Enhancing maize's nitrogen-fixing potential through ZmSBT3, a gene suppressing mucilage secretion.

Maize (Zea mays) requires substantial amounts of nitrogen, posing a challenge for its cultivation. Recent work discovered that some ancient Mexican maize landraces harbored diazotrophic bacteria in mucilage secreted by their aerial roots. To see if this trait is retained in modern maize, we conducted a field study of aerial root mucilage (ARM) in 258 inbred lines. We observed that ARM secretion is common in modern maize, but the amount significantly varies, and only a few lines have retained the nitrogen-fixing traits found in ancient landraces. The mucilage of the high-ARM inbred line HN5-724 had high nitrogen-fixing enzyme activity and abundant diazotrophic bacteria. Our genome-wide association study identified 17 candidate genes associated with ARM across three environments. Knockouts of one candidate gene, the subtilase family gene ZmSBT3, confirmed that it negatively regulates ARM secretion. Notably, the ZmSBT3 knockout lines had increased biomass and total nitrogen accumulation under nitrogen-free culture conditions. High ARM was associated with three ZmSBT3 haplotypes that were gradually lost during maize domestication, being retained in only a few modern inbred lines such as HN5-724. In summary, our results identify ZmSBT3 as a potential tool for enhancing ARM, and thus nitrogen fixation, in maize.

Mucilage secretion by aerial roots in sorghum (Sorghum bicolor): sugar profile, genetic diversity, GWAS and transcriptomic analysis.

Aerial root mucilage can enhance nitrogen fixation by providing sugar and low oxygen environment to the rhizosphere microbiome in Sierra Mixe maize. Aerial root mucilage has long been documented in sorghum (Sorghum bicolor), but little is known about the biological significance, genotypic variation, and genetic regulation of this biological process. In the present study, we found that a large variation of mucilage secretion capacity existed in a sorghum panel consisting of 146 accessions. Mucilage secretion occurred primarily in young aerial roots under adequately humid conditions but decreased or stopped in mature long aerial roots or under dry conditions. The main components of the mucilage-soluble were glucose and fructose, as revealed by sugar profiling of cultivated and wild sorghum. The mucilage secretion capacity of landrace grain sorghum was significantly higher than that of wild sorghum. Transcriptome analysis revealed that 1844 genes were upregulated and 2617 genes were downregulated in mucilage secreting roots. Amongst these 4461 differentially expressed genes, 82 genes belonged to glycosyltransferases and glucuronidation pathways. Sobic.010G120200, encoding a UDP-glycosyltransferase, was identified by both GWAS and transcriptome analysis as a candidate gene, which may be involved in the regulation of mucilage secretion in sorghum through a negative regulatory mechanism.

Developmental Characteristics and Auxin Response of Epiphytic Root in Dendrobium catenatum.

Dendrobium catenatum, a traditional precious Chinese herbal medicine, belongs to epiphytic orchids. Its special life mode leads to the specialization of roots, but there is a lack of systematic research. The aerial root in D. catenatum displays diverse unique biological characteristics, and it initially originates from the opposite pole of the shoot meristem within the protocorm. The root development of D. catenatum is not only regulated by internal cues but also adjusts accordingly with the change in growth environments. D. catenatum root is highly tolerant to auxin, which may be closely related to its epiphytic life. Exogenous auxin treatment has dual effects on D. catenatum roots: relatively low concentration promotes root elongation, which is related to the induced expression of cell wall synthesis genes; excessive concentration inhibits the differentiation of velamen and exodermis and promotes the overproliferation of cortical cells, which is related to the significant upregulation of WOX11-WOX5 regeneration pathway genes and cell division regulatory genes. Overexpression of D. catenatum WOX12 (DcWOX12) in Arabidopsis inhibits cell and organ differentiation, but induces cell dedifferentiation and callus production. Therefore, DcWOX12 not only retains the characteristics of ancestors as stem cell regulators, but also obtains stronger cell fate transformation ability than homologous genes of other species. These findings suggest that the aerial root of D. catenatum evolves special structure and developmental characteristics to adapt to epiphytic life, providing insight into ideal root structure breeding of simulated natural cultivation in D. catenatum and a novel target gene for improving the efficiency of monocot plant transformation.

Genomes of the Banyan Tree and Pollinator Wasp Provide Insights into Fig-Wasp Coevolution.

Banyan trees are distinguished by their extraordinary aerial roots. The Ficus genus includes species that have evolved a species-specific mutualism system with wasp pollinators. We sequenced genomes of the Chinese banyan tree, F. microcarpa, and a species lacking aerial roots, F. hispida, and one wasp genome coevolving with F. microcarpa, Eupristina verticillata. Comparative analysis of the two Ficus genomes revealed dynamic karyotype variation associated with adaptive evolution. Copy number expansion of auxin-related genes from duplications and elevated auxin production are associated with aerial root development in F. microcarpa. A male-specific AGAMOUS paralog, FhAG2, was identified as a candidate gene for sex determination in F. hispida. Population genomic analyses of Ficus species revealed genomic signatures of morphological and physiological coadaptation with their pollinators involving terpenoid- and benzenoid-derived compounds. These three genomes offer insights into and genomic resources for investigating the geneses of aerial roots, monoecy and dioecy, and codiversification in a symbiotic system.

An Efficient Method for In Vitro Shoot-Tip Culture and Sporophyte Production Using Selaginella martensii Spring Sporophyte.

Selaginella martensii, an evergreen perennial fern that is native to South America and New Zealand, is named "frosty fern" because of its beautiful white-colored leaves and it is used as an ornamental plant. Efficient propagation methods for this species have not been developed. We aimed to develop an efficient propagation method for S. martensii through in vitro culture. We investigated culture conditions that are suitable for shoot-tip proliferation and growth. The optimum shoot-tip culture conditions were determined while using Murashige and Skoog (MS) medium (quarter, half, full, or double strength) and macronutrients (sucrose and two nitrogen sources) at various concentrations. In MS medium, the shoot tips formed a maximum of 6.77 nodes per explant, and each node formed two new shoot tips (i.e., 26 or 64 shoot tips). When using branching segments containing an angle meristem, the shoot-to-rhizophore formation ratio could be controlled by medium supplementation with plant-growth regulators. Sporophytes that were grown from shoot tips in vitro were acclimated in ex vitro soil conditions and successfully survived in the greenhouse. Numerous shoot tips could be obtained from in vitro-grown sporophytes and be proliferated ex vitro to produce a large number of plants. This method provides a way of shortening the time that is required for producing a large stock of S. martensii planting material.

Adsorption properties and mechanisms of novel biomaterials from banyan aerial roots via simple modification for ciprofloxacin removal.

The study investigated ciprofloxacin (CIP) adsorption capacity of the novel biomaterials prepared from banyan aerial roots by simple thermochemical modification. Pretreated banyan aerial root fibers were modified with a green reagent citric acid (1 M) at 90, 120 and 150 °C, which enhanced the fiber adsorption capacity revealed by characterization and adsorption tests. Several characterization methods were applied to exploring the surface morphologies and physicochemical properties of unmodified banyan aerial roots (UBARs) and modified banyan aerial roots (T-MBARs, T stands for the modification temperature). Based on SEM images and N2 adsorption/desorption isotherms, the modification resulted in decrease of the specific surface area owing to cellulose molecular linking. In that case, the improved CIP adsorption of MBARs might be attributed to the larger carboxyl quantity and stronger electronegativity manifested via FTIR spectra and zeta potential analysis. Through the adsorption experiments, the optimal pH value of 8 and the suitable absorbent dosage of 0.03 g were obtained. The simulation results showed that the Freundlich model can fit the adsorption thermodynamic data quite well, while the kinetic data was simulated preferably by the pseudo-second-order kinetic equation signifying the chemical adsorption process, and the intra-particle diffusion was involved in the adsorption consisted of three stages. The findings of batch experiments under diverse operations represented that MBARs purified aqueous CIP better than UBARs, closely related to the superior electronegativity. Both characterization and adsorption studies illustrated the dominant role of electrostatic interaction during CIP removal, accompanied by hydrogen bonding and diffusion interaction besides. The present work suggested that MBAR fibers could possess a promising application to ciprofloxacin potent removal from aqueous solutions.

Characterization of raw and alkali treated new natural cellulosic fibres extracted from the aerial roots of banyan tree.

The objective of this investigation is to check the suitability novel cellulosic fibre extracted from the aerial roots of Banyan tree (ARBFs) as reinforcement in fibre reinforced plastics. The Fundamental properties of ARBFs such as density, tensile strength, chemical composition, crystallinity index, crystalline size, thermal stability, maximum degradation temperature and surface roughness were studied. The chemical analysis results revealed that after the alkalization cellulose content was improved while hemi-cellulose, lignin and wax content were demised. The enhancement in the crystallinity index (76.35% from 72.47%) and crystalline size (7.74 nm from 6.28 nm) of alkali treated ARBFs were evidenced by the X-ray diffraction analysis. Thermal analysis results confirmed that maximum degradation temperature (368 °C) and kinetic activation energy (75.45 kJ/mol) of alkali treated ARBFs had increased from 358 °C and 72.65 kJ/mol respectively. The results of scanning electron microscopic and atomic force microscopic analysis exhibited that impurities and wax on the outer surface of the ARBFs were removed after the alkali treatment. All the above finding concluded that ARBFs is the appropriate material to use as a reinforcement in fibre reinforced plastics.

Identification of Aerial Roots of Ficus microcarpa Linn. F. and Ficus elastica Roxb. Ex Hornem / 广州中医药大学学报

Objective To compare the pharmacognosy characteristics of aerial roots of Ficus microcarpa Linn.f. and Ficus elastica Roxb. ex Hornem.. Methods Fresh aerial roots were harvested and were used as the experimental samples. Stereoscopy was used for the observation of macroscopic appearance of Ficus microcarpa Linn.f. and Ficus elastica Roxb. ex Hornem.,and the microscope was used for the examination of their microscopic features of the velamen surface, cross section of root tip, cross section and longitudinal section of the posterior root, and powder. Results The appearance characteristics of the two species were as follows:the number of aerial roots of Ficus microcarpa Linn. f. was more,and the diameter was smaller than that of Ficus elastica Roxb. ex Hornem. The root tips of Ficus microcarpa Linn. f. aerial roots were light yellow turning to yellow-white, covered with gray or yellowish-white lenticels;the root tips of Ficus elastica Roxb. ex Hornem. aerial roots were light yellow or yellow, covered with gray lenticels. Microscopic identification results of the two plants were as follows:the primary xylems of transverse section of root tips and posterior roots of Ficus microcarpa Linn.f. and Ficus elastica Roxb. ex Hornem. were different,the former being five to seven heptarch,and the latter being six to eleven heptarch. Both of the two species had non-articulated unbranched laticifers in their longitudinal section of posterior root, and the diameter of Ficus. elastica Roxb. ex Hornem. was slightly larger than that of Ficus microcarpa Linn. f.. The powder of Ficus microcarpa Linn. f. was red brown,with spiral and pitted vessels;Ficus elastica Roxb. ex Hornem. was yellow brown,with single small and large pitted vessels,and the color of its fiber was shallow or nearly colorless or even transparent, with lines of cluster crystal. Conclusion The results will provide evidence for the identification , exploitation and utilization of Ficus microcarpa Linn . f . and Ficus elastica Roxb. ex Hornem.

The quality evaluation of aerial roots of ficus microcarpa L.f. based on their anti-inflammation activity / 中国药学杂志

OBJECTIVE: To establish the quality evaluation method of the aerial roots of Ficus microcarpa L.f. based on their anti-inflammation activity. METHODS: Twenty batches of samples from different producing areas were analyzed by HPLC on a Shimadzu Capcell Pak C18 column(4.6 mm×250 mm,5 μm) gradiently eluted with mobile phase of methanol and 0.1% formic acid aqueous at a flow rate of 1.0 mL·min-1. The detection wavelength was set at 254 nm, and the column temperature was maintained at 35℃. The chromatograms were analyzed by the software "Similarity Evaluation System for Chromatographic Fingerprint of TCMs (Version 2012.1)" and the common peaks were obtained. The anti-inflammatory effects of the aerial roots of Ficus microcarpa L.f. were assessed by murine model of xylene-induced ear edema. Spectrum-effect relationship was analyzed by bivariate correlation analysis using SPSS21.0. RESULTS: Seventeen common peaks were identified in the HPLC fingerprints of 20 batches of aerial roots of Ficus microcarpa L.f. The anti-inflammatory effect of samples from Guangdong was better than those from Guangxi and Fujian (P<0.01). According to the result of spectrum-effect relationship analysis, six common peaks were closely related to the anti-inflammatory effects of the aerial roots of Ficus microcarpa L.f. (P<0.05). Cluster analysis was then carried out based on the six common peaks in order to divide the samples into different groups. CONCLUSION: The quality evaluation method established in this research is successfully employed in the quality evaluation of the aerial root of Ficus microcarpa L.f..

Comparative Identification of Aerial Roots of Ficus microcarpa Linn. f. and Ficus altissima Bl / 广州中医药大学学报

Objective To find out evidence for the identification of the aerial roots of Ficus microcarpa Linn. f. and F. altissima Bl.. Methods The fresh aerial roots of the two kinds of plants were collected. The appearance traits were observed by stereoscopy. The velamen surface, cross section of root tip, cross section of the posterior root and powder of two kinds of aerial roots were observed under microscope. Results The number of aerial roots of F. microcarpa Linn. f. was more than that of F. altissima Bl., while the diameter was less than that of F. altissima Bl.. Differences were shown in primary xylems of the transverse section of root tip and posterior root of the two kinds of aerial roots, there were 5-7 vascular bundles in F. microcarpa Linn. f. and 7-10 vascular bundles in F. altissima Bl.. As for the powder, the powder of F. microcarpa Linn. f. was yellowish brown, while that of F. altissima Bl. was reddish brown; F. altissima Bl. had more fibers and longer diameter than F. microcarpa Linn. f. and had cluster crystals in order. Conclusion The appearance and microstructure features showed by the results can be used to distinguish the aerial roots of F. microcarpa Linn. f. and F. altissima Bl..

Size-correlated morpho-physiology of the aroid vine Rhodospatha oblongata along a vertical gradient in a Brazilian rain forest.

In this work, we analyse morpho-physiological modifications presented during the allomorphic growth of the aroid vine Rhodospatha oblongata Poepp throughout its ascent into the forest canopy. We test the hypothesis that morphological modifications in the root, shoot and leaf are followed by a gradual improvement of the xylem vascular system in order to increase water acquisition and transport as body size increases. The characterisation of these structural modifications was based on 30-35 specimens divided into six size classes. The dimensions of shoots, leaves and roots were quantified and qualified. The transition from the terrestrial to the epiphytic phase was followed by a simultaneous increase of leaf number and lamina area, together with increased length and diameter of the petiole. Furthermore, as the plant grows, the shoot internodes become shorter and thicker. However, occurrence of aerial roots is the most important characteristic in the ascending phase. In taller individuals, the increase in number of roots with wider xylem vessels guarantees an increased theoretical xylem hydraulic conductance for this growth phase. Along an acropetal direction of the same shoot, the diameter of xylem vessels increased, while the number of vessels per stele area decreased, in contrast with such allometric models as that of West, Brown and Enquist, showing that xylem vessel number and diameter taper in a reverse manner along the same direction. Such structural changes of R. oblongata allow improved foraging for light and water, facilitating the survival of bigger-sized plants of this vine in the canopy.