Al induced stress response after inoculation with the PGPR.

Arabidopsis Lectin EULS3 Is Involved in ABA Signaling in Roots.

The Arabidopsis thaliana lectin ArathEULS3 is upregulated in particular stress conditions and upon abscisic acid (ABA) treatment. ABA is a plant hormone important for plant growth and stress responses. During stress ABA is perceived by PYR/PYL/RCAR receptors, inhibiting protein phosphatases PP2Cs thereby enabling SNRK2s kinases to start downstream phosphorylation cascades and signaling. PYL9, one of the ABA receptors was identified as an interacting partner for ArathEULS3. Promoter::GUS activity studies revealed the expression of ArathEULS3 in the central root cylinder and the cells flanking young lateral root primordia, and showed enhanced expression in root tips after ABA treatment. Transcript levels for ArathEULS3 increased after exposure to ABA and osmotic treatments. ArathEULS3 CRISPR KO mutants served as a tool to expand the knowledge on the role of ArathEULS3 in plant development. KO lines revealed a longer root system compared to WT plants, and showed reduced sensitivity to ABA, salt, and osmotic conditions. Additionally it was noted that the KO mutants had more emerged lateral roots when grown in high osmotic conditions. Together these data suggest that ArathEULS3 may be an important player in ABA responses in roots.

Transforming Growth Factor Beta 1 Distribution and Content in the Root Dentin of Young Mature and Immature Human Premolars

IntroductionTransforming growth factor beta 1 (TGF-β1) is a key morphogen in regenerative endodontics; yet, its location within the hard tissue phase of dentin and its availability in mature roots have not been fully elucidated. MethodsYoung mature (n = 8) and immature (n = 11) roots from sound premolars were obtained from 13 orthodontic patients aged 17 ± 1 and 12 ± 1 years, respectively. Roots were cleaned of organic remnants in 5% sodium hypochlorite. The width of the minor foramen was measured using a digital microscope. TGF-β1 distribution was assessed in 3 roots per group by immunostaining combined with confocal laser scanning microscopy. The root dentin of the remaining 13 roots was powdered and decalcified in 17% EDTA to determine the overall levels of hard tissue–embedded TGF-β1 by enzyme-linked immunosorbent assay. Data were compared between groups using the Student t test (α = .05). ResultsThe minor foramen was 168 ± 49 μm versus 557 ± 295 μm in mature compared with immature roots (P < .05). TGF-β1 was highly stainable toward the pulp space in both groups. It was clearly associated with peritubular dentin and apparently absent in nontubular outer dentin. TGF-β1 content was 115 ± 31 pg and 74 ± 35 pg/100 mg mature versus immature root dentin, respectively (P > .05). ConclusionsTGF-β1 is deposited into the peritubular dentin. It should be possible to release this molecule in regenerative endodontic procedures from young mature roots as well as immature roots.

Structural features and contribution of belowground buds to conservation of Fabaceae species in a seasonally dry Neotropical environment

Resprouting from belowground buds is an important mechanism to increase aboveground branching. This trait is particularly frequent in various members of Fabaceae. However, there are scant anatomical studies on belowground buds including information about their location in the plant body in these species. Herein we examined the anatomy of belowground buds and organs that support these buds in herbaceous and woody Fabaceae species. Adventitious buds located in the root-shoot transition zone (root crown) were the predominant type of belowground buds in herbaceous and subshrubby species. Moreover, some woody species showed lateral roots with root buds growing near the soil surface. The root structure was confirmed by the centripetal maturation of the primary xylem (exarch xylem). Anatomical analyses of Cenostigma pluviosum and Senna pilifera roots revealed numerous reparative buds that develop from calli. Reparative buds were formed only after injury to root tissues or shoot removal. On the other hand, the roots of Machaerium eriocarpum and Muellera nudiflora showed additional buds with bud traces connected to the primary xylem. Additional buds were found in uninjured young roots and in root segments that were kept in a greenhouse condition. Our findings show that the species examined of Fabaceae are able to resprout from adventitious buds located in roots and root crowns. This trait seems to be advantageous for conservation of these species in the Brazilian Chaco, which is characterised by dry seasons associated with frost and extensive cattle raising.

Laterals take it better \u2013 Emerging and young lateral roots survive lethal salinity longer than the primary root in Arabidopsis

Plant responses to salinity have been extensively studied over the last decades. Despite the vast accumulated knowledge, the ways Arabidopsis lateral roots (LR) cope with lethal salinity has not been fully resolved. Here we compared the primary root (PR) and the LR responses during events leading to lethal salinity (NaCl 200 mM) in Arabidopsis. We found that the PR and young LR responded differently to lethal salinity: While the PR died, emerging and young LR’s remained strikingly viable. Moreover, “age acquired salt tolerance” (AAST) was observed in the PR. During the 2 days after germination (DAG) the PR was highly sensitive, but at 8 DAG there was a significant increase in the PR cell survival. Nevertheless, the young LR exhibited an opposite pattern and completely lost its salinity tolerance, as it elongated beyond 400 µm. Examination of several cell death signatures investigated in the young LR showed no signs of an active programmed cell death (PCD) during lethal salinity. However, Autophagic PCD (A-PCD) but not apoptosis-like PCD (AL-PCD) was found to be activated in the PR during the high salinity conditions. We further found that salinity induced NADPH oxidase activated ROS, which were more highly distributed in the young LR compared to the PR, is required for the improved viability of the LR during lethal salinity conditions. Our data demonstrated a position-dependent resistance of Arabidopsis young LR to high salinity. This response can lead to identification of novel salt stress coping mechanisms needed by agriculture during the soil salinization challenge.

First Report of Sudden Death of Clove Trees Caused by Cytospora eugeniae in Brazil

Clove (Syzygium aromaticum (L.) Merr. & Perry) is grown worldwide for its aromatic flower buds, which are used as a spice and pharmaceutical ingredient. It is a large tree that can reach 15 m in height and live for over 100 years. In 2017, the disease was observed in clove plantations in northeastern Brazil, lower south region of Bahia State (13°21′27.11″S 39°8′25.19″E). Observed tree losses ranged from 10% on some farms to 90% on others. This region is the main clove producing area of Brazil. The losses were attributed to “sudden death,” first reported by Nutman and Roberts (1953) to be devastating clove plantations in the Zanzibar Archipelago of Tanzania. There, the causal agent was identified as Valsa eugeniae Nutman & Roberts, which was renamed Cytospora eugeniae (Nutman & F.M. Roberts) G. C. Adams & Rossman (Rossman et al. 2015). In Brazil, as in Tanzania, symptom progression on affected trees consisted of a sudden shedding of green leaves and wilting of the remaining leaves, which acquired a reddish-brown color while still in the tree. Concurrent with defoliation, the young roots on affected trees exhibited decay, and the wood just under the bark on tree trunks developed an intense yellow color. Canopy symptoms (rapid or delayed leaf fall) varied, depending on air humidity during disease onset. On the affected clove trees in Brazil, we observed ascostromata (n = 30) typical of C. eugeniae immersed in the bark, valsoid, with black perithecia commonly in groups of 4 to 12, occasionally found alone or in groups of 50 or more. Perithecia globose, 240 to 335 µm, with long ostioles of 600 to 4,000 µm (n = 50) above surfaces; asci sessile, unitunicate, subclavate, apex rounded, 8-spored, 16 to 21 (19) × 3.6 to 5.7 (4.5) µm (n = 50); ascospores hyaline, allantoid, aseptate, 4.5 to 6.3 (5.2) × 1.4 to 2.2 (1.9) µm (n = 50). We isolated C. eugeniae from symptomatic stem and root fragments, collected from clove trees affected by sudden death. The tissue pieces, surface sterilized and rinsed in sterile water, were cultured on PDA and incubated at 25°C with a 12-h photoperiod. Subcultures of the fungus on PDA produced pycnidia dark, unilocular, globose or ovoid, 250 to 330 µm in diameter (n = 50); conidiophores hyaline, branched, 10 to 40 × 1 to 2 µm; conidiogenous cells enteroblastic, phialidic, 7 to 18 × 1 to 1.8 µm; conidia hyaline, allantoid, aseptate, 2 to 4 (3.1) × 0.7 to 1.6 (1.1) µm. Morphological identification was confirmed by DNA sequencing. The DNA was extracted from pure culture and ITS sequences were obtained using ITS1/ITS4 primers (White et al. 1990). The sequence obtained (527 bp) (GenBank MN460826) was 100% similar to C. eugeniae (KY051813, KY051811, KY051810). For inoculation tests, a 20 µl aliquot of a suspension of six isolates from pathogen (10⁶ conidia/ml) was pipetted on a wound (1 cm long) made with a knife in the bark of clove stem fragments (20 cm long, 2 to 4 cm diam.). Distilled water only and non-pathogen fungus (Phomopsis sp.) were used as negative controls. The fragments were incubated in a humid chamber at 25°C. Each treatment was replicated six times. Fifteen days after inoculation, all isolates produced lesions on the inoculated fragments (mean infected area 15.33 cm²), while controls showed no symptoms. Cultures reisolated from lesions exhibited morphological characteristics identical to those of C. eugeniae. To our knowledge, this is the first report of C. eugeniae causing sudden death disease in Brazil. Elucidation of the cause of sudden death may provide a foundation for development of management strategies for the disease.

Anatomy of Balkan Amphoricarpos Vis. (Cardueae, Asteraceae) taxa

Anatomical analysis of root, rhizome, leaf, peduncle and inflorescences has been conducted on Balkan Amphoricarpos taxa, A. neumayerianus (Vis.) Greuter subsp. neumayerianus, A. neumayerianus subsp. murbeckii Bosnjak, A. autariatus Blecic & Mayer subsp. autariatus and A. autariatus subsp. bertisceus Blecic & Mayer using light microscopy (LM) and scanning electron microscopy (SEM), in order to examine the anatomical traits of this genus for the first time. All taxa show similar features. Young adventitious roots share a typical structure. Sclerenchyma fibers are present in the center of older root. On the rhizome cross sections, secondary tissues are noticed with wide parenchyma rays which interrupt a-well developed xylem. Rhizomes show eccentric growth. The leaf blade is amphistomatous, with dorsiventral structure. Crystal druses are found in leaf epidermal and mesophyll cells. The peduncle cross sections is characterized by more or less polygonal shape with medullary collateral vascular bundles arranged in a circle, and a few of them outside of the circle, toward to cortex region. Secretory canals are absent. Involucral bracts and paleae are characterised by the presence of multilayer sclerenchyma in the mesophyll. Inflorescence anatomy shows structures commonly described for Asteraceae members. Densely distributed vermiform (lanate) and glandular biseriate trichomes are present on the peduncle and on both leaf sides, but much more on the abaxial. Anatomical uniformity indicates very close relationships between examined taxa regarding conserve nature of the genome of the genus. Obtained characters contribute to the knowledge of the genus Amphoricarpos anatomy.

Identification of Regulatory Networks and Hub Genes Controlling Nitrogen Uptake in Tea Plants [Camellia sinensis (L.) O. Kuntze

Nitrogen (N) uptake, as the first step of N metabolism, is a key limiting factor for plant growth. To understand the gene expression networks that control N absorption and metabolism in tea plants, we analyzed transcriptomes in the young roots of two groups of tea plants with significantly different growth rates under different N treatments (0, 0.2, and 2 mM). Using pairwise comparisons and weighted gene co-expression network analyses (WGCNA), we successfully constructed 16 co-expression modules. Among them, a specific module (turquoise) that substantially responded to the low N treatment was identified. Based on KEGG analysis, the relative genes that enriched in the "N metabolism" pathways were used to construct gene co-expression networks of N metabolism. Finally, a high-affinity ammonium (NH4+) transporter designated CsAMT1.2 was identified as a hub gene in the N metabolism network in tea plant roots and the gene expression could be highly induced by N resupply. The gene functional analysis revealed that CsAMT1.2 could make functional complementation of MEP1, MEP2, and MEP3 genes in 31019b yeast cells and improve NH4+ uptake rate in 31019b at low NH4+ level. Thus, CsAMT1.2 was a key gene controlling N uptake in tea plants and might play a vital role in promoting NH4+ uptake from the environment in tea roots. This study provided a useful foundation for improving the NUE in tea plantations.

Зависимость дыхания стволов дуба разных классов роста от условий окружающей среды

Зависимость дыхания стволов дуба разных классов роста от условий окружающей среды

Characterization of root traits for improvement of spring wheat in the Pacific Northwest

AbstractUnderstanding the genetic basis of root traits provides essential information on a largely untapped resource for crop improvement, as roots are instrumental for the uptake of water and nutrients. However, breeding for improved root traits is challenging due to laborious and time‐consuming root phenotyping in soil. Our studies sought to uncover spatiotemporal root‐growth dynamics of mature plant root systems in five spring wheat (Triticum aestivum L.) cultivars, Louise, Alpowa, Hollis, Drysdale, and Dharwar Dry, and a facultative spring landrace, AUS28451 using the in situ minirhizotron technique. The 2‐yr greenhouse study revealed that the root system grows rapidly after early node elongation to gain maximum size during anthesis, after which root growth slows and transitions to senescence. We were able to detect quantifiable differences among wheat cultivars in root traits in both 5‐d old seedlings and root systems at anthesis. Furthermore, the positive correlation of the observed root traits with grain yield and the consistency in root traits observed using minirhizotrons and through extraction of young and mature root systems has reinforced the experimental results. A negative correlation was found between root number, area, and length and root diameter. We found that the spring wheat cultivars, AUS28451, Dharwar Dry, and Alpowa, had increased root number, area, and length, but also increased time to heading. The results from this study can be further leveraged to screen breeding lines for root traits of interest, as well as assess the heritability of root traits for dryland farming in the inland Pacific Northwest.

Biological control of symphylid pests in a commercial chrysanthemum (Dendranthema grandiflora) crop using the fungus Purpureocillium lilacinum, strain UdeA0106

The symphylids, also known as garden centipedes or pseudocentipedes, are soil-dwelling arthropods of the class Symphyla. They affect diverse crops worldwide due to the consumption of young roots and seedlings. This study presents the effectiveness of the fungus Purpureocillium lilacinum (strain UdeA0106) to reduce the symphylid population under commercial greenhouse conditions. The results showed that this fungus strain could reduce symphylid density by 70.6%. It also demonstrated that a high concentration of strain UdeA0106 helped to recover chrysanthemum (Dendranthema grandifIora) crops infested with symphylid. The results shown in this paper are the first evidence of effective biological control of symphylids pest in a commercial fIower plantation, representing the potential of P. lilacinum strain UdeA0106 as a biological control agent.

Ecology and Seasonal Development of Ranunculus nipponicus Nakai (Batrachium, Ranunculaceae) in Nonfreezing Watercourses on the Northern Coast of the Sea of Okhotsk

The ecology and seasonal development of Ranunculus nipponicus in nonfreezing watercourses on the northern coast of the Sea of Okhotsk (59° N) have been studied. Year-round vegetation and flowering without the formation of a resting stage of the water crowfoot has been reported for the first time for the territory of Russian Federation. During all months of the year, the shoot growth, the formation of young roots, buds, and cleistogamous flowers are observed at an average monthly water temperature of +0.1°C to +5.8°C. The most intensive formation of young roots takes place in February–March and the underwater flowers appear en masse in late March–early April; neither phenomena are associated with an increase in water temperature. Cleistogamous flowering rarely leads to seed ripening, possibly due to a water temperature that is too low.

Response of Chamecytisus palmensis to drought stress induced by polyethylene glycol during germination

Seed germination and subsequent changes in Chamecytisus palmensis were studied under water limiting conditions, imposed by increasing concentrations of polyethylene glycol (PEG-6000) (0, 5, 10, 15, 20, 25, and 30%). Six water stress conditions (< −0.20, −0.20, −0.40, −0.60, −0.8, and −1.20 MPa) were created in the laboratory in a completely randomized design. The results showed that PEG-simulated drought stress had an inhibitory and lag effect on seed germination of C. palmensis. Seed germination was completely inhibited under the drought stress of 30% (−1.20 MPa). Similar to the seed germination, the growth of radicles and hypocotyls after seed germination was also restricted by PEG-simulated drought stress, especially when water potential was lower than −0.12 MPa (25%). In the same way, the ratio of radicles and hypocotyls significantly decreased with the increase of PEG concentrations, demonstrating strong adaptability to drought stress. Moreover, the decline of radicles and hypocotyls lead to a decrease in the number of root hairs. This would seriously affect the water absorption ability of the young roots. It was concluded that drought stress might be one of the causes for obstructed natural regeneration of C. palmensis plantations on sandy land.

Preceding crop and tillage system affect winter survival of wheat and the fungal communities on young wheat roots and in soil.

ABSTRACTAgricultural practices like tillage and cropping sequence have profound influence on soil-living and plant-associated fungi, and thereby on plant growth. In a field experiment, we studied the effects of preceding crop and tillage on fungal communities in the soil and on young winter wheat roots in relation to plant winter survival and grain yield. We hypothesized that plant performance and fungal communities (described by amplicon sequencing) differ depending on tillage system and preceding crop; that the effect of preceding crop differs depending on tillage system, and that differences in fungal communities are reflected in plant performance. In line with our hypotheses, effects of preceding crop on plant growth and fungal communities on plant roots and in soil were more pronounced under non-inversion tillage than under inversion tillage (ploughing). Fungal communities on plant roots in treatments with low winter survival were different from those with better survival. In soil, several fungal OTUs (operational taxonomic units) differed significantly between tillage systems. OTUs representing putative plant pathogens were either more abundant (Parastagonospora sp._27) or less abundant (Fusarium culmorum/graminearum_5) after non-inversion tillage. Our findings highlight the influence of cultural practices on fungal communities and thereby on plant health and yield.

Two mechanisms regulate directional cell growth in Arabidopsis lateral roots.

Morphogenesis in plants depends critically on directional (anisotropic) growth. This occurs principally perpendicular to the net orientation of cellulose microfibrils (CMFs), which is in turn controlled by cortical microtubules (CMTs). In young lateral roots of Arabidopsis thaliana, growth anisotropy also depends on RAB-A5c, a plant-specific small GTPase that specifies a membrane trafficking pathway to the geometric edges of cells. Here we investigate the functional relationship between structural anisotropy at faces and RAB-A5c activity at edges during lateral root development. We show that surprisingly, inhibition of RAB-A5c function is associated with increased CMT/CMF anisotropy. We present genetic, pharmacological, and modelling evidence that this increase in CMT/CMF anisotropy partially compensates for loss of an independent RAB-A5c-mediated mechanism that maintains anisotropic growth in meristematic cells. We show that RAB-A5c associates with CMTs at cell edges, indicating that CMTs act as an integration point for both mechanisms controlling cellular growth anisotropy in lateral roots.

Mechanical properties and structure-function trade-offs in secondary xylem of young roots and stems.

Bending and torsional properties of young roots and stems were measured in nine woody angiosperms. The variation in mechanical parameters was correlated to wood anatomical traits and analysed with respect to the other two competing functions of xylem (namely storage and hydraulics). Compared with stems, roots exhibited five times greater flexibility in bending and two times greater flexibility in torsion. Lower values of structural bending and structural torsional moduli (Estr and Gstr, respectively) of roots compared with stems were associated with the presence of thicker bark and a greater size of xylem cells. Across species, Estr and Gstr were correlated with wood density, which was mainly driven by the wall thickness to lumen area ratio of fibres. Higher fractions of parenchyma did not translate directly into a lower wood density and reduced mechanical stiffness in spite of parenchyma cells having thinner, and in some cases less lignified, cell walls than fibres. The presence of wide, partially non-lignified rays contributed to low values of Estr and Gstr in Clematis vitalba. Overall, our results demonstrate that higher demands for mechanical stability in self-supporting stems put a major constraint on xylem structure, whereas root xylem can be designed with a greater emphasis on both storage and hydraulic functions.

Expression and functional characterization of sugar beet phosphoethanolamine/phosphocholine phosphatase under salt stress

Choline is a vital metabolite in plant and synthesized from phosphocholine by phosphocholine phosphatase. The Arabidopsis At1g17710 was identified as the first plant gene encoding the phosphatase for both phosphoethanolamine and phosphocholine (PECP) with much higher catalytic efficiency (>10-fold) for former. In betaine accumulating plants, choline is further required for betaine synthesis. In this report, we found three putative PECP genes in sugar beet, betaine accumulating plants. Two genes encode the proteins of 274 amino acid residues and designated as BvPECP1S and BvPECP2S. Another gene encodes the 331 amino acid protein (BvPECP2L) consisted of BvPECP2S with extra C-terminal amino acid. Enzymatic assays of BvPECP1S revealed that BvPECP1S exhibited the phosphatase activity for both phosphoethanolamine and phosphocholine with higher affinity (>1.8-fold) and catalytic efficiency (>2.64-fold) for phosphocholine. BvPECP2L exhibited low activity. RT-PCR experiments for BvPECP1S showed the increased expression in young leaf and root tip under salt-stress whereas the increased expression in all organs under phosphate deficiency. The expression level of BvPECP2L in salt stressed young leaf and root tip was induced by phosphate deficient. Physiological roles of BvPECP1S and BvPECP2L for the betaine synthesis were discussed.

PHYTOHORMONAL REGULATORY MECHANISM OF THE ONTOGENESIS OF HETERODERIDES’ ACTIVATION AND SYNCHRONIZATION

Studies using the developed device confirmed the attractive properties of the aquatic extracts of host plants, as well as the high trophic receptivity of the invasive larvae of cyst nematodes. The greatest stimulation of the release and active migration of larvae from cysts was observed when phytoncids were introduced by cultivated host plants at a distance of 2.5–5 cm from the object of study at an optimal humidity of 60–70% of the total soil moisture content. At the same time, the aqueous extracts of the roots of the initial phases of plant growth and development compared to the extracts of the subsequent organogenesis phases were the most attractive. We believe that the larvae react most to the increased content of phytohormones, cytokinins, because their synthesis in comparison with other growth activators mainly occurs in the root system of plants. Nematode isolation of enzymes in plant tissue causes a high content of phytohormones, which are catalysts for the formation of new young roots, thereby providing optimal conditions for the invasion and development of next-generation larvae. Certain stimulating effect was also shown by extracts from other plant organs, which indicates the integrity of the flow of all physiological processes in the plant organism. Due to the genetically fixed mechanism of activation and suspension of physiological processes, a clear synchronization of the ontogenesis of cyst nematodes in accordance with the organogenesis of host plants has been noted. Since the development of heteroderides occurs only in one plant populated by them, sedentary phytoparasites react sensitively to changes in the biochemical composition of the plant organism, due to biological aging or adverse factors of different nature, causing their pathology. The perennial cyclical nature of the development of sedimentary nematodes in accordance with the organogenesis of typical host plants caused the formation of their population adaptation.

Lateral Root and Nodule Transcriptomes of Soybean

Symbiotic legume nodules and lateral roots arise away from the root meristem via dedifferentiation events. While these organs share some morphological and developmental similarities, whether legume nodules are modified lateral roots is an open question. We dissected emerging nodules, mature nodules, emerging lateral roots and young lateral roots, and constructed strand-specific RNA sequencing (RNAseq) libraries using polyA-enriched RNA preparations. Root sections above and below these organs, devoid of any lateral organs, were used to construct respective control tissue libraries. High sequence quality, predominant mapping to coding sequences, and consistency between replicates indicated that the RNAseq libraries were of a very high quality. We identified genes enriched in emerging nodules, mature nodules, emerging lateral roots and young lateral roots in soybean by comparing global gene expression profiles between each of these organs and adjacent root segments. Potential uses for this high quality transcriptome data set include generation of global gene regulatory networks to identify key regulators; metabolic pathway analyses and comparative analyses of key gene families to discover organ-specific biological processes; and identification of organ-specific alternate spliced transcripts. When combined with other similar datasets, especially from leguminous plants, these analyses can help answer questions on the evolutionary origins of root nodules and relationships between the development of different plant lateral organs.

William Cowper, l’homme-tronc

L’image que l’on retient communément de William Cowper est celle d’un homme faible et fragile psychologiquement, voire d’un « poltron » (selon W. Hazlitt) qui « craignait de croire en lui-même ». Pourtant, cette supposée infirmité tend à estomper la vigueur et l’originalité de son œuvre. Cet article vise à réévaluer la poésie de Cowper en traitant principalement de sa passion pour la vie végétale. En tant qu’organismes vivants dont la croissance spontanée les déploie en formes naturelles, arbres centenaires et jeunes pousses, racines, fleurs et feuilles, et même concombres (dont la phallicité est explicite) offrirent à Cowper les métaphores heureuses d’un corps textuel vivifié. Tous témoignent des intuitions créatrices du poète et de sa remarquable capacité à faire évoluer la langue poétique dans sa quête de ravissement intellectuel et de jouissance physique.