ABSTRACT
The present study evaluates the phytotoxic effects of phloretin, a prevalent secondary metabolite of apple trees, on the broadleaf weed Capsella bursa-pastoris (L.) Medik. known for its resistant myxospermous seeds that form a long-lasting soil bank. The results indicate a significant, dose-dependent inhibitory effect of phloretin on the growth and morphological parameters of weed seedlings grown in vitro. Although the applied phloretin concentrations (250-1000 µM) were not lethal to the C. bursa-pastoris seedlings after two weeks, the metabolism of the seedlings was impaired, resulting in an accumulation of lipid droplets in the root tips and root hairs. Histochemical analysis shows deposits of phenols in the root epidermal cells, which are probably aggregates of phloretin or its metabolic derivatives. The accumulation of pectin in the cell walls of root border cells in phloretin-treated seedlings indicates an attempt to reduce the uptake of phloretin and reduce its concentration in the cells. Inhibition of shoot growth associated with chlorosis and reduced photosynthetic pigment content is a consequence of seedling exposure to phloretin. This study provides a basis for further evaluation of phloretin as a new bioherbicidal compound and for elucidating the mechanism underlying its phytotoxic activity.
ABSTRACT
Apple species are the unique naturally rich source of dihydrochalcones, phenolic compounds with an elusive role in planta, but suggested auto-allelochemical features related to "apple replant disease" (ARD). Our aim was to elucidate the physiological basis of the phytotoxic action of dihydrochalcone phloretin in the model plant Arabidopsis and to promote phloretin as a new prospective eco-friendly phytotoxic compound. Phloretin treatment induced a significant dose-dependent growth retardation and severe morphological abnormalities and agravitropic behavior in Arabidopsis seedlings. Histological examination revealed a reduced starch content in the columella cells and a serious disturbance in root architecture, which resulted in the reduction in length of meristematic and elongation zones. Significantly disturbed auxin metabolome profile in roots with a particularly increased content of IAA accumulated in the lateral parts of the root apex, accompanied by changes in the expression of auxin biosynthetic and transport genes, especially PIN1, PIN3, PIN7, and ABCB1, indicates the role of auxin in physiological basis of phloretin-induced growth retardation. The results reveal a disturbance of auxin homeostasis as the main mechanism of phytotoxic action of phloretin. This mechanism makes phloretin a prospective candidate for an eco-friendly bioherbicide and paves the way for further research of phloretin role in ARD.
ABSTRACT
The aim of this study was to develop a fast, reliable and true-to-type protocol for in vitro plant regeneration and long-term storage of horned pansy (Viola cornuta L). Seed germination over 60% was recorded after 12 weeks of growth at 10 °C or 4 °C. Calli formation and shoot induction were obtained in petiole and hypocotyl culture on half-strength MS mineral salts with full concentration of Na-FeEDTA and vitamins (½MS medium) with 2,4-dichlorophenoxyacetic acid (2,4-D, 0.1 mg/L) and 6-benzylaminopurine (BAP, 2.0 mg/L) and leaf culture on ½MS medium with thidiazuron (TDZ,1.0 mg/L). The highest frequency of adventitious shoot induction (50%) with six shoots/explant was achieved in hypocotyl culture from top hypocotyl segments, close to epicotyl which was grown 8 weeks at 16 h light/8 h dark photoperiod. Subsequent shoot multiplication was achieved on ½MS medium with α-naphthaleneacetic acid (NAA, 0.1 or 0.5 mg/L) and BAP (1.0 mg/L). Rooting of shoots was obtained on ½MS medium with low concentration (0.1 mg/L) of auxins: indole-3-acetic acid (IAA), indole-3-butyric acid (IBA) or NAA, or without growth regulators. In vitro-derived plantlets were acclimatized under greenhouse conditions. All plants developed normally, bloomed and set seeds. Shoot tips were cryopreserved succssefully using modified plant vitrification 3 (PVS3-based vitrification procedure). Cold acclimation for 2 weeks significantly improved shoot regrowth (64%) after thawing in comparison to non-acclimated shoots (39%). Clonal fidelity of regenerated plantlets at ploidy level was confirmed by chromosome counting. The presented protocol can be useful for mass propagation, genetic transformation studies and long-term storage of valuable Viola spp.
ABSTRACT
INTRODUCTION: Orthodontic diagnosis includes the interpretation of the relations between the craniofacial and cervical system, given the potential impact of the irregularities from one system to another. OBJECTIVE: The aim of this study was to examine morphological characteristics of the cervical spine, depending on the parameters of the vertical craniofacial growth and gender in adult subjects. METHODS: The sample comprised lateral cephalograms of 120 subjects with different vertical facial growth, aged 17.5-35 years. Measured parameters were the following: anterior and posterior vertebral body height (ABHC2-C5, PBHC2-C5), anterior and posterior intervertebral space (AISC2-C5, PISC2-C5), distance between vertebrae and point sella (SC2, SC3, SC4), pterygomaxillare (PmC2), gonion (GoC2) and basion (BaC4); cervical spine angulation (OPT/CVT) and inclination (OPT/HOR, CVT/HOR). RESULTS: Results showed that subjects with anterior facial growth rotation have greater values for BaC4, OPT/HOR, CVT/HOR, OPT/CVT, anterior and posterior vertebral body heights and intervertebral spaces, and lower values for GoC2 and PmC2. Higher values in males were found for anterior and posterior vertebral body heights, distances SC2, SC3, SC4, and BaC4. In females, the greater values were found for GoC2 and OPT/CVT. CONCLUSION: Subjects with anterior facial growth rotation have greater cervical spine inclination and angulation, higher cervical vertebrae and intervertebral spaces, longer upper cervical spines and shorter distances GoC2 and PmC2. Males show smaller cervical column curvature, but higher cervical vertebrae and greater length of the upper cervical spine.