Stem Nodes Research Articles

Comparation of Se accumulation and distribution of two rice (Oryza sativa L.) cultivars with high- and low- Se efficiency as affected by exogenous application of selenite

BackgroundIn production, increasing Selenium (Se) level of rice grain could be achieved by adding exogenous Se and selecting Se efficient rice cultivars. However, the accumulation and distribution of Se in rice cultivars with high- and low-efficiency after Se application is not well documented. A pot experiment with two Se levels was carried out on two rice cultivars. ResultsSe concentration in grain, shoot and root of Se efficient rice was significantly higher than that of Se inefficient rice with Se application (p < 0.05). Besides, Se application significantly increased the expression of NRT1.1B gene in stem nodes of Se efficient rice in comparison to Se inefficient rice. The proportion of Se accumulation in shoot and spike of Se efficient rice was 18.3% and 9.5% higher than that in Se inefficient rice when Se was applied. Moreover, the contents of various mineral elements in leaf showed that Se enhanced the concentration of most elements in Se efficient rice, indicating that it seems to be a better cooperative transport relationship between Se and other mineral elements in Se efficient rice. The spatial distribution of Se, Fe, Mn, Cu and Zn in Se efficient rice grains was tended to be distributed distal to the embryo, while such elements in Se inefficient rice grains was more concentrated proximal to the embryo, which indicated that Se efficient rice could make better use of the storage capacity of grain. ConclusionsHigher Se accumulation in Se efficient rice primarily attributed to the increase of Se transport capability and Se source as well as better synergistic effects between Se and other mineral elements. The findings will provide theoretical support for breeding new rice varieties and developing Se-enriched rice industry.

Effect of Plant Growth Regulators on in vitro Morphogenic Response of Gliricidia [Gliricidia sepium (Jacq.) Steud.

Background: The present investigation was carried out with the objective of optimization of rapid micropropagation protocol and to evaluate effect of different concentrations of plant growth regulators added singly or in combinations on in vitro culture of Gliricidia sepium. Methods: Explants (Soft nodal stem segments) were inoculated on MS medium containing varying concentrations of cytokinins and auxins either singly or in combinations. The cultures were incubated at 25±2°C for 14: 10 hour’s photoperiod with a light intensity of 3000-3500 lux. Result: Maximum number of shoot bud induction obtained when MS medium was supplemented with 0.5 mg/l BAP with 100 per cent frequency. Highest frequency (100%) of rooting was observed at 0.5 mg/l of IAA. 2.0 mg/l NAA showed highest number of roots/explant but the roots were thick. For shoot bud induction, BAP was found to be most effective among all the plant growth regulators. For root induction, both NAA and IAA were found to be effective but IAA exhibited higher frequency of rooting as compared to NAA.

Photoperiod Affects Node Appearance Rate and Flowering in Early Maturing Soybean

The photoperiod plays a critical role in the control of flowering timing in soybean (Glycine max (L.) Merr.) with long days increasing the time to flowering. Early flowering cultivars have been developed from breeding programs for environments with long photoperiods; however, this effect is challenging to isolate in field experiments because of other environmental influences. Our experiment examined the effect of photoperiod on the node appearance rate and time to flower for 13 early maturing soybean cultivars ranging in maturity group (MG) between 000.9 and 1.3. Growth chambers were programmed to 14, 15, 16, and 17 h photoperiods and temperature was kept at 25 °C. The date of emergence and main stem node appearance were recorded until flowering. The node appearance rate was slowest for the first node and increased thereafter. All cultivars required more time to flowering in the longer photoperiod treatments and the later rated MG had the greatest sensitivity to photoperiod. A delay in time to flower from a longer photoperiod can delay maturity and expose the crop to fall frost that can reduce seed yield and quality. Understanding and documentation of soybean photoperiod sensitivity will help plant breeders develop suitable cultivars for environments with long photoperiods.

Spatial Location of Sugarcane Node for Binocular Vision-Based Harvesting Robots Based on Improved YOLOv4

Spatial location of sugarcane nodes using robots in agricultural conditions is a challenge in modern precision agriculture owing to the complex form of the sugarcane node when wrapped with leaves and the high computational demand. To solve these problems, a new binocular location method based on the improved YOLOv4 was proposed in this paper. First, the YOLOv4 deep learning algorithm was improved by the Channel Pruning Technology in network slimming, so as to ensure the high recognition accuracy of the deep learning algorithm and to facilitate transplantation to embedded chips. Secondly, the SIFT feature points were optimised by the RANSAC algorithm and epipolar constraint, which greatly reduced the mismatching problem caused by the similarity between stem nodes and sugarcane leaves. Finally, by using the optimised matching point to solve the homography transformation matrix, the space location of the sugarcane nodes was for the first time applied to the embedded chip in the complex field environment. The experimental results showed that the improved YOLOv4 algorithm reduced the model size, parameters and FLOPs by about 89.1%, while the average precision (AP) of stem node identification only dropped by 0.1% (from 94.5% to 94.4%). Compared with other deep learning algorithms, the improved YOLOv4 algorithm also has great advantages. Specifically, the improved algorithm was 1.3% and 0.3% higher than SSD and YOLOv3 in average precision (AP). In terms of parameters, FLOPs and model size, the improved YOLOv4 algorithm was only about 1/3 of SSD and 1/10 of YOLOv3. At the same time, the average locational error of the stem node in the Z direction was only 1.88 mm, which totally meets the demand of sugarcane harvesting robots in the next stage.

Distinct metabolic profiling is correlated with bisexual flowers formation resulting from exogenous ethephon induction in melon (Cucumis melo L.).

Melon (Cucumis melo L.) is an agronomically important vegetable. Most cultivars of melon are andromonoecious and bisexual flowers only emerged from the leaf axil of lateral branches. However, the regulatory mechanism contributing to the occurrence of bisexual flowers were still obscure. In this study, ethephon was applied in two common cultivars of melon. In control without ethephon treatment, no bisexual flower was made in the main stem. However, 6.56 ± 1.42 and 6.63 ± 0.55 bisexual flowers were respectively induced in main stem of ‘Yangjiaocui-QX’ and ‘Lvbao’ after ethephon treatment, and induced bisexual flowers distributed in 12–20 nodes of main stem. During the formation of bisexual flowers, 41 metabolites were significantly up-regulated and 98 metabolites were significantly down-regulated. According to the KEGG enrichment analysis of 139 different metabolites, a total of 30 pathways were mapped and KEGG terms of “Phenylalanine, tyrosine and tryptophan biosynthesis”, “Phenylalanine metabolism” and “Flavone and flavonol biosynthesis” were significantly enriched. In three significantly enriched KEGG terms, shikimic acid, L-tryptophan, L-phenylalanine, and kaempferol were significantly up-regulated while L-tyrosine, 4-hydroxycinnami acid and luteolin were significantly down-regulated in ET compared to CK. Different metabolites were also classified depend on major class features and 14 classes were acquired. The results of metabonomics and endogenous hormone identification indicated that ethylene could enhance the concentration of salicylic acid, methyl jasmonate, ABA and IAA. This study provided an important theoretical foundation for inducing bisexual flowers in main stem and breeding new varieties of melon in future.

A functionally divergent SOC1 homolog improves soybean yield and latitudinal adaptation

Soybean (Glycine max) grows in a wide range of latitudes, but it is extremely sensitive to photoperiod, which reduces its yield and ability to adapt to different environments. Therefore, understanding of the genetic basis of soybean adaptation is of great significance for breeding and improvement. Here, we characterized Tof18 (SOC1a) that conditions early flowering and growth habit under both short-day and long-day conditions. Molecular analysis confirmed that the two SOC1 homologs present in soybeans (SOC1a and SOC1b) underwent evolutionary functional divergence, with SOC1a having stronger effects on flowering time and stem node number than SOC1b due to transcriptional differences. soc1a soc1b double mutants showed stronger functional effects than either of the single mutants, perhaps due to the formation of SOC1a and SOC1b homodimers or heterodimers. Additionally, Tof18/SOC1a improves the latitudinal adaptation of cultivated soybeans, highlighting the functional importance of SOC1a. The Tof18G allele facilitates adaptation to high latitudes, whereas Tof18A facilitates adaptation to low latitudes. We demonstrated that SOC1s contribute to floral induction in both leaves and shoot apex through inter-regulation with FTs. The SOC1a-SOC1b-Dt2 complex plays essential roles in stem growth habit by directly binding to the regulatory sequence of Dt1, making the genes encoding these proteins potential targets for genome editing to improve soybean yield via molecular breeding. Since the natural Tof18A allele increases node number, introgressing this allele into modern cultivars could improve yields, which would help optimize land use for food production in the face of population growth and global warming.

Removal of Copper (II) from Aqueous Solution by a Hierarchical Porous Hydroxylapatite-Biochar Composite Prepared with Sugarcane Top Internode Biotemplate

Porous hydroxyapatite-biochar composites with layered microstructures (SC–HA/C) were prepared by carbonizing sugarcane stem nodes and then soaking them in lime water and (NH4)2HPO4 solutions in rotation. The surface area of SC–HA/C ranges from 8.52 to 28.44 m2/g, and its microstructure inherits various macro-, meso-, and micro-pores in the cell walls of sugarcane and in the pits of the vessel walls. The maximum removal capacities were 11.50, 14.65, and 19.81 mg/g for the Cu (II) immobilization at 25 °C, 35 °C, and 45 °C with the solution Cu (II) concentration of 10~320 mg/L, respectively, which were in accordance with the copper sorption capacities of synthesized nano-hydroxylapatites. The Cu (II)-removal kinetics and isotherm followed the pseudo-second-order equation and the Langmuir equation very well. The formation of the Cu-containing hydroxylapatite solid solutions ((CuxCa1−x)5(PO4)3(OH)) through adsorption, ion exchange (x = 0.01~0.04), and dissolution-coprecipitation (x = 0.13~0.35) was the dominant process for the Cu (II) removal by the SC–HA/C composite.

Effect of NAA and Chitosan in rooting branches resulting from stem nodes plantation of Kumquat (Citrus japonica) in vitro

The research was conducted in a Plant Tissue Culture Laboratory, Agricultural Research Department, Ministry of Science and Technology, from December 10/1/2019 to December 30/1/2021, to study the effect of adding auxin NAA at concentrations (1, 2, and 3) mg L-1, and interaction with Chitosan at concentrations (10, 15, 20 and 25) mg L-1, to the culture media MS, to determine the optimal concentration in rooting the branches resulting from the multiplication of micro branches of the Kumquat plants (Citrus japonica), produced from in vivo development of the stem nodes. The results of the study showed that the planting of Kumquat branches in MS media supplemented with 2.0 mg L-1 NAA was a high significant response on rooting percentage (92.0%) and roots number (3.20 plant root-1), added 15 mg L-1 chitosan to the culture media prepared with 2.0 mg L-1 NAA was a significantly increased in same parameters (rooting percentage 80% and roots number 5.60).

Identification and Analysis of the EIN3/EIL Gene Family in Populus × xiaohei T. S. Hwang et Liang: Expression Profiling during Stress

The ethylene-insensitive 3-like (EIN3/EIL) gene family, as a transcriptional activator in plants, not only plays an important role in the ethylene-signaling pathway in regulating plant growth and development but also participates in the defense against various biotic and abiotic stresses. However, there are few studies on the functions of EIN3/EIL genes in woody plants. Populus × xiaohei is a kind of tree species with strong drought resistance and salt-alkali tolerance and, thus, is an ideal subject for studying abiotic stress mechanisms in trees. Eight EIN3/EIL genes were cloned from Populus × xiaohei. Bioinformatic analysis showed that the PsnEIN3/EIL gene contained a highly conserved EIN3 domain, N-terminal sites rich in proline and glutamine, and other EIN3/EIL family structural characteristics. The results of a multi-species phylogenetic analysis showed that the family EIN3/EIL proteins were divided into three groups (A, B, and C). EIL3 and EIL4 belonged to groups A and B, while EIL2 and EIN3 generally belonged to group C. Analysis of tissue expression characteristics showed that PsnEIN3/EIL was expressed in different tissues and was involved in the development of stem nodes and leaves. The response analysis of the expression of PsnEIN3/EIL under abscisic acid (ABA) and abiotic stresses (salts, heavy metals, alkaline conditions, and drought) showed changes in expression, suggesting that PsnEIN3/EIL may be involved in the processes of plant hormone responses to salts, heavy metals, alkaline conditions, and drought. This study provides a foundation for further elucidation of the functions of EIN3/EIL genes in forest growth and development and abiotic stress responses.

Transcriptional analyses of maize leaves in response to high‐density planting

AbstractMaize (Zea mays L.) is one of the major cereal crops worldwide. Increasing planting density is an effective way to improve crop yield. However, plants grown under high‐density conditions compete for water, nutrients, and light, which often leads to changes in productivity. To date, few studies have determined the transcriptomic differences in maize leaves in response to different planting densities. This study examined the whole‐genome expression patterns in the leaves of maize planted under high and low densities to identify density‐regulated genes. Leaves at upper, ear, and lower stem nodes were collected at the grain‐filling stage of the maize hybrid Xianyu335 grown under low‐density planting and high‐density planting. In total, 72, 733, and 1,739 differentially expressed genes (DEGs) were identified in the respective upper, ear, and lower leaves under HDP. Upregulated and downregulated DEGs in the upper and lower leaves were similar in number, whereas upregulated DEGs in the ear leaves were significantly higher in number than the downregulated DEGs. Functional analysis indicated that genes responding to HDP‐related stresses were mediated by pathways involving four phytohormones responsible for metabolism and signaling, osmoprotectant biosynthesis, transcription factors, and fatty acid biosynthesis and protein kinases, which suggested that these pathways are affected by the adaptive responses of maize plants grown at high density. Research findings elucidated the molecular mechanisms underlying the physiological and biochemical responses of the leaves of maize planted at high density.

Salicylic Acid Enhances Adventitious Root and Aerenchyma Formation in Wheat under Waterlogged Conditions.

The present study investigated the role of salicylic acid (SA) in regulating morpho-anatomical adaptive responses of a wheat plant to waterlogging. Our pharmacological study showed that treatment of waterlogged wheat plants with exogenous SA promotes the formation axile roots and surface adventitious roots that originate from basal stem nodes, but inhibits their elongation, leading to the formation of a shallow root system. The treatment also enhanced axile root formation in non-waterlogged plants but with only slight reductions in their length and branch root formation. Exogenous SA enhanced the formation of root aerenchyma, a key anatomical adaptive response of plants to waterlogging. Consistent with these results, waterlogging enhanced SA content in the root via expression of specific isochorismate synthase (ICS; ICS1 and ICS2) and phenylalanine ammonia lyase (PAL; PAL4, PAL5 and PAL6) genes and in the stem nodes via expression of specific PAL (PAL5 and PAL6) genes. Although not to the same level observed in waterlogged plants, exogenous SA also induced aerenchyma formation in non-waterlogged plants. The findings of this study furthermore indicated that inhibition of ethylene synthesis in SA treated non-waterlogged and waterlogged plants does not have any effect on SA-induced emergence of axile and/or surface adventitious roots but represses SA-mediated induction of aerenchyma formation. These results highlight that the role of SA in promoting the development of axile and surface adventitious roots in waterlogged wheat plants is ethylene independent while the induction of aerenchyma formation by SA requires the presence of ethylene.

In Vitro Propagation of Manihot Esculenta Crantz ‘Pirun 2’

Abstract In Thailand, cassava (Manihot esculenta Crantz ‘Pirun 2’) is an important economic crop. The tissue culture technique is used to produce true-to-type cassava plantlets on a large scale within a short period. Therefore, the objective of this study was to investigate the optimum culture medium for cassava axillary bud in vitro propagation. Stem nodes were treated with a solution of 20% (v/v) commercial bleach (25% w/v NaOCl) for 10 minutes. Then, the sterilized buds were cultured on three different types of culture media: Murashige and Skoog (MS), Driver and Kuniyaki Walnut (DKW), and MS supplemented with NAA and BA. Various parameters were evaluated for their effects on plantlet development (height of shoot and numbers of leaves, roots, and shoots after 1 month). The results showed that the mean (± standard deviation) numbers of leaves (6.67 ± 0.82) and roots (2.50 ± 0.55) were significantly higher when they were cultured on MS medium. In addition, the highest number of shoots (3.67±0.82) was obtained on MS medium supplemented with 0.05 mg/l NAA+1 mg/l BA. The cut shoots of plantlets cultured on MS medium without hormones developed into mature plantlets after 1 month. Thus, the MS medium was the optimum for mature cassava Pirun 2 culture. This protocol would be useful for plantlet induction on MS medium supplemented with NAA and BA hormones to produce more shoots and for transfer to MS medium without rooting hormones. Moreover, in vitro derived plantlets were successfully acclimatized on a peat moss which gave the high percentage of transplanting survival (100%). Keywords: Axillary bud, Cassava, Stem node, Surface sterilization, Tissue culture

Terminal Velocity Determinations for Switchgrass Nodes and Internodes

HighlightsA vertical wind tunnel was fabricated to aerodynamically suspend switchgrass particles to measure terminal velocity.Overall terminal velocity estimates for node and internode were 8.04 and 5.68 m s-1, respectively.Terminal velocity prediction equation for spherical particles (Mohsenin, 1970) produced values almost identical to experimental values unlike an equation for infinite-length cylindrical particles.Hollow switchgrass particle behavior was complex with particle bouncing, rolling, tumbling, and other dynamic behaviors during aerodynamic equilibrium. Abstract. Terminal velocity is a fundamental aerodynamic property often used to separate plant anatomical components. A vertical wind tunnel was fabricated to investigate whether terminal velocities of switchgrass stem internodes and nodes were distinctly different. Wind tunnel features included a clear observation section for suspended particles and fine adjustment of airflow. Each sample terminal velocity was measured with 45 anemometer readings from nine locations and five repeated measures. The experiment evaluated two sample moisture contents (52% and 15% wet basis, hereafter referred to as w.b.), three particle lengths (0.64, 1.27, and 2.54 cm), node versus internode, and 12 replications. The 6,480 anemometer readings provided significant differences between factors and interactions. The greatest magnitude in mean terminal velocity difference was 4.55 m s-1 (i.e. 9.62 to 5.07) that resulted in a velocity ratio of 190% [(9.62/5.07) x 100]. The least magnitude of mean terminal velocity difference, while significant, was 0.36 m s-1 (i.e. 6.59 to 6.23). This offered a limited difference and may indicate that separations may need to be confined within groups of moisture category and/or particle length. Terminal velocity measurements were most similar to those calculated using the Mohsenin (1970) spherical particle equation yielding a mean (6.86 vs. 6.91 m s-1), standard deviation (1.41 vs. 1.42 m s-1), minimum (4.65 vs. 4.69 m s-1), and maximum (9.95 vs. 10.03 m s-1) for measurement and spherical particle equation, respectively. Keywords: Anatomical component, Biomass property, Physical experiment, Separation, Sorting, Switchgrass, Vertical wind tunnel.

Describing biodiversity in the genomics era: A new species of Nearctic Cynipidae gall wasp and its genome

ABSTRACTGall wasps (Hymenoptera: Cynipidae) specializing on live oaks in the genus Quercus (subsection Virentes) are a relatively diverse and well‐studied community with 14 species described to date, albeit with incomplete information on their biology, life history and genetic structure. Incorporating an integrative taxonomic approach, we combine morphology, phenology, behaviour, genetics and genomics to describe a new species, Neuroterus valhalla sp. nov. The alternating generations of this species induce galls on the catkins and stem nodes of Quercus virginiana and Quercus geminata in the southern United States. We describe both generations in the species' life cycle, and primarily use samples from a population in the centre of Houston, Texas, thus serving as an example of the undescribed biodiversity still present in well‐travelled urban centres. In parallel, we present a draft assembly of the N. valhalla genome providing a direct link between the type specimen and reference genome. The genome of N. valhalla is the smallest reported to date within the tribe Cynipini, providing an important comparative contrast to the otherwise large genome size of cynipids. While relatively small, the genome was found to be composed of &gt;64% repetitive elements, including 43% unclassified repeats and 11% retrotransposons. A preliminary ab initio and homology‐based annotation revealed 32,005 genes, and a subsequent orthogroup analysis grouped 18,044 of these to 8186 orthogroups, with some evidence for high levels of gene duplications within Cynipidae. A mitochondrial barcode phylogeny linked each generation of the new species and a phylogenomic ultraconserved element (UCEs) phylogeny indicates that the new species groups with other Nearctic Neuroterus. However, both phylogenies present the genus Neuroterus in North America as polyphyletic.

Growth of Bush Pepper Seedlings of Different Sources of Cuttings Grown on Various Growing Media Formulas

Pepper grows creepingly following the growth of its climbing plants, making it difficult to maintain and harvest. Therefore, bush pepper cultivation was developed by replacing climbing trees with 1.5 m high concrete. However, seedlings that can grow into bush pepper are cuttings from fruit branches and primary branches, which are difficult to grow because the nodes of these branches do not have root primordia. This study aimed to obtain cuttings that can grow into bush pepper on the most superior growing media. The experiment was arranged using a completely randomized design (CRD) with two treatment factors, namely formulas of growth media (M1= soil + organic fertilizer + husk; M2= soil + organic fertilizer + compost; M3= soil + organic fertilizer + husk ash; and M4= soil + organic fertilizer + moss) and sources of cuttings (S1= climbing stem; S2= axillary branch; S3= fruit branch; and S4= primary branch with one main stem node). Based on the growth percentage of fruit branches and primary branches in the seedlings, cuttings from climbing stem and axillary branches were not able to grow into bush pepper, because fruit and primary branches only grew less than 5% in all media formulas. Cuttings from fruit branches and primary branches affect the formation of bush pepper with an average percentage of growth of fruit branches and primary branches of more than 95% on M2 and M3 media. Growth of buds, leaves and roots of cuttings from climbing stem and axillary branch was significantly better than cuttings from fruit branches and primary branches.

Astragalus nurhakdagensis (sect. Hololeuce Bunge / Fabaceae), a new species from Turkey

Astragalus nurhakdagensis, a new species from the south of Turkey was described, illustrated, and compared to the closest taxa Astragalus hirsutus, A. dumanii and A. cataonicus from which it is set apart by a longer calyx length (13-14 mm) and calyx teeth (7-9 mm, longer than tube), white corolla colour, longer bracts (13-15 mm) and black hairy stripes below the stem nodes. In A. hirsutus, the calyx length (6-10 mm) and calyx teeth are much smaller (2-3 mm long, shorter than tube), with yellow corolla colour and without black hairy stripes. It also differs from A. dumanii with its longer stipules 9-13 mm (not 5-8 mm), bracts 13-15 mm (not 4-6 mm), calyx length 13-14 mm (not 7-10 mm) and calyx teeth 7-9 mm (not 2-4 mm), and also with spreading hairs (not adpressed) on the calyx and 7-9 pairs of leaflets (not 3-7 pairs). It is also differentiated from A. cataonicus with a white corolla colour (not lilac to pink), longer stipule 9-13 mm (not 5-7 mm), bracts 13-15 mm (not 6-12 mm), and longer calyx teeth 7-9 mm (not 5-7 mm). Prolate (A. nurhakdagensis, A. hirsutus and A. cataonicus) and subprolate (A. dumanii) shapes were determined in the tricolporate pollen grains. Perforate, granulate, and reticulate ornamentation types were observed in the pollen grains in SEM. The seed shapes were reniform? globose in A. nurhakdagensis and A. dumanii, whereas they were reniform in A. hirsutus and A. cataonicus. Surface ornamentation of the seeds differed slightly: rugulate in A. nurhakdagensis and A. hirsutus, reticulate-rugulate in A. dumanii and reticulate-striate in A. cataonicus. Taxonomic description, micrographs of seeds and pollen surfaces and geographical distribution of the new species were provided. Conservation status was discussed.

Study on in vitro propagation of Sophora tonkinensis Gagnep through stem node culture

In the present study, authors propagated Sophora tonkinensisGagnep plants using stem nodal culture. The results indicated that on MS medium supplemented with 30 g/l sucrose, 5.5 g/l agar, 200 ml/l coconut water, 1 g/l activated charcoal, 0.75 mg/l TDZ shoots proliferated from stem segments have the best count and height of shoots. The most appropriate medium for multiplication of shoots was the MS medium supplemented with 30 g/l sucrose, 5.5 g/l agar, 200 ml/l coconut water, 1 g/l activated charcoal, 0.75 mg/l TDZ, 0.5 mg/l IBA, 2.0 g/l peptone, 30 g/l carrot puree, pH 5.5 with the results of 20.60 shoots/explant, shoot height of 3.75 cm and 4.6 leaves/shoot after 8 weeks of culture. Root formation of shoots carried out on the MS medium supplemented with 30 g/l sucrose, 5.5 g/l agar, 200 ml/l coconut water, 1 g/l activated charcoal, 1.0 mg/l αNAA gave the best result. In the nursery, a mixture of humus + coconut fiber powder (70:30 ratio) was regarded as the best substrate due to the high survival rate of plantlets (92%) and healthy plantlets (10.30 cm high with 7.2 leaves and 4.3 new roots/a plantlet) at 10 weeks after planting

Breaking seed dormancy and regeneration in Cannabis sativa L.

Cannabis sativa L. is an important medicinal plant species that grow under natural conditions and has been legalized in 20 out of 81 Turkish provinces. The female inflorescence is a highly branched compound raceme with indeterminate habit of growth. This results in different maturing of seeds on the inflorescence and induce physiological dormancy on seeds. The study aimed to improve seed germination percentage using various concentrations of GA₃, GA₃ + BAP, germination on water and water solidified with agar, MS or Gamborg B5 medium. The results showed that the best seed germination was noted on Gamborg B5 medium. Different explants were used to regenerated plantlets on Gamborg B5 medium. All explants were suitable for callus regeneration variably. Only the stem nodes of Samsun Vezirköprü were suitable to induce shoots and plantlets. These plantlets were acclimatized on clay loam soils and transferred to field condition during October 2020, where they acclimatized successfully. These studies provide an effective insight into the mechanism seed dormancy in C. sativa. Further studies using other plant growth regulator concentrations will improve shoot regeneration and aid in utilizing the methods for breeding purpose.

First Report of Maize Stalk Rot Caused by Fusarium nelsonii in China.

Maize (Zea Mays L.) is one of the main crops in Ningxia Province, China, and stalk rot has become a serious disease of maize in this area. Infected plants showed softening of the stalks at lower internodes, which lodged easily and died prematurely during grain filling, and the pith tissue internally appeared to be disintegrating and slightly brown to reddish. In September 2018, symptomatic tissue was collected from seventeen locations in Ningxia. The incidence ranged from 5% to 40% in surveyed fields, reaching as high as 86% in certain plots. The discolored stalk pith tissues from the lesion region were cut into small pieces (approximately 0.5 × 0.2 cm), superficially disinfected with 75% ethanol for 1 min and rinsed three times with sterile water before plating on potato dextrose agar (PDA) medium with chloromycetin. The purified strains were obtained by single-spore separation and transferred to PDA and carnation leaf agar (CLA) medium. Morphological and molecular characteristics confirmed the presence of nine Fusarium species in these samples, including Fusarium graminearum species complex and Fusarium verticillioides. Four isolates of Fusarium nelsonii were recovered from samples collected in Shizuishan and Wuzhong. On PDA plates, the floccose to powdery, white to rose-colored aerial mycelia were produced and covered plates after 8 days of incubation, producing abundant mesoconidia and chlamydospores. Mesoconidia were fusiform or lanceolate until slightly curved with 0-3 septa, and chlamydospores were initially smooth and transparent, and became verrucous and light brown. Macroconidia produced in CLA were straight or curved and falcate, usually having 3-5 septa, with beak-shaped strongly curved apical cells and foot-shaped basal cells. Two isolates (SS-1-7 and ZY-2-2) were selected for molecular identification, and the total DNA was extracted using a fungal genomic DNA separation kit (Sangon Biotechnology, Shanghai, China). Sequence comparison of EF-1α (GenBank accession numbers MW294197 and MW294198) and RPB2 (Accession MW294176 and MW294177) genes showed 97% homology with the sequences of F. nelsonii reported in GenBank (accession MN120760 for TEF and accession MN120740 for RPB2). Pathogenicity tests with two isolates (SS-1-7 and ZY-2-2) were performed by individually inoculating five 10-leaf stage maize plants at between the 2nd and 3rd stem nodes from the soil level with 20 μl conidial suspension at a concentration of 106 conidia/ml as described by Zhang et al. (2016). Five maize plants inoculated with sterile water were used as controls. The inoculated plants were kept at 25 ± 0.5°C in the greenhouse with a photoperiod of 12 h. After 30 days, all plants inoculated with the conidial suspension formed an internal dark brown necrotic area around the inoculation site, whereas the control plants showed no symptoms. The pathogen was re-isolated from the necrotic tissue of the inoculated plants and identified by morphological characteristics as F. nelsonii. This species was first described by Marasas et al. (1998), and it is expanding its host range and has been isolated from sorghum, Medicago, wheat, and cucumber (Ahmad et al. 2020). The pathogen should be paid more attention owing to a serious risk of trichothecene and aflatoxin contamination (Astoreca et al. 2019; Lincy et al. 2011). To our knowledge, this is the first report of maize stalk rot caused by F. nelsonii in China.

"Breeding on Mountains" Resulted in the Reorganization of Endophytic Fungi in Asexually Propagated Plants (Ligusticum chuanxiong Hort.).

“Breeding on mountains, cultivation in dam areas” is a unique propagation method for the vegetatively propagated plant Ligusticum chuanxiong, including two transplants between the mountain and the dam area. It is well known that the environment can influence the endophytic community structure of plants. However, the change of host endophytic flora caused by transplanting in different places and its influence on asexual reproduction are still poorly understood. We carried out three cycles of cultivation experiments on L. chuanxiong and collected stem nodes (LZ), immature rhizomes (PX), medicinal rhizomes (CX), and rhizosphere. High-throughput sequencing was performed to analyze the endophytic fungi in all samples. We observed that the diversity and richness of endophytic fungi in L. chuanxiong increased as a result of transplanting cultivation from dam areas to mountains. Local transplantation caused minor changes in the endophytic fungus structure of L. chuanxiong, while remote transplantation caused significant changes. Compared with LZ after breeding in the dam area, the LZ after breeding on mountains has more abundant Gibberella, Phoma, Pericona, Paraphoma, and Neocosmospora. The regular pattern of the relative abundance of endophytic fungi is consistent with that of the fungus in the soil, while there are also some cases that the relative abundance of endophytic fungi is the opposite of that of soil fungi. In addition, there is a significant correlation among certain kinds of endophytic fungi whether in the soil or the plants. We have isolated more gibberellin-producing and auxin-producing fungi in the LZ cultivated in the mountains than that in the LZ cultivated in the dam area. The results of pot experiments showed that the three fungi isolated from LZ cultivated in mountainous areas can promote the development of shoots, stem nodes, and internodes of LZ, and increase the activity of plant peroxidase, catalase, phenylalanine ammonia lyase, and other enzymes. We can conclude that transplantation leads to the recombination of the host endophytic fungus, the more significant the difference in the environment is, the greater the reorganization caused by transplanting. Reorganization is determined by the soil environment, hosts, and the interaction of microorganisms. Remote transplantation is a crucial opportunity to reshuffle the micro-ecological structure of the asexual reproduction of plants, and regulate the growth, development, and resistance of plants, and prevent germplasm degradation caused by asexual reproduction.