Vascular Bundle Tissue Research Articles

Infection Process of Alfalfa Root Rot Caused by Fusarium acuminatum

Fusarium spp. can cause root rot in alfalfa, leading to the death of the whole plant, which seriously affects the yield and quality of alfalfa. This study used a Fusarium acuminatum strain labeled with green fluorescent protein (GFP) to observe the infection process of F. acuminatum on alfalfa by confocal fluorescence microscopy. The aim of this study was to reveal the infection mechanism of alfalfa Fusarium root rot at the cellular histological level. The results showed that conidia of F. acuminatum attached to the surface of the root and germinated at one day post-inoculation, the mycelium then entered the vascular bundle tissue of the alfalfa root at 5 days post-inoculation, reached the base of the plant stem at 14 days post-inoculation, and colonized the stem of the first and second compound leaf at 28 and 49 days post-inoculation, respectively. Moreover, the experiment, which sprayed a spore suspension, showed that the conidia of F. acuminatum could spread through the air to infect the pericarp and seed coat tissue of the pod. For the first time, we report the infection process of alfalfa Fusarium root rot caused by F. acuminatum and clarify that F. acuminatum can initially infect the root tissue of alfalfa, colonize the bottom stem of the plant through systematic infection, and eventually cause the plant to wilt and die. The results reveal the infection mechanism of F. acuminatum at the cell level via histology and provide theoretical support for the development of control strategies and key control technologies for alfalfa root rot.

Efficient In Vitro Regeneration System and Comparative Transcriptome Analysis Offer Insight into the Early Development Characteristics of Explants from Cotyledon with Partial Petiole in Small-Fruited Pepper (Capsicum annuum).

In our research, we utilized six small-fruited pepper germplasms as materials, selected cotyledons with the petiole and hypocotyls as explants, and conducted in vitro regeneration studies. Our outcomes specify that the most suitable explant is cotyledon with the petiole, and the suitable genotype is HNUCA341. The optimal medium for inducing and elongating adventitious buds for this genotype is Murashige and Skoog medium (MS) + 9.12 μM Zeatin (ZT) + 0.57 μM 3-Indoleacetic acid (IAA), with a bud induction rate of 44.4%. The best rooting induction medium is MS + 1.14 μM IAA, with a rooting rate of 86.7%. Research on the addition of exogenous hormones has revealed that the induction speed of buds in small-fruited pepper (HNUCA341) in the combination of ZT and IAA hormones (abbreviated as ZI) is quicker, and the induction effect is better. The histological observations indicate that ZI treatment accelerates the initiation of explant division and differentiation, causing a shorter duration of vascular-bundle tissue production. The plant hormone signaling pathway was significantly enriched by Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, including ARR9 (LOC107843874, LOC107843885), ARR4 (LOC107848380, LOC107862455), AHK4 (LOC107870540), AHP1 (LOC107839518), LAX2 (LOC107846008), SAUR36 (LOC107852624), IAA8 (LOC107841020), IAA16 (LOC107839415), PYL4 (LOC107843441), and PYL6 (LOC107871127); these significantly enriched genes may be associated with in vitro regeneration. In addition, the carbon metabolism pathway and plant mitogen-activated protein kinase (MAPK) signaling pathway are also significantly enriched in KEGG. The results of the Gene Ontology (GO) analysis revealed that differentially expressed genes related to carbon metabolism and fixation, photosynthesis and MAPK signaling pathways were upregulated under ZI treatment. It was found that they might be associated with enhanced regeneration in vitro. Furthermore, we also screened out differentially expressed transcription factors, primarily from the MYB, bHLH, AP2/ERF, and NAC families. Overall, our work accumulated important data for the in-depth analysis of the molecular mechanism of in vitro regeneration of pepper, and provides valuable germplasm for establishing an efficient stable pepper genetic-transformation system based on tissue culture.

First Report of Sclerotinia sclerotiorum Causing Hibiscus rosa-sinensis Stem Rot in Guangxi, China.

Hibiscus rosa-sinensis, native to the south of China, is currently planted as an important landscaping tree species in more than 100 countries around the world. Since 2012, an unknown stem rot disease of H. rosa-sinensis has occurred sporadically in a few green belts of Nanning, Guangxi, China. In February 2023, the incidence rate of the disease in the southern part of the city (108°38'E, 22°77'N) reached 5-8%. The pathogen mainly infected the stems near the soil line and aboveground stems. Initially, brown spots appeared and developed into long strips of large spots around the stem, slightly sunken. Later, the diseased tissue cortex presented longitudinal cracks and the vascular bundle tissue was exposed like silk hemp. White mycelium appeared on the diseased stem surfaces under high humidity conditions, eventually maturing into hard black sclerotia (1.5 to 11.0 mm in length). The leaves turned yellow and the whole plant finally died. For fungal isolation, seven diseased plants distributed within 800 square meters were collected, and 35 symptomatic stem sections were surface disinfect with alcohol for 30s, 0.08% NaClO for 1 min, triple rinsed with sterile distilled water, and cultured in potato dextrose agar (PDA) medium at 28℃. Sclerotinia-like colonies were consistently isolated from all diseased tissues and four isolates (Z1-Z4) were purified (Bolton et al. 2006). Irregular white immature sclerotia were produced after 5 to 7 days on the edges of the plates and turned black after 7 to 14 days, with a size of 1.8 to 4.6 × 1.2 to 3.4 mm (avg. 3.3 × 2.4 mm, n = 20). For molecular characterization, three gene regions (ITS, CaM and Mcm7) were amplified (White et al. 1990; Carbone et al. 1999; Schmitt et al. 2009) and sequenced (GenBank accession nos.: ITS: OR016764 to OR016767; CaM: OR257811 to OR257814; Mcm7: OR345318 to OR345321). The sequences of three analyzed DNA fragments shared 100% identity with sequences of Sclerotinia sclerotiorum strains (accession nos. JN013184, AF341304, KF545468). To fullfill Koch's postulates, healthy H. rosa-sinensis nursery stocks at the six months stage were individually planted in plastic pots at 25±3℃. The base of the stem and upper three branches of each plant were wounded with a sterile needle and inoculated with 5-mm discs of mycelium grown on PDA, then the inoculation sites of stem bases were covered with one layer nursery substrate and those of branches were wrapped with transparent tape to maintain the humidity. Three plants were inoculated with each isolate. As a control, three plants were inoculated with PDA discs. All the inoculated plants with mycelial discs developed characteristic symptoms 5 to 8 days after inoculation. The inoculation sites appeared white mycelium and the leaves sagged and wilted. Later, black sclerotia appeared on the diseased stem and the whole plant withered, while the control plants remained symptomless. Fungal cultures reisolated from symptomatic plants were morphologically identical with the cultures used as inoculum. Sclerotinia sclerotiorum has only been reported from H. rosa-sinensis in Taiwan (Tai 1979). The pathogen is a widely distributed fungus, causing many economically important diseases on various plants (Hossain et al. 2023). To our knowledge, this is the first report of S. sclerotiorum causing H. rosa-sinensis stem rot in Chinese Mainland, laying the foundation for monitoring its occurrence and spread.

Analysis of seed production and seed shattering in a new artificial grassland forage: pigeon pea.

Pigeon pea is a perennial leguminous plant that is widely cultivated as a forage and pharmaceutical plant in subtropical and tropical areas, especially in artificial grasslands. Higher seed shattering is one of the most important factors in potentially increasing the seed yield of pigeon pea. Advance technology is necessary to increase the seed yield of pigeon pea. Through 2 consecutive years of field observations, we found that fertile tiller number was the key component of the seed yield of pigeon pea due to the direct effect of fertile tiller number per plant (0.364) on pigeon pea seed yield was the highest. Multiplex morphology, histology, and cytological and hydrolytic enzyme activity analysis showed that shatter-susceptible and shatter-resistant pigeon peas possessed an abscission layer at the same time (10 DAF); however, abscission layer cells dissolved earlier in shattering-susceptible pigeon pea (15 DAF), which led to the tearing of the abscission layer. The number of vascular bundle cells and vascular bundle area were the most significant negative factors (p< 0.01) affecting seed shattering. Cellulase and polygalacturonase were involved in the dehiscence process. In addition, we inferred that larger vascular bundle tissues and cells in the ventral suture of seed pods could effectively resist the dehiscence pressure of the abscission layer. This study provides foundation for further molecular studies to increase the seed yield of pigeon pea.

Green Synthesis of Iron Oxide (Hematite) Nanoparticles and Their Influence on Sorghum bicolor Growth under Drought Stress

Drought is a major abiotic stress that confronts plant growth and productivity, thus compromising food security. Plants use physiological and biochemical mechanisms to cope with drought stress, but at the expense of growth. Green-synthesized nanoparticles (NPs) have gained great attention in agriculture due to their environmental friendliness and affordability while serving as potential biofertilizers. This study investigates the role of hematite (αFe2O3) NPs, synthesized from Aspalathus linearis (rooibos), to improve Sorghum bicolor growth under drought stress. About 18 nm, spherical, and highly agglomerated hematite (αFe2O3) NPs were obtained. Sorghum seeds were primed with 5, 10, and 15 mg/L αFe2O3 NPs, and, after seven days of germination, the seedlings were transferred into potting soil, cultivated for fourteen days, and were subsequently water deprived (WD) for a further seven days. A reduction in plant height (78%), fresh (FW; 35%) and dry (DW; 36%) weights, and chlorophyll (chl) content ((total chl (81%), chla (135%), and chlb (1827%)) was observed in WD plants, and this correlated with low nutrients (Mg, Si, P, and K) and alteration in the anatomic structure (epidermis and vascular bundle tissues). Oxidative damage was observed as deep blue (O2●-) and brown (H2O2) spots on the leaves of WD plants, in addition to a 25% and 40% increase in oxidative stress markers (H2O2 and MDA) and osmolytes (proline and total soluble sugars), respectively. Seed priming with 10 mg/L αFe2O3 NPs improved plant height (70%), FW (56%), DW (34%), total Chl (104%), chla (160%) and chlb (1936%), anatomic structure, and nutrient distribution. Priming with 10 mg/L αFe2O3 NPs also protected sorghum plants from drought-induced oxidative damage by reducing ROS formation and osmolytes accumulation and prevented biomolecule degradation. The study concludes that green synthesized hematite NPs positively influenced sorghum growth and prevented oxidative damage of biomolecules by improving nutrient uptake and osmoregulation under drought stress.

Leaf trait covariation and controls on leaf mass per area (LMA) following cotton domestication.

The process of domestication has driven dramatic shifts in plant functional traits, including leaf mass per area (LMA). It remains unclear whether domestication has produced concerted shifts in the lower-level anatomical traits that underpin LMA and how these traits in turn affect photosynthesis. In this study we investigated controls of LMA and leaf gas exchange by leaf anatomical properties at the cellular, tissue and whole-leaf levels, comparing 26 wild and 31 domesticated genotypes of cotton (Gossypium). As expected, domesticated plants expressed lower LMA, higher photosynthesis and higher stomatal conductance, suggesting a shift towards the 'faster' end of the leaf economics spectrum. At whole-leaf level, variation in LMA was predominantly determined by leaf density (LD) both in wild and domesticated genotypes. At tissue level, higher leaf volume per area (Vleaf) in domesticated genotypes was driven by a simultaneous increase in the volume of epidermal, mesophyll and vascular bundle tissue and airspace, while lower LD resulted from a lower volume of palisade tissue and vascular bundles (which are of high density), paired with a greater volume of epidermis and airspace, which are of low density. The volume of spongy mesophyll exerted direct control on photosynthesis in domesticated genotypes but only indirect control in wild genotypes. At cellular level, a shift to larger but less numerous cells with thinner cell walls underpinned a lower proportion of cell wall mass, and thus a reduction in LD. Taken together, cotton domestication has triggered synergistic shifts in the underlying determinants of LMA but also photosynthesis, at cell, tissue and whole-leaf levels, resulting in a marked shift in plant ecological strategy.

Green-Synthesized Zinc Oxide Nanoparticles Mitigate Salt Stress in Sorghum bicolor

Salinity is an abiotic stress that is responsible for more than 50% of crop losses worldwide. Current strategies to overcome salinity in agriculture are limited to the use of genetically modified crops and chemicals including fertilizers, pesticides and herbicides; however these are costly and can be hazardous to human health and the environment. Green synthesis of nanoparticles (NPs) is an eco-friendly and cost-effective method, and they might serve as novel biostimulants. This study investigated for the first time the efficiency of ZnO NPs, synthesized from Agathosma betulina to mitigate salt stress in Sorghum bicolor. Hexagonal wurtzite ZnO NPs of about 27.5 nm, were obtained. Sorghum seeds were primed with ZnO NPs (5 and 10 mg/L), prior to planting on potting soil and treatment with high salt (400 mM NaCl). Salt significantly impaired growth by decreasing shoot lengths and fresh weights, causing severe deformation on the anatomical (epidermis and vascular bundle tissue) structure. Element distribution was also affected by salt which increased the Na+/K+ ratio (2.9). Salt also increased oxidative stress markers (reactive oxygen species, malondialdehyde), enzyme activities (SOD, CAT and APX), proline, and soluble sugars. Priming with ZnO NPs stimulated the growth of salt-stressed sorghum plants, which was exhibited by improved shoot lengths, fresh weights, and a well-arranged anatomical structure, as well as a low Na+/K+ ratio (1.53 and 0.58) indicating an improved element distribution. FTIR spectra confirmed a reduction in the degradation of biomolecules correlated with reduced oxidative stress. This study strongly suggests the use of green-synthesized ZnO NPs from A. betulina as potential biostimulants to improve plant growth under abiotic stress.

Comparative analysis of various root active promoters by evaluation of GUS expression in transgenic Arabidopsis.

To prepare various root active promoters for expressing transgenes and prevent gene silencing caused by the repeated use of the same promoter, the expression characteristics of various root active promoters were comparatively evaluated using GUS as a reporter gene. The high-affinity potassium transporter (HKT1;1), the Shaker family potassium ion channel (SKOR), the Shaker family inward rectifying potassium channel (AKT1), the major facilitator superfamily protein (MFS1), and the senescence associated gene 14 (SAG14) promoter from Arabidopsis (Arabidopsis thaliana) were used, and for comparison, four additional constitutive or green tissue specific promoters in the expression vectors were also employed. As the Gateway cloning technology provided by Invitrogen can offer high efficiency and cloning reliability, and easy manipulation of fusion constructs in vitro, our expression vectors are based on binary (destination) vectors compatible with this cloning technique. These destination vectors are also advantageous for stable expression of the transgene, as the heat shock protein terminator is utilized. The AtHKT1;1, SKOR, AKT1, MFS1 and SAG14 promoters were all active in roots but showed slightly different tissue specificities: AtHKT1;1, SKOR, and MFS1 were dominantly active in vascular bundle tissue, while AtHKT1;1 and MFS1- but not SKOR, AKT1, and SAG14-were active in root tips. SKOR showed the strongest root-specificity, and SAG14 showed the highest activity among the five root active promoters. The activity of MFS was developmentally regulated. These destination vectors are now available to express multiple transgenes in transgenic plants, especially in roots.

Host-induced gene silencing of brown planthopper glutathione S-transferase gene enhances rice resistance to sap-sucking insect pests

Host-induced gene silencing (HIGS) of insect growth and development is a promising measure for pest control in practice; the feasibility of disarming insect detoxification of toxic phytochemicals via HIGS of insect detoxification enzymes remains largely unexplored. In this study, a HIGS system was applied to interfere with glutathione S-transferase (GST) gene expression in brown planthopper (BPH, Nilaparvata lugens), a key insect pest in rice of Asia, and regulate rice resistance to the insect. The recombination vector in transgenic plants was expressed in almost all organs, especially in vascular bundle tissues, mesophyll, epidermal cells and leaf sheath sap, but not in xylem. Target BPH NlGST1-1 was successfully integrated into rice genome, the resultant transgenic rice lines harbored a single-copy of BPH NlGST1-1 dsRNA, and expression of NlGST1-1 dsRNA was detected in leaves and leaf sheaths of transgenic lines. However, the content of phytochemical gramine, an inherent alkaloid in gramineous plants, did not change in these transgenic plants. BPH nymphs reared on the transgenic rice expressing NlGST1-1 dsRNA displayed significant reductions in NlGST1-1 transcript expression and GST activity. The transgenic plants significantly retarded relative growth rate of the nymphs and the insect female fecundity, the plants also showed enhanced resistance when attacked by BPH. Our study demonstrated the feasibility of reinforcing gramine-mediated plant defense via HIGS of GSTs in herbivorous insects. HIGS-mediated suppression of the herbivore adaptive mechanism has significant implications for efficiently managing BPH and other pests in rice.

The HKT Transporter Gene from Arabidopsis, AtHKT1;1, Is Dominantly Expressed in Shoot Vascular Tissue and Root Tips and Is Mild Salt Stress-Responsive.

The Arabidopsis high-affinity K+ transporter (AtHKT1;1) plays roles in salt tolerance by unloading Na+ from the root xylem to the xylem parenchyma cells and/or uploading Na+ from the shoot/leaf xylem to the xylem parenchyma cells. To use this promoter for the molecular breeding of salt-tolerant plants, I evaluated the expression profile of the AtHKT1;1 promoter in detail. Approximately 1.1 kbp of sequence upstream from the start codon of AtHKT1;1 was polymerase chain reaction (PCR)-amplified, fused to the β-glucuronidase (GUS) gene, and introduced into Arabidopsis. The resultant transformants were evaluated under nonstressed and salt-stress conditions at the seedling and reproductive stages. Histochemical analysis showed that GUS activity was detected in vascular bundle tissue in roots, hypocotyls, petioles, leaves, and petals, and in root tips. GUS enzyme activity in shoots tended to be higher than that in roots at both stages. After treatment with 50 mM NaCl for 24 h, GUS transcription levels and GUS enzyme activity were enhanced in transgenic lines. These results indicate that the AtHKT1;1 promoter isolated in this study could be useful in expressing transgenes specifically in vascular tissue and root tips, and in a mild salt-stress-responsive manner. The data provide novel insights into the functions of AtHKT1;1.

DSH5, a dihydrosphingosine C4 hydroxylase gene family member, shows spatially restricted expression in rice and is lethal when expressed ectopically.

Dihydrosphingosine C4 hydroxylase (DSH), a diiron-binding membrane enzyme, catalyzes the hydration of dihydrosphingosine and acyl-sphinganine to produce phytosphingosine and phytoceramide, respectively. Rice has two types of DSH homologs: general DSHs, namely DSH1, DSH2 and DSH4, and others that show spatial expression profiles, namely DSH3 and DSH5. The general DSHs exist in many plant species. These DSHs showed similarity in their functions and complemented the yeast sur2D mutation. In contrast, homologs of DSH3 and DSH5 were found only in monocot plants. Phylogenetic analysis placed these DSHs in different clades that are evolutionarily divergent from those of the general DSHs. DSH3 and DSH5 showed low-level expression. DSH5 expression was specifically in vascular bundle tissues. Ectopic expression of DSH5 induced a dwarf phenotype characterized by severe growth inhibition and an increase in the thickness of the leaf body caused by enlargement of bulliform cells in the leaves. However, no significant difference was observed in the amount of sphingolipid species. DSH5 did not complement the yeast sur2D mutation, implying that DSH5 has little effect on sphingolipid metabolism. These findings suggested that DSH3 and DSH5 originated and diverged in monocot plants.

Pretreatment refining leads to constant particle size distribution of lignocellulose biomass in enzymatic hydrolysis

Pretreatment and enzymatic hydrolysis are the two central steps to convert lignocellulosic biomass into fermentable sugars. Here we report a discovery of constant particle size distribution of corn stover and wheat straw in enzymatic hydrolysis after pretreatment. The average particle size of the extensively pretreated corn stover and wheat straw quickly decreases to 20–30 μm in enzymatic hydrolysis and maintains constant without further size shrinking, although the hydrolysis continues to release glucose. The microstructural properties of the lignocellulose biomass pretreated by different processes and severity during the enzymatic hydrolysis were characterized by the particle size analysis, scanning electron microscopy (SEM) and the polarized light microscopy (PLM). The microstructural analysis reveals that the parenchyma tissue of the pretreated corn stover and wheat straw is quickly hydrolyzed, then the vascular bundle tissue is hydrolyzed to short vascular fibers. The fibers maintain a stable structure by the support of residual lignin framework during enzymatic hydrolysis. A structural model of lignocellulose biomass in pretreatment and enzymatic hydrolysis is proposed based on the pretreatment and hydrolysis experiments, as well as the microstructural analysis. This study takes the first insight into the uniform change of lignocellulose structure during pretreatment and enzymatic hydrolysis with the potentials on elevating hydrolysis yield and reconstruction of cell wall structure.

A Novel Wheat Nicotianamine Synthase Gene, TaNAS-D, Confers High Salt Tolerance in Transgenic Arabidopsis

Nicotianamine synthase (NAS) plays a pivotal role in balancing the concentrations of heavy metals in plants, but its characteristics and functions in salt stress responses are not completely understood, particularly in wheat. In this study, the salt-induced gene TaNAS-D was cloned from wheat and characterized. TaNAS-D, localized throughout the cell, is mainly expressed in developed vascular bundle tissues and is responsive to NaCl, ABA, and H2O2 stresses. Overexpression of TaNAS-D in Arabidopsis led to elevated NA levels and enhanced salt stress tolerance, which was demonstrated by higher germination rates and improved growth of TaNAS-D transgenic Arabidopsis plants compared with WT when exposed to salt stress. Further investigation revealed that TaNAS-D transgenic Arabidopsis plants displayed higher K+/Na+ ratios, lower malondialdehyde (MDA) levels, and less ion leakage (IL) consistently accompanied by increased peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities, thereby reducing membrane injury. Moreover, TaNAS-D overexpression under salt stress increased AtSOS1, AtSOS2, AtSOS3, AtFAD5, and AtSAD1 transcript levels. These findings indicate that TaNAS-D plays a positive role in salt tolerance by improving the antioxidant defense system and upregulating salt overly sensitive (SOS) pathway genes.

Immunohistochemical Localization of Endogenous IAA in Peach (Prunus persica L.) Fruit during Development

Peach (Prunus persica L.) is a model species for stone fruit studies within the Rosaceae family. Auxin plays an important role in the development of peach fruit. To reveal the distribution of auxin in the tissues of peach fruit, immunohistochemical localization of IAA was carried out in the seed, mesocarp, and endocarp in developing peach fruit using an anti-indole-3-acetic acid (anti-IAA) monoclonal antibody. A strong IAA signal was observed throughout the outer and inner integument during peach fruit development, and the distribution was zonal. The IAA signal was mainly focused in mucilage layers in the outer integument. The outer integument may function to produce or store IAA in the seed; a strong IAA signal was detected in the cells around the vascular tissue, whereas a weak IAA signal was located in the vascular tissues. In the mesocarp, the cells around the vascular bundle tissue gave rise to an IAA signal that increased in the late phase of fruit growth, which coincided with a significant increase in fruit growth. The distribution of IAA, however, was changed when fruit was treated with auxin transport inhibitors NPA (1-N-naphthylphthalamic acid) or TIBA (2, 3, 5-triiodobenzoic acid); in mesocarp tissues, an IAA signal was detected mainly in vessels of the treated fruit. During the critical period of endocarp lignification, the vessel lignification process was negatively correlated with IAA signal. The present results confirmed that the distribution of IAA was different in various tissues of peach fruit according to the developmental stage. This research provides cytological data for further study of the regulatory mechanism of auxin in peach fruit.

Phytochemical Screening, Pharmacognostic Evaluation and Biological Activity of Amaranthus spinosus L

Herbal medicines possess a great demand in both developed and developing countries as a source of primary health care owing to their attributes having wide biological and medicinal activities, high safety margins and lesser costs. People living in rural areas of Nepal depend largely in the herbal medicines for the treatment. The present study concerns with the study of pharmacognostic characteristics, phytochemical constituents and the biological activity of Amaranthus spinosus L. The hexane, chloroform, ethanolic and aqueous extract of its aerial parts were subjected to preliminary phytochemical analysis and detected saponin, carbohydrate, tannin, protein, glycoside, flavonoid and phenol as phytoconstituents. The transverse section of the stem and leaves showed characteristic vascular bundle tissues. All the extracts were used for testing the antimicrobial activity and brine shrimp lethality. No extract showed the antimicrobial activity and ethanolic extract showed LC50 value of 31.62 ppm. Hexane, chloroform and water extracts were less toxic with LC50 values 236.88 ppm,194.98 ppm and 320.71 ppm respectively.DOI: http://dx.doi.org/10.3126/jmmihs.v1i4.11999Journal of Manmohan Memorial Institute of Health Sciences Vol. 1, Issue 4, 2015Page: 29-34

Transcripts of two ent-copalyl diphosphate synthase genes differentially localize in rice plants according to their distinct biological roles.

Gibberellins (GAs) are diterpenoid phytohormones that regulate various aspects of plant growth. Tetracyclic hydrocarbon ent-kaurene is a biosynthetic intermediate of GAs, and is converted from geranylgeranyl diphosphate, a common precursor of diterpenoids, via ent-copalyl diphosphate (ent-CDP) through successive cyclization reactions catalysed by two distinct diterpene synthases, ent-CDP synthase and ent-kaurene synthase. Rice (Oryza sativa L.) has two ent-CDP synthase genes, OsCPS1 and OsCPS2. It has been thought that OsCPS1 participates in GA biosynthesis, while OsCPS2 participates in the biosynthesis of phytoalexins, phytocassanes A-E, and oryzalexins A-F. It has been shown previously that loss-of-function OsCPS1 mutants display a severe dwarf phenotype caused by GA deficiency despite possessing another ent-CDP synthase gene, OsCPS2. Here, experiments were performed to account for the non-redundant biological function of OsCPS1 and OsCPS2. Quantitative reverse transcription-PCR (qRT-PCR) analysis showed that OsCPS2 transcript levels were drastically lower than those of OsCPS1 in the basal parts, including the meristem of the second-leaf sheaths of rice seedlings. qRT-PCR results using tissue samples prepared by laser microdissection suggested that OsCPS1 transcripts mainly localized in vascular bundle tissues, similar to Arabidopsis CPS, which is responsible for GA biosynthesis, whereas OsCPS2 transcripts mainly localized in epidermal cells that address environmental stressors such as pathogen attack. Furthermore, the OsCPS2 transgene under regulation of the OsCPS1 promoter complemented the dwarf phenotype of an OsCPS1 mutant, oscps1-1. The results indicate that transcripts of the two ent-CDP synthase genes differentially localize in rice plants according to their distinct biological roles, OsCPS1 for growth and OsCPS2 for defence.

Distribution of toxic alkaloids in tissues from three herbal medicine Aconitum species using laser micro-dissection, UHPLC–QTOF MS and LC–MS/MS techniques

Aconite poisoning continues to be a major type of poisoning caused by herbal drugs in many countries. Nevertheless, despite its toxic characteristics, aconite is used because of its valuable therapeutic benefits.The aim of the present study was to determine the distribution of toxic alkaloids in tissues of aconite roots through chemical profiling. Three species were studied, all being used in traditional Chinese Medicine (TCM) and traditional Indian medicine (Ayurveda), namely: Aconitum carmichaelii, Aconitum kusnezoffii and Aconitum heterophyllum.Laser micro-dissection was used for isolation of target microscopic tissues, such as the metaderm, cortex, xylem, pith, and phloem, with ultra-high performance liquid chromatography equipped with quadrupole time-of-flight mass spectrometry (UHPLC–QTOF MS) employed for detection of metabolites. Using a multi-targeted approach through auto and targeted LC–MS/MS, 48 known compounds were identified and the presence of aconitine, mesaconitine and hypaconitine that are the biomarkers of this plant was confirmed in the tissues. These results suggest that the three selected toxic alkaloids were exclusively found in A. carmichaelii and A. kusnezoffii. The most toxic components were found in large A. carmichaelii roots with more lateral root projections, and specifically in the metaderm, cork and vascular bundle tissues. The results from metabolite profiling were correlated with morphological features to predict the tissue specific distribution of toxic components and toxicity differences among the selected species. By careful exclusion of tissues having toxic diester diterpenoid alkaloids, the beneficial effects of aconite can still be retained and the frequency of toxicity occurrences can be greatly reduced.Knowledge of tissue-specific metabolite distribution can guide users and herbal drug manufacturers in prudent selection of relatively safer and therapeutically more effective parts of the root. The information provided from this study can contribute towards improved and effective management of therapeutically important, nonetheless, toxic drug such as Aconite.

Anatomical Structure and Fruit Quality According to the Fruit Developmental Stage as Affected by Gibberellins Treatments in Pyrus pyrifolia Nakai cv. Hanareum

본 연구는 조생종 '한아름'의 기본적인 해부학적 과실 구조 및 과실 품질과 GA 처리 시의 변화를 구명하여 '한아름'의 생리적 특징을 이해하고자 수행하였다. '한아름'의 생육기별 과실 발달을 조사한 결과 만개기의 과실 구조는 바깥쪽으로부터 외표피층, 아표피층, 유조직층, 내표피층으로 구성되어 있으며 5종류의 유관속 조직이 관찰되었다. 코르크층은 무처리구에서는 만개 후 70일, GA 처리구에서는 만개 후 60일경에 형성되었다. '한아름' 품종의 세포분열 기간은 만개 후 40일까지이며 이후에는 세포비대에 의해 과실이 발달하였다. GA 처리에 따른 과실 비대와 조직 발달을 관찰한 결과, GA 처리는 '한아름'의 세포분열에는 영향을 미치지 못하였으며 세포비대를 촉진하는 것으로 조사되었다. 또한 과경부는 세포분열 정지기인 만개 후 40일부터 처리구의 유관속 조직이 무처리구에 비하여 큰 것으로 관찰되어 '한아름' 과실은 GA를 처리할 시 유관속 조직의 발달을 촉진하여 상대적으로 과실로의 양분 공급이 증가하는 것으로 생각되었다. 한편 수확기에 무처리구와 처리구의 평균적인 품질을 비교한 결과, 처리구에서 과중이 높았으나 경도는 낮게 조사되어 '한아름' 과실에 GA를 처리할 경우 수확 후 과실의 저장에 영향을 미칠 것으로 생각되었다. This study was carried out to understand the physiological characteristics of early-matured 'Hanareum' (Pyrus pyrifolia Nakai) pears through anatomical structure and fruit characteristics and also the changes according to gibberellin (GA) treatment. The pericarp at full bloom consists of outer epidermis, hypodermis, parenchyma cell, and inner epidermis from the exterior and five types of vascular bundle tissues. Cork cell layer was formed at 70 days after full bloom (DAFB) in non-treated fruits and formed at 60 DAFB in GA treated fruits. Cell division period was from full bloom (FB) to 40 DAFB and then fruit enlargement was accomplished by the cell growth. Comparison of the fruit enlargement and fruit structure development by GA treatment or non-treatment showed that cell division of 'Hanaerum' fruits did not affect the GA treatment but fruit enlargement was affected cell growth. Fruit stalk of GA treatment fruits was larger than non-treated fruits from 40 DAFB which correspond to the period of the stop of cell division and 'Hanareum' was regarded GA treatment expedite of vascular bundle tissue growth and relatively increased nutrient transport to fruit. In addition to, average fruit quality between the non-treatment and GA treatment showed that fruit weight was higher in fruits treated by GA but firmness was lower and probably was effected fruit storing in 'Hanareum' pear.

English

A fundamental understanding of mango flowering in the tropics is essential to efficiently utilize cropping management systems which could extend both the flowering and crop production seasons. However, the information and appreciation of the floral biology of this popular fruit species is still lacking. Therefore, the objective of this work was to observe the morphology of Chok Anan mango flowers using scanning electron microscope. The Chok Anan mango flower is monoecius where both the male and hermaphrodite flowers exist in the same panicle. The fruit develops from the hermaphrodite flower while the male flower contributes the pollen when pollination occurred. The Chok Anan mango flowers contained five sepals and five petals arranged in a whorl. There were not much differences in the structure of sepals and petals between the male and hermaphrodite flowers. The structure of the petals is not flat but billowy. Both sepals and petals consist of ground parenchyma tissue with laticifer and idioblast cells, starch granules and vascular bundle tissues. Trichomes are present in both sepals and petals. The male flower has the same structure as the hermaphrodite flower except that it does not have carpel. Further study is needed to understand the peculiarities of the floral morphology to allow us to predict mango production. Key words: Pollen, sepal, petal, hermaphrodite, floral biology.

兴安落叶松针叶解剖结构变化及其光合能力对气候变化的适应性

Leaf anatomy,being susceptible to environmental factors,is closely related to physiological functions of the leaf, and also reflects responses and adaptation of the tree to environmental changes. Changes in leaf anatomical structure are bound to change the physiological functions of trees. The same species growing in heterogeneous environment for a long time through natural selection and adaptation will result in variations in morphological and physiological characteristics,forming distinctive geographic populations. In addition,Matrix subjected to environmental stress will affect its offspring growth, developmental and physiological characteristics. Therefore,to understand how the morphological structure of leaves respond and adapt to environmental changes is essential for exploring the response and adaptation mechanism of plants to environmental changes. Dahurian larch( Larix gmelinii Rupr.) is a dominant tree species in boreal forest in China,mainly distributed in northeast China,but going further climate changes may change its existing distribution. There are few studies to distinguish short-term responses of leaf anatomy and physiology from their potential long-term adaptation to climate changes in field. In this study,we conducted a common garden experiment that included six provenances of Dahurian larch with different climate and site conditions with three replicate trees each provenance. The trees were 32 years old,seeded in 1980,and transplanted in 1983 at identical site and climate conditions. We measured leaf anatomical parameters using paraffin section method( i. e.,total leaf thickness,leaf adaxial epidermis cells thickness,leaf abaxial epidermis cells thickness,leaf adaxial mesophyll cells thickness,leaf abaxial mesophyll cells thickness,leaf vascular bundle tissue thickness,leaf endoderm cells thickness,leaf transporting tissue thickness,leaf epidermis cells thickness,leaf mesophyll cells thickness,and photosynthetic physiology( i. e.,photosynthetic capacity [P max-a ],stomatal conductance [g s ],water use efficiency [WUE]) in order to address the question of whether leaf anatomical structure adapts to climate changes and consequently results in physiological adaptation. The results showed that the thickness of epidermis cells,mesophyll cells, transmission tissue cells,vascular cells and endothelial cells,and the total thickness of the needles differed significantly among the provenances( P 0. 05). There was a significant difference in the proportion of thickness of each anatomical part. The thickness of mesophyll cell accounted for the largest proportion,with an average proportion ranging from 38. 4% to 43. 3%. The thickness of mesophyll cells was positively correlated( P0. 05) with P max-a,g s,and WUE. The thickness of mesophyll cells and epidermal cells,the total thickness of the needles,and the proportions of thickness of mesophyll cells or epidermal cells in the total thickness of the needle were all positively correlated with the aridity index( the ratio of mean annual evaporation to mean annual precipitation) at the origins of the provenances. These results suggest that needles of the Dahurian larch trees from different provenances alter their anatomical structures significantly due to adaptation to local climate conditions,and accordingly change their physiological functions such as photosynthesis and water use efficiency.