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Light and gravity coordinately regulate the directional growth of plants. Arabidopsis Gravitropic in the Light 1 (GIL1) inhibits the negative gravitropism of hypocotyls in red and far-red light, but the underlying molecular mechanisms remain elusive. Our study found that GIL1 is a plasma membrane-localized protein. In endodermal cells of the upper part of hypocotyls, GIL1 controls the negative gravitropism of hypocotyls. GIL1 directly interacts with PIN3 and inhibits the auxin transport activity of PIN3. Mutation of PIN3 suppresses the abnormal gravitropic response of gil1 mutant. The GIL1 protein is unstable in darkness but it is stabilized by red and far-red light. Together, our data suggest that light-stabilized GIL1 inhibits the negative gravitropism of hypocotyls by suppressing the activity of the auxin transporter PIN3, thereby enhancing the emergence of young seedlings from the soil., (© 2024 The Author(s). Journal of Integrative Plant Biology published by John Wiley & Sons Australia, Ltd on behalf of Institute of Botany, Chinese Academy of Sciences.)

Hypocotyl growth during seedling emergence is a crucial developmental transition influenced by light and phytohormones such as ethylene. Ethylene and light antagonistically control hypocotyl growth in either continuous light or darkness. However, how ethylene and light regulate hypocotyl growth, including seedling emergence, during the dark-to-light transition remains elusive. Here, we show that ethylene and light cooperatively stimulate a transient increase in hypocotyl growth during the dark-to-light transition via the light-mediated stabilization of 1-aminocyclopropane-1-carboxylic acid (ACC) synthases (ACSs), the rate-limiting enzymes in ethylene biosynthesis. We found that, in contrast to the known inhibitory role of light in hypocotyl growth, light treatment transiently increases hypocotyl growth in wild-type etiolated seedlings. Moreover, ACC, the direct precursor of ethylene, accentuates the effects of light on hypocotyl elongation during the dark-to-light transition. We determined that light leads to the transient elongation of hypocotyls by stabilizing the ACS5 protein during the dark-to-light transition. Furthermore, biochemical analysis of an ACS5 mutant protein bearing an alteration in the C-terminus indicated that light stabilizes ACS5 by inhibiting the degradation mechanism that acts through the C-terminus of ACS5. Our study reveals that plants regulate hypocotyl elongation during seedling establishment by coordinating light-induced ethylene biosynthesis at the post-translational level. Moreover, the stimulatory role of light on hypocotyl growth during the dark-to-light transition provides additional insights into the known inhibitory role of light in hypocotyl development., (© 2019 The Authors The Plant Journal © 2019 John Wiley & Sons Ltd.)

Plants detect neighboring vegetation as potential competitors for resources. Vegetation proximity is perceived by changes in the red (R) to far-red (FR) ratio (R:FR) through the phytochrome photoreceptors. To face this challenge, many plants have evolved the strategy to avoid shade, displaying a series of responses known as the shade avoidance syndrome (SAS). The SAS responses have been mostly studied at the seedling stage, and cover hypocotyl elongation as well as cotyledon and primary leaf expansion. In adult stages, SAS responses include an increase in petiole elongation and a decrease in leaf expansion, and an increase in plant height. Thus, the analysis of these responses provides a valuable and simple way to study how vegetation proximity affects plant development in both seedlings and adult plants. Here we describe a simple protocol to simulate shade in the laboratory and to evaluate these responses. Overall, our protocol can be easily used to expand the set of SAS responses of plants at different stages of development.

Adventitious roots (AR) are de novo formed roots that emerge from any part of the plant or from callus in tissue culture, except root tissue. The plant tissue origin and the method by which they are induced determine the physiological properties of emerged ARs. Hence, a standard method encompassing all types of AR does not exist. Here we describe a method for the induction and analysis of AR that emerge from the etiolated hypocotyl of dicot plants. The hypocotyl is formed during embryogenesis and shows a determined developmental pattern which usually does not involve AR formation. However, the hypocotyl shows propensity to form de novo roots under specific circumstances such as removal of the root system, high humidity or flooding, or during de-etiolation. The hypocotyl AR emerge from a pericycle-like cell layer surrounding the vascular tissue of the central cylinder, which is reminiscent to the developmental program of lateral roots. Here we propose an easy protocol for in vitro hypocotyl AR induction from etiolated Arabidopsis seedlings.

In plants, the cell wall is a complex and dynamic structure comprising high molecular weight carbohydrates and proteins. The cell wall plays an important role in several stages of the plant life cycle, including cell division, elongation and differentiation. The DUF642 family of cell wall proteins is highly conserved in spermatophytes and might be involved in pectin structural modifications. Particularly, At2g41800 is one of the most highly induced genes during the M/G1 phases of the cell cycle, and the protein encodes by this gene has been detected in cell wall proteomes of cell suspension cultures. In the present study, the expression of At2g41800 (TEB) was confirmed in primary and lateral roots, stigmatic papillae and hypocotyls. Subcellular localization studies showed that TEB is located in the cell wall. The root length and lateral root density were not affected in either of the two teb mutants studied, but the length of the hypocotyls from seedlings grown under light and dark conditions was increased. Immunogold labelling studies using JIM5 antibodies on sections of hypocotyl epidermal cells showed an important reduction of gold particles in teb mutants. The results suggested that TEB is involved in hypocotyl elongation., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Copyright of Journal of Agriculture & Nature / Kahramanmaraş Sütçü İmam Üniversitesi Tarım & Doğa Dergisi is the property of Kahramanmaras Sutcu Imam Universitesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Vivipary is not a rare finding in papaya fruit. However, this short communication describes the unusual germination of seedling within intra-ovarian ovary. The seedling is attached at two ends of the immature ovary: by radicle at one end, and by elongated tubular structure at the other end. The tubular structure, probably a hypocotyl, mimics an umbilical cord connecting the growing fetus with that of placenta in human embryonic development. [ABSTRACT FROM AUTHOR]

Targeted insertion of transgenes in plants is still challenging and requires further technical innovation. In the present study, we chose the tomato DFR gene involved in anthocyanin biosynthesis as a landing pad for targeted transgene insertion using CRISPR-Cas9 in a two-step strategy. First, a 1013 bp was deleted in the endogenous DFR gene. Hypocotyls and callus of in vitro regenerated plantlets homozygous for the deletion were green instead of the usual anthocyanin produced purple colour. Next, standard Agrobacterium-mediated transformation was used to target transgene insertion at the DFR landing pad in the dfr deletion line. The single binary vector carried two sgRNAs, a donor template containing two homology arms of 400 bp, the previously deleted DFR sequence, and a NptII expression cassette. Regenerating plantlets were screened for a purple-colour phenotype indicating that DFR function had been restored. Targeted insertions were identified in 1.29% of the transformed explants. Thus, we established an efficient method for selecting HDR-mediated transgene insertion using the CRISPR-Cas9 system in tomato. The visual screen used here facilitates selection of these rare gene targeting events, does not necessitate the systematic PCR screening of all the regenerating material and can be potentially applied to other crops. [ABSTRACT FROM AUTHOR]

Abstract Enzyme β-galactosidase (EC 3.2.1.23) is known to influence vascular differentiation during early vegetative growth of plants, but its role in hypocotyl development is not yet fully understood. We generated the hypocotyl transcriptome data of a hypocotyl-defect jute (Corchorus capsularis L.) mutant (52,393 unigenes) and its wild-type (WT) cv. JRC-212 (44,720 unigenes) by paired-end RNA-seq and identified 11 isoforms of β-galactosidase , using a combination of sequence annotation, domain identification and structural-homology modeling. Phylogenetic analysis classified the jute β-galactosidases into six subfamilies of glycoside hydrolase-35 family, which are closely related to homologs from Malvaceous species. We also report here the expression of a β-galactosidase of glycoside hydrolase-2 family that was earlier considered to be absent in higher plants. Comparative analysis of domain structure allowed us to propose a domain-centric evolution of the five classes of plant β-galactosidases. Further, we observed 1.8–12.2-fold higher expression of nine β-galactosidase isoforms in the mutant hypocotyl, which was characterized by slower growth, undulated shape and deformed cell wall. In vitro and in vivo β-galactosidase activities were also higher in the mutant hypocotyl. Phenotypic analysis supported a significant (P ≤ 0.01) positive correlation between enzyme activity and undulated hypocotyl. Taken together, our study identifies the complete set of β-galactosidases expressed in the jute hypocotyl, and provides compelling evidence that they may be involved in cell wall degradation during hypocotyl development. Graphical abstract Image 1 Highlights • We generated hypocotyl transcriptomes from mutant and wild-type jute annotating 39,076 genes. • We characterized the complete array of β-galactosidases expressed in jute hypocotyl. • A domain-centric classification of plant β-galactosidases helps to explain their evolution. • We elucidated the evolution of a prokaryotic β-galactosidase previously undescribed in plant. • Our study indicates a crucial role of β-galactosidase in hypocotyl development. [ABSTRACT FROM AUTHOR]

Key message: DSBs differently affect endoreduplication and organ size in radish cotyledons and hypocotyls in different light conditions, suggesting that DSBs-mediated endoreduplication varies based on different developmental and environmental cues.Abstract: Endoreduplication induced by DNA double strand breaks (DSBs) in Arabidopsis thaliana roots and cultured cells has been reported in recent years. In this study, we investigated whether DSBs-mediated endoreduplication also occurs in other tissues, such as cotyledons and hypocotyls of radish (Raphanus sativus var. longipinnatus) plants. To induce DSBs, UV irradiation and Zeocin treatment were applied to in vitro-cultured radish seedlings, and ploidy distribution of the treated tissues was analyzed by flow cytometry. Consequently, frequencies of the higher ploidy (8C) cells and cycle values in the cotyledon tissues increased with increasing doses of UV irradiation and concentrations of Zeocin, irrespective of light conditions. UV-stimulated endoreduplication was also observed in four Brassica species. In hypocotyls, UV treatments decreased the frequencies of higher ploidy (32C) cells and cycle values in dark-grown seedlings, whereas Zeocin treatments increased the frequencies of higher ploidy (16C and 32C) cells and cycle values in light- and dark-grown seedlings. Among the treatments, organ sizes did not simply correlate with cycle values. The effects of treatments on endoreduplication and organ size differed based on organ and light conditions, indicating that DSBs-mediated endoreduplication may involve a multifaceted response to different developmental and environmental cues. [ABSTRACT FROM AUTHOR]

Regulation of protein function by phosphorylation and dephosphorylation is an important mechanism in many cellular events. The phototropin blue-light photoreceptors, plant-specific AGCVIII kinases, are essential for phototropic responses. Members of the D6 PROTEIN KINASE (D6PK) family, representing a subfamily of the AGCVIII kinases, also contribute to phototropic responses, suggesting that possibly further AGCVIII kinases may potentially control phototropism. The present study investigates the functional roles of Arabidopsis (Arabidopsis thaliana) AGCVIII kinases in hypocotyl phototropism. We demonstrate that D6PK family kinases are not only required for the second but also for the first positive phototropism. In addition, we find that a previously uncharacterized AGCVIII protein, AGC1-12, is involved in the first positive phototropism and gravitropism. AGC1-12 phosphorylates serine residues in the cytoplasmic loop of PIN-FORMED 1 (PIN1) and shares phosphosite preferences with D6PK. Our work strongly suggests that the D6PK family and AGC1-12 are critical components for both hypocotyl phototropism and gravitropism, and that these kinases control tropic responses mainly through regulation of PIN-mediated auxin transport by protein phosphorylation. [ABSTRACT FROM AUTHOR]

Background: Lignin and lignans are both derived from the monolignol pathway. Despite the similarity of their building blocks, they fulfil different functions in planta. Lignin strengthens the tissues of the plant, while lignans are involved in plant defence and growth regulation. Their biosyntheses are tuned both spatially and temporally to suit the development of the plant (water conduction, reaction to stresses). We propose to study the general molecular events related to monolignol-derived product biosynthesis, especially lignin. It was previously shown that the growing hemp hypocotyl (between 6 and 20 days after sowing) is a valid system to study secondary growth and the molecular events accompanying lignification. The present work confirms the validity of this system, by using it to study the regulation of lignin and lignan biosynthesis. Microscopic observations, lignin analysis, proteomics, together with in situ laccase and peroxidase activity assays were carried out to understand the dynamics of lignin synthesis during the development of the hemp hypocotyl. Results: Based on phylogenetic analysis and targeted gene expression, we suggest a role for the hemp dirigent and dirigent-like proteins in lignan biosynthesis. The transdisciplinary approach adopted resulted in the gene- and protein-level quantification of the main enzymes involved in the biosynthesis of monolignols and their oxidative coupling (laccases and class III peroxidases), in lignin deposition (dirigent-like proteins) and in the determination of the stereoconformation of lignans (dirigent proteins). Conclusions: Our work sheds light on how, in the growing hemp hypocotyl, the provision of the precursors needed to synthesize the aromatic biomolecules lignin and lignans is regulated at the transcriptional and proteomic level. [ABSTRACT FROM AUTHOR]

The production of shoots from roots (adventitious bud and shoot formation, root sprouting) first attracted attention in the 19th century as a morphological rarity. At that time, the first checklists of plants capable of root sprouting were compiled. Since then, experiments have proven that the ability to produce buds on roots serves the purpose of bud bank formation or represents a mode of clonal growth. The former enables resprouting after injury whereas the latter facilitates foraging for nutrients and vegetative multiplication. However, only a small proportion of root-sprouters have been studied so far, and for most of them we lack detailed data on the anatomy, morphology, ecology and physiology of adventitious shoot formation. These knowledge gaps hinder further understanding of their ecology and evolution. To support researchers interested in adventitious bud and shoot formation in any field of plant science, we compiled a list of plants considered capable of root sprouting based on the literature and the CLO-PLA database for the flora of the Czech Republic. Here we provide basic comparisons concerning the distribution of root sprouting ability among life history types, plants differing in rarity and invasive status, and taxonomic groups. Altogether 342 plant species are reported to be root-sprouters, i.e. 10% of the Czech flora. Root-sprouters are most commonly found among woody plants, less so among non-clonal perennial herbs, biennials and clonal herbs, and least commonly among annuals. Root-sprouters are more common among alien plants (especially woody ones) than among red-listed plants. Root sprouting usually plays a supplementary (facultative) or regenerative role in the plant life cycle. Root-sprouters occur in 64 families, mostly of dicots. The greatest number of root-sprouters belong to the Asteraceae and Rosaceae families (41). We have only rudimentary information on 145 species out of the 342 (42%) species that are regarded as root-sprouters. [ABSTRACT FROM AUTHOR]

A plant regeneration protocol was established from hypocotyl explants of in vitro grown seedlings of Asparagus officinalis and in vitro-proliferated shoots, respectively through either somatic embryogenesis or embryogenic callus. Types of auxins and cytokinins play an important role for producing somatic embryos. Friable calli with somatic embryos developed well in MS medium supplemented with 2.0-4.0 μM 6- benzylaminopurine (BAP) and 1.0-4.0 μM 2,4- dichlorophenoxyacetic acid (2,4-D), 1- naphthaleneacetic acid (NAA) or indole-3-butyric acid (IBA). The highest 96.3% embryogenic calli and maximum number of 60.0 somatic embryos formation were obtained from each explant when the MS medium was fortified with 4.0 μM BAP and 2.0 μM 2,4-D. The best embryo germination occurred in 1.0 μM BAP supplemented ½ strength MS medium. The highest 95.2% of shoot proliferation was observed in embryogenic calli in MS medium containing 2.0 μM BAP and 1.0 μM IBA or NAA. In vitro-grown shoots were rooted in ½ strength MS medium with 0.5-4.0 μM IBA. Regenerants were transferred to vermicompost and successfully established under an ex vitro environment in garden soil with 75.0% survival rate. [ABSTRACT FROM AUTHOR]

Imaging analysis was carried out during the gravitropic response of etiolated Arabidopsis hypocotyls, using an IAA19 promoter fusion of destabilized luciferase as a probe. From the bright-field images we obtained the local deflection angle to the vertical, A, local curvature, C, and the partial derivative of C with respect to time, $$\partial C/\partial t$$ . These were determined every 19.9 µm along the curvilinear length of the hypocotyl, at ~10 min intervals over a period of ~6 h after turning hypocotyls through 90° to the horizontal. Similarly from the luminescence images we measured the luminescence intensity of the convex and concave flanks of the hypocotyl as well as along the median of the hypocotyl, to determine differential expression of auxin-inducible IAA19. Comparison of these parameters as a function of time and curvilinear length shows that the gravitropic response is composed of three successive elements: the first and second curving responses and a decurving response (autostraightening). The maximum of the first curving response occurs when A is 76° along the entire length of the hypocotyl, suggesting that A is the sole determinant in this response; in contrast, the decurving response is a function of both A and C, as predicted by the newly-proposed graviproprioception model (Bastien et al., Proc Natl Acad Sci USA 110:755-760, 2013). Further, differential expression of IAA19, with higher expression in the convex flank, is observed at A = 44°, and follows the Sachs' sine law. This also suggests that IAA19 is not involved in the first curving response. In summary, the gravitropic response of Arabidopsis hypocotyls consists of multiple elements that are each determined by separate principles. [ABSTRACT FROM AUTHOR]

Background and Aims The underground saxophone stem systems produced by seedlings of certain palm species show peculiar growth patterns and distinctive morphologies, although little information is available concerning their development and function. We studied the ontogenesis of the saxophone stem in Acrocomia aculeata, an important neotropical oleaginous palm, and sought to experimentally define its function. Methods Morpho-anatomical evaluations were performed during 240 d on seedlings using traditional methodologies. The tuberous region of the structure was submitted to histochemical tests and evaluated by transmission electron microscopy. The aerial portions of 130 1- to 3-year-old greenhouse plants were removed and their continuous growth capacity was evaluated after 30 d. Severed saxophone stems were also stored at room temperature (average 25 °C) for up to 90 d and then cultured for 60 d to evaluate root and shoot emission. Key Results The development of the saxophone stem is distinct from other underground systems previously described, and involves three processes: growth and curvature of the cotyledonary petiole, expansion and curvature of the hypocotyl, and expansion of the plumule internodes. The tuberous region stores water and starch, as well as lesser amounts of mucilage and oil. Growth of the aerial portion occurred in 84 % of the separated saxophone stems and in 53 % of the stems held in storage. Conclusions The saxophone stem represents an important adaptation of A. aculeata to anthropogenically impacted and/or dry environments by promoting the burial of both the shoot meristem and storage reserves, which allows the continuous growth of aerial organs. [ABSTRACT FROM AUTHOR]

An emerging challenge in plant biology is to develop qualitative and quantitative measures to describe the appearance of plants through the integration of mathematics and biology. A major hurdle in developing these metrics is finding common terminology across fields. In this review, we define approaches for analyzing plant geometry, topology, and shape, and provide examples for how these terms have been and can be applied to plants. In leaf morphological quantifications both geometry and shape have been used to gain insight into leaf function and evolution. For the analysis of cell growth and expansion, we highlight the utility of geometric descriptors for understanding sepal and hypocotyl development. For branched structures, we describe how topology has been applied to quantify root system architecture to lend insight into root function. Lastly, we discuss the importance of using morphological descriptors in ecology to assess how communities interact, function, and respond within different environments. This review aims to provide a basic description of the mathematical principles underlying morphological quantifications. [ABSTRACT FROM AUTHOR]

Whilst plastids are fundamental to many aspects of plant biology and the production of enhanced crop cultivars, research into the dynamics of non-green plastids has remained somewhat disregarded by the scientific community compared to chloroplasts. They are equally pivotal to normal plant development however, and are now increasingly becoming the focus of research made possible by genetic manipulation and reporter gene constructs. The total plastid content of all plant cells originates from small, undifferentiated plastids termed proplastids found within the meristematic regions of both root and shoot tissue. The cellular regulatory mechanisms controlling the development of plastids in young tissues are poorly understood, especially in the case of non-green plastids in roots. This investigation consequently aimed to elucidate the differences in plastid content, morphology and subcellular localization within epidermal cells derived from the root and shoot apical meristems (RAM and SAM respectively) of Arabidopsis thaliana. Quantification of non-green plastids was facilitated via the use of confocal laser scanning microscopy in conjunction with the expression of plastid-targeted green fluorescent protein driven by a constitutive promoter. Characterization of early seedling development and tissue diversification was also achieved by assessing epidermal cell size relative to developmental progression, ultimately facilitating comparative analyses of plastid dynamics on both a temporal and tissuevarietal basis. The number of plastids in epidermal cells within RAM-derived tissue was shown to increase across regions of cell division before being regulated throughout subsequent zones of elongation and maturing root tissue. In contrast, epidermal cells of the hypocotyl exhibit a more generalized increase in plastid number and less strict maintenance of cell plan area coverage during tissue expansion. The findings presented here suggest the functioning of distinct mechanisms regulating plastid division and growth in relation to cell size within shoot and root apical meristem-derived tissues. [ABSTRACT FROM AUTHOR]

Numerous studies deal with composition and molecular processes involved in primary cell wall formation and alteration in Arabidopsis. However, it still remains difficult to assess the relation between physiological properties and mechanical function at the cell wall level. The thin and fragile structure of primary cell walls and their large biological variability, partly related to structural changes during growth, make mechanical experiments challenging. Since, to the best of our knowledge, there is no reliable data in the literature about how the properties of the fully elongated zone of hypocotyls change with age. We studied in a series of experiments on two different seed batches the tensile properties the region below the growth zone of 4 to 7 day old etiolated Arabidopsis hypocotyls. Additionally, we analysed geometrical parameters, hypocotyl density and cellulose content as individual traits and their relation to tissue mechanics. No significant differences of the mechanical parameters of the non-growing region between 5–7 day old plants could be found whereas in 4 day old plants both tensile stiffness and ultimate tensile stress were significantly lower than in the older plants. Furthermore hypocotyl diameters and densities remain almost the same for 5, 6 and 7 day old seedlings. Naturally, hypocotyl lengths increase with age. The evaluation whether the choice–age or length—influences the mechanical properties showed that both are equally applicable sampling parameters. Additionally, our detailed study allows for the estimation of biological variability, connections between mechanics and hypocotyl age could be established and complement the knowledge on biochemistry and genetics affecting primary plant cell wall growth. The application of two different micromechanical devices for testing living Arabidopsis hypocotyls allows for emphasizing and discussing experimental limitations and for presenting a wide range of possibilities to address current and future questions related to plant cell wall mechanics, synthesis and growth in combination with molecular biology methodologies. [ABSTRACT FROM AUTHOR]

Summary Plants adjust their growth according to gravity. Gravitropism involves gravity perception, signal transduction, and asymmetric growth response, with organ bending as a consequence [ 1 ]. Asymmetric growth results from the asymmetric distribution of the plant-specific signaling molecule auxin [ 2 ] that is generated by lateral transport, mediated in the hypocotyl predominantly by the auxin transporter PIN-FORMED3 (PIN3) [ 3–5 ]. Gravity stimulation polarizes PIN3 to the bottom sides of endodermal cells, correlating with increased auxin accumulation in adjacent tissues at the lower side of the stimulated organ, where auxin induces cell elongation and, hence, organ bending. A curvature response allows the hypocotyl to resume straight growth at a defined angle [ 6 ], implying that at some point auxin symmetry is restored to prevent overbending. Here, we present initial insights into cellular and molecular mechanisms that lead to the termination of the tropic response. We identified an auxin feedback on PIN3 polarization as underlying mechanism that restores symmetry of the PIN3-dependent auxin flow. Thus, two mechanistically distinct PIN3 polarization events redirect auxin fluxes at different time points of the gravity response: first, gravity-mediated redirection of PIN3-mediated auxin flow toward the lower hypocotyl side, where auxin gradually accumulates and promotes growth, and later PIN3 polarization to the opposite cell side, depleting this auxin maximum to end the bending. Accordingly, genetic or pharmacological interference with the late PIN3 polarization prevents termination of the response and leads to hypocotyl overbending. This observation reveals a role of auxin feedback on PIN polarity in the termination of the tropic response. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Key message: ABC1K1 functions as a novel negative regulator downstream of phyB and HY5 in red light-mediated Arabidopsis development. Abstract: Light is a key environmental factor for plant morphogenesis. To understand the role of ACTIVITY OF BC1 COMPLEX KINASE (ABC1K) family members in light-mediated Arabidopsis development, we examined the phenotype of abc1k mutants under various light conditions. We show that abc1k1 mutants display significantly short hypocotyls specifically under continuous red light and this effect is more apparent under higher red light fluence rates. The expression of PHYTOCHROME- INTERACTING FACTORs ( PIFs), transcription factors in red light signaling, is repressed in abc1k1 mutants under continuous red light. The expression pattern of ABC1K1 is independent of light conditions. Furthermore, genetic analysis indicates that abc1k1 almost completely suppresses the long hypocotyl phenotype of phyB and hy5. However, the mutation of ABC1K3, one homolog of ABC1K1, reverses the inhibition of hypocotyl elongation in phyB and hy5 by abc1k1. Together, our research describes novel characteristics for ABC1K1 in seedling stage and defines it as a novel negative component in red light-mediated Arabidopsis development. [ABSTRACT FROM AUTHOR]

Tung tree [Vernicia fordii (Hemsl.) Airy-Shaw] is one of the most important woody oil plants and provides the sole source of tung oil widely used in the industry. An efficient and reproducible in vitro regeneration method is required for genetic transformation in tung tree. In this study, we reported an effective and reproducible regeneration method for tung tree using hypocotyl explants. The optimum condition for callus induction was observed in woody plant medium (WPM) supplemented with 5.0 mg L-1 6-benzyladenine (BA), 1.0 mg L-1 kinetin (KT) and 0.1 mg L-1 α-naphthaleneacetic acid (NAA), with an induction rate of 100%. High frequency of shoot initiation was achieved in WPM supplemented with 1.0 mg L-1 6-BA, 0.05 mg L-1 NAA and 2.0 mg L-1 gibberellic acid (GA3), with an induction rate of 82.46%. Efficient shoot proliferation was obtained in WPM supplemented with 2.0 mg L-1 KT, 0.05 mg L-1 indole-3-acetic acid (IAA), and 2.0 mg L-1 GA3, with a multiplication index of 6.8. Shoot elongation and strengthening was noted in WPM supplemented with 1.0 mg L-1 NAA and 2.0 mg L-1 GA3. High rooting rate of 97.1% was achieved in 1/2 Murashige and Skoog (1962) (MS) medium supplemented with 0.1 mg L-1 indolebutyric acid (IBA). The well-rooted in vitro regenerated plantlets were successfully transferred to mixed substrates of peat moss: perlite: loess (1:1:1) and their survival rate reached 91.67% under natural environment. The efficient and reproducible in vitro regeneration method is established from hypocotyl explants, which could be applied for agrobacterium-mediated genetics transformation in tung tree. [ABSTRACT FROM AUTHOR]

In high density of vegetation, plants detect neighbors by perceiving changes in light quality through phytochrome photoreceptors. Close vegetation proximity might result in competition for resources, such as light. To face this challenge, plants have evolved two alternative strategies: to either tolerate or avoid shade. Shade-avoiding species generally adapt their development by inducing hypocotyl, stem, and petiole elongation, apical dominance and flowering, and decreasing leaf expansion and yield, a set of responses collectively known as the shade avoidance syndrome (SAS). The SAS responses have been mostly studied at the seedling stage, centered on the increase of hypocotyl elongation. After compiling the main findings about SAS responses in seedlings, this review is focused on the response to shade at adult stages of development, such as petioles of adult leaves, and the little information available on the SAS responses in reproductive tissues. We discuss these responses based on the knowledge about the molecular mechanisms and components with a role in regulating the SAS response of the hypocotyls of Arabidopsis thaliana. The transcriptional networks involved in this process, as well as the communication among the tissues that perceive the shade and the ones that respond to this stimulus will also be briefly commented. [ABSTRACT FROM AUTHOR]

Gravitropic bending of seedlings of Arabidopsis thaliana in response to centrifugal accelerations was determined in a range between 0.0025 and 4 × g to revisit and validate the so-called resultant law, which claims that centrifugation causes gravitropic organs to orient parallel to the resultant stimulus vector. We show here for seedlings of A. thaliana that this empirical law holds for hypocotyls but surprisingly fails for roots. While the behavior of hypocotyls could be modeled by an arc tangent function predicted by the resultant law, roots displayed a sharp maximum at 1.8 × g that substantially overshoots the predicted value and that represents a novel phenomenon, diagravitropism elicited by centrifugal acceleration. The gravitropic bending critically depended on the orientation of the seedling relative to the centrifugal acceleration. If the centrifugal vector pointed toward the cotyledons, gravitropic bending of hypocotyls and roots was substantially enhanced. The complex behavior of Arabidopsis seedlings provides strong evidence that gravitropic bending entails a cosine component (longitudinal stimulus) to which the seedlings were more sensitive than to the classical sine component. The absolute gravitropic thresholds of hypocotyls and roots were determined in a clinostat-centrifuge and found to be below 0.015 × g . A tropism mutant lacking the EHB1 protein, which interacts with ARF-GAP (ARF GTPase-activating protein) and thus indirectly with a small ARF-type G protein, displayed a lower gravitropic threshold for roots and also enhanced bending, while the responses of the hypocotyls remained nearly unaffected. [ABSTRACT FROM AUTHOR]

Soybean is a nutritionally important crop, but exhibits reduced growth and yields under flooding stress. To investigate soybean responses during post-flooding recovery, a gel-free proteomic technique was used to examine the protein profile in the hypocotyl. Two-day-old soybeans were flooded for 2 days and hypocotyl was collected under flooding and during the post-flooding recovery period. A total of 498 and 70 proteins were significantly changed in control and post-flooding recovering soybeans, respectively. Based on proteomic and clustering analyses, three proteins were selected for mRNA expression and enzyme activity assays. Pyruvate kinase was increased under flooding, but gradually decreased during post-flooding recovery period at protein abundance, mRNA, and enzyme activity levels. Nucleotidylyl transferase was decreased under flooding and increased during post-flooding recovery at both mRNA expression and enzyme activity levels. Beta-ketoacyl reductase 1 was increased under flooding and decreased during recovery at protein abundance and mRNA expression levels, but its enzyme activity gradually increased during the post-flooding recovery period. These results suggest that pyruvate kinase, nucleotidylyl transferase, and beta-ketoacyl reductase play key roles in post-flooding recovery in soybean hypocotyl by promoting glycolysis for the generation of ATP and regulation of secondary metabolic pathways. Biological significance This study analyzed post-flooding recovery response mechanisms in soybean hypocotyl, which is a model organ for studying secondary growth, using a gel-free proteomic technique. Mass spectrometry analysis of proteins extracted from soybean hypocotyls identified 20 common proteins between control and flooding-stressed soybeans that changed significantly in abundance over time. The hypocotyl proteins that changed during post-flooding recovery were assigned to protein, development, secondary metabolism, and glycolysis categories. The analysis revealed that three proteins, pyruvate kinase, nucleotidylyl transferase, and beta-ketoacyl reductase, were increased in hypocotyl under flooding conditions and during post-flooding recovery. The proteins are involved in glycolysis, nucleotide synthesis and amino acid activation, and complex fatty acid biosynthesis. [ABSTRACT FROM AUTHOR]

Eight cultivars of Brassica oleracea var. capitata and two types of explant (hypocotyl and cotyledon) were tested for their potential to regenerate under in vitro conditions. Hypocotyl and cotyledon explants from 10-d-old seedlings were subcultured onto different callus induction media based on Murashige and Skoog (MS) basal medium supplemented with 1% sucrose and different concentrations and combinations of plant growth regulators. Hypocotyl explants were found to be more suitable for callus induction and organogenesis than cotyledon explants for all cultivars tested. In terms of regeneration, the cv. 'Amager' was significantly more responsive than the other cultivars tested and produced the highest number of shoots/buds per explant. Moreover, among five types of media tested, MS + 8.88 μM 6-benzyloaminopurine (BAP) + 0.53 μM α-naphthylacetic acid (NAA) was most effective for shoot regeneration. Rooting was achieved within 10-15 d on all the rooting media, but MS medium containing 5.37 μM NAA produced the maximum number of strong and healthy roots. Plantlets (95%) were subsequently established in the greenhouse, and no phenotypic variations were observed among regenerated plants. This plant regeneration protocol could be suitable for a wide range of cabbage cultivars. [ABSTRACT FROM AUTHOR]

Sweet Basil (Ocimum basilicum L.) is most important medicinal and aromatic plant used in aromatherapy, cosmetics, perfume and food products in fresh or dried form. The present study provides a reliable and reaptable in vitro plant regeneration protocol of cultivated sweet basil of Turkey. Basil seeds were surface sterilized with 2.5% NaOCl. Epicotyl, hypocotyl and shoot tip explants were isolated from 12-14 days old in vitro grown seedlings. The explants were cultured on MS medium containing 0.80-2.40 mg/L TDZ with or without 0.10 mg/L IBA alongwith 1.0 mg/L PVP and 3.0 g/L activated charcoal. Cent percent callus induction were recorded on all explants on all culture mediums. Shoot regeneration frequency of epicotyl, hypocotyl and shoot tip explant ranged 75.0-100, 25.0-83.33 and 66.67-100% respectively. Maximum number of shoots from epicotyl (3.22) and shoot tip (3.58) were scored on MS medium containing 2.40 mg/l TDZ-0.10 mg/l IBA. Whereas, hypocotyl explant induced maximum number of (5.17) shoots per explant on MS medium with 2.0 mg/l TDZ. Relatively shorter roots of less than 1.0 cm were recorded irrespective of explant type or culture medium. However, shoots were successfully rooted and plantlets were transferred to pots and acclimatized well in growth room conditions. [ABSTRACT FROM AUTHOR]

Gravitropism and phototropism of the primary inflorescence stems were examined in a dominant Aux/IAA mutant of Arabidopsis, axr2/iaa7, which did not display either tropism in hypocotyls. axr2- 1 stems completely lacked gravitropism in the dark but slowly regained it in light condition. Though wild-type stems showed positive phototropism, axr2 stems displayed negative phototropism with essentially the same light fluence-response curve as the wild type (WT). Application of 1-naphthaleneacetic acid-containing lanolin to the stem tips enhanced the positive phototropism of WT, and reduced the negative phototropism of axr2. Decapitation of stems caused a small negative phototropism in WT, but did not affect the negative phototropism of axr2. p-glycoprotein 1 ( pgp1) pgp19 double mutants showed no phototropism, while decapitated double mutants exhibited negative phototropism. Expression of auxin-responsive IAA14/SLR, IAA19/MSG2 and SAUR50 genes was reduced in axr2 and pgp1 pgp19 stems relative to that of WT. These suggest that the phototropic response of stem is proportional to the auxin supply from the shoot apex, and that negative phototropism may be a basal response to unilateral blue-light irradiation when the levels of auxin or auxin signaling are reduced to the minimal level in the primary stems. In contrast, all of these treatments reduced or did not affect gravitropism in wild-type or axr2 stems. Tropic responses of the transgenic lines that expressed axr2-1 protein by the endodermis-specific promoter suggest that AXR2-dependent auxin response in the endodermis plays a more crucial role in gravitropism than in phototropism in stems but no significant roles in either tropism in hypocotyls. [ABSTRACT FROM AUTHOR]

We addressed the question of whether an additional round of endoreduplication in dark-grown hypocotyls is a common feature in dicotyledonous plants having endopolyploid tissues. Ploidy distributions of hypocotyl tissues derived from in vitro-grown spinach (Spinacia oleracea L. cv. Atlas) seedlings grown under different light conditions were analyzed by flow cytometry. An additional round of endoreduplication (represented by 32C cells) was found in the dark-grown hypocotyl tissues. This response was inhibited by light, the intensity of which is a crucial factor for the inhibition of endoreduplication. The higher ploidy cells in cortical tissues of the dark-grown hypocotyls had larger cell sizes, suggesting that the additional round of endoreduplication contributes to hypocotyl elongation. More importantly, a polar auxin transport inhibitor, 2,3,5-triiodobenzoic acid (TIBA), strongly inhibits endoreduplication, not only in spinach but also in Arabidopsis. Because other polar auxin transport inhibitors or an auxin antagonist show no or mild effects, TIBA may have a specific feature that inhibits endoreduplication. [ABSTRACT FROM AUTHOR]

The aim of the study was to determine the effect of the mammalian female sex hormone estrone on differentiation of somatic tissues and on induction of autonomous endosperm in culture of female gametophyte cells of Arabidopsis thaliana ecotype Columbia (Col-0). In culture, estrone-stimulated development of autonomous endosperm (AE) occurred in 14.7% of unpollinated pistils. The AE represented development stages similar to those of young endosperm after fertilization and AE of fis mutants in vivo. In the majority of ovules the AE was in a few-nucleate young stage. Some ovules showed more advanced stages of AE development, with nuclei and cytoplasm forming characteristic nuclear cytoplasmic domains (NCDs). Sporadically, AE was divided into regions characteristic for Arabidopsis endosperm formed after fertilization. Direct organogenesis (caulogenesis, rhizogenesis), callus proliferation and formation of trichome-like structures were observed during in vitro culture of hypocotyls and cotyledons of 3-day-old seedlings cultured on medium supplemented with estrone for 28 days. Histological analysis showed adventitious root formation and changes in explant anatomy caused by estrone. [ABSTRACT FROM AUTHOR]

* Premise of the study: Adventitious root (AR) formation is indispensable for vegetative propagation, but difficult to achieve in many crops. Understanding its molecular mechanisms is thus important for such species. Here we aimed at developing a rooting protocol for direct AR formation in stems, locating cellular AR origins in stems and exploring molecular differences underlying adventitious rooting in hypocotyls and stems. * Methods." In-vitro-grown hypocotyls or stems of wild-type and transgenic ecotype Columbia (Col-0) of Arabidopsis thaliana were rooted on rooting media. Anatomy of AR formation, qRT-PCR of some rooting-related genes and in situ GUS expression were carried out during rooting from hypocotyls and stems. * Key results: We developed a rooting protocol for AR formation in stems and traced back root origins in stems by anatomical and in situ expression studies. Unlike rooting in hypocotyls, rooting in sterns was slower, and AR origins were mainly from lateral parenchyma of vascular bundles and neighboring starch sheath cells as well as, to a lesser extent, from phloem cap and xylem parenchyma. Transcript levels of GH3-3, LBD16, LBD29, and LRP1 in hypocotyls and stems were similar, but transcript accumulation was delayed in stems. In situ expression signals of DRS::GUS, LBD16::GUS, LBD29::GUS, and rolB::GUS reporters in stems mainly occurred at the root initiation sites, suggesting their involvement in AR formation. * Conclusions: We have developed an efficient rooting protocol using half-strength Lepoivre medium for studying AR formation in stems, traced back the cellular AR origins in stems, and correlated expression of roofing-related genes with root initiation sites. [ABSTRACT FROM AUTHOR]

Cytokinins ( CKs) and glucose ( GLC) control a number of common responses in plants. We hypothesize that there may be an extensive overlap between CK- and GLC-signalling pathways. Microarray along with physiological analysis has been performed to find out the interdependence/overlap between CK and GLC signal transduction pathways in Arabidopsis seedlings. GLC could transcriptionally affect 76% of CK-regulated genes at whole genome level, 89% of which are agonistically regulated. GLC may also affect CK-regulated gene expression via non-transcriptional pathways. GLC can regulate several genes involved in CK metabolism and signalling. A number of gene families involved in development and stress are commonly regulated by CK and GLC. Physiologically, both GLC and CK could regulate hypocotyl length in dark. GLC and CK signalling may integrate at the level of type A Arabidopsis response regulators ( ARRs) in controlling hypocotyl length. Both GLC and CK signalling cannot alter hypocotyl length in dark in auxin-signalling mutants AUXIN RESPONSE2 / INDOLE-3- ACETIC ACID7 ( AXR2/IAA7) and AXR3/IAA17 suggesting that they may involve auxin-signalling component as a nodal point. Here, we demonstrate that there is an extensive overlap between CK- and GLC-regulated gene expression and physiological responses. [ABSTRACT FROM AUTHOR]

Background Aerial plant surfaces are covered by a lipophilic cuticular membrane ( CM) that restricts the transport of water and small solutes. Non-aerial tissues do not exhibit such a barrier. Recent data have shown that large relative to CM hydrophilic agrochemicals were able to pass at high rates through the non-aerial coleoptile. Results A moderately large hydrophilic solute like PEG 1000 with a mean molar volume of 782 cm3 mol−1 was rejected by the non-aerial hypocotyl. Uptake of smaller solutes like urea (46.5 cm3 mol−1) was fast and with 99% after 1 day. Cut-off size estimations suggest a pore size diameter below 1.5 nm. Conclusion Aerial and non-aerial CM differ largely in their absolute barrier properties. This difference is related to the absence of embedded cuticular waxes in the non-aerial hypocotyl membrane, which make the CM physically dense and cause low solubility of hydrophilic solutes. The free volume for diffusion at the interface of the non-aerial hypocotyl cuticle to the environment is much larger resulting in higher penetration rates. It is suggested that diffusion through the non-aerial hypocotyl does not proceed in a real channel system with continuous aqueous phase but is more like transport through a filter with restricted diffusion in the pore openings. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Planting depth can cause nonuniform emergence and poor field stands. There have been no investigations to compare the planting depth on field emergence between vegetable soybean and grain soybean [Glycine max (L.) Merr.]. This study examined the effect of planting depth on preemergence and seedling emergence in growth chamber conditions using one vegetable soybean and one grain soybean cultivar. The hypocotyl and radicle length in the vegetable soybean were significantly longer than that of the grain soybean at emergence, while the hypocotyl and radicle diameter in the vegetable soybean were significantly larger than that of the grain soybean during emergence period irrespective of planting depth. The weight of hypocotyl + radicle in the vegetable soybean was significantly greater than that of the grain soybean during emergence period irrespective of planting depth and days after planting, but deeper planting depth reduced cotyledon weight in the vegetable soybean strongly at emergence. As planting depth increased from shallow (1-cm) to deep (5-cm), emergence declined. However, the grain soybean seed consistently emerged better than the vegetable soybean seed. Emergence of both the grain soybean seed and the vegetable soybean was >65% until planting depth increased to 3-cm, while the vegetable soybean seed had the lowest emergence (<30%) at the deepest (5-cm) level. The 3-cm planting depth had no effect on the emergence of both the grain soybean and the vegetable soybean. The vegetable soybean was more susceptible to deeper planting depth than the grain soybean. [ABSTRACT FROM AUTHOR]

Background and Aims How plant cell-cycle genes interface with development is unclear. Preliminary evidence from our laboratory suggested that over-expression of the cell cycle checkpoint gene, WEE1, repressed growth and development. Here the hypothesis is tested that the level of WEE1 has a dosage effect on growth and development in Arabidospis thaliana. To do this, a comparison was made of the development of gain- and loss-of-function WEE1 arabidopsis lines both in vivo and in vitro. Methods Hypocotyl explants from an over-expressing Arath;WEE1 line (WEE1oe), two T-DNA insertion lines (wee1-1 and wee1-4) and wild type (WT) were cultured on two-way combinations of kinetin and naphthyl acetic acid. Root growth and meristematic cell size were also examined. Key Results Quantitative data indicated a repressive effect in WEE1oe and a significant increase in morphogenetic capacity in the two T-DNA insertion lines compared with WT. Compared with WT, WEE1oe seedlings exhibited a slower cell-doubling time in the root apical meristem and a shortened primary root, with fewer laterals, whereas there were no consistent differences in the insertion lines compared with WT. However, significantly fewer adventitious roots were recorded for WEE1oe and significantly more for the insertion mutant wee1-1. Compared with WT there was a significant increase in meristem cell size in WEE1oe for all three ground tissues but for wee1-1 only cortical cell size was reduced. Conclusions There is a gene dosage effect of WEE1 on morphogenesis from hypocotyls both in vitro and in vivo. [ABSTRACT FROM AUTHOR]

Euphorbia geniculata, an annual weed of arable land native to America and invasive in subtropical and tropical regions, is able to regenerate from seeds and is also able to produce adventitious buds on the hypocotyl. Whether sprouting from adventitious buds represents a mechanism for surviving severe injury, and whether this ability is crucial for species invasion is, however, not known. The significance of such sprouting was investigated with a field survey and a pot experiment. Among 897 plants in 25 field populations surveyed in Indonesia, only a few exhibited marks of injury and sprouting from adventitious buds. When seeds were collected from 12 of the populations and used in a pot experiment, however, the seedlings were able to survive severe injury (removal of all tissue above the hypocotyl) by sprouting from adventitious buds on the hypocotyl and were able to set seed, although they produced less vegetative and generative (flowers and fruits) biomass than control plants. Growth but not fitness of plants in the pot experiment was population specific but neither growth characteristic correlated with disturbance level assessed in the field. Although the pot experiment indicates that E. geniculata can cope with severe injury by adventitious sprouting from the hypocotyl, the survey data are inconsistent with the hypothesis that such adventitious sprouting is important for the plant's invasion in tropical regions. [ABSTRACT FROM AUTHOR]

Development of a suitable genetic transformation system is the backbone of transgenic technology for efficient recovery of Jatropha curcas plants with desirable traits. Although in vitro plant regeneration protocols for shoot tip, leaf, and hypocotyl explants of J. curcas have been reported, these protocol have not been translated into efficient genetic transformation systems. The objective of this study was to standardize the parameters influencing transient β-glucuronidase reporter gene expression following Agrobacterium-mediated genetic transformation using shoot tip, leaf, and hypocotyl explants of Jatropha curcas. Disarmed Agrobacterium tumefaciens strain EHA105, harboring pCAMBIA2301 carrying neomycin phosphotransferase (nptII) as a selectable marker and the β-glucuronidase (GUS) as a reporter gene, were used for transformation. Frequencies of GUS gene expression of 86.7%, 78.3%, and 74.2% were obtained for leaf, hypocotyls, and shoot tip explants, respectively. The transgenic nature of the kanamycin-resistant explants was also confirmed by using polymerase chain reaction (PCR) assay. Because, to date, there is no report on Agrobacterium-mediated transformation of shoot tip, leaf, and hypocotyl explants of Jatropha curcas, our findings/protocol should be useful for recovering stable transgenic Jatropha curcas plants from these explants. [ABSTRACT FROM PUBLISHER]

Auxin regulates plant growth and development in part by activating gene expression. Arabidopsis thaliana SMALL AUXIN UP RNAs ( SAURs) are a family of early auxin-responsive genes with unknown functionality. Here, we show that transgenic plant lines expressing artificial microRNA constructs ( aMIR-SAUR-A or - B) that target a SAUR subfamily ( SAUR61-SAUR68 and SAUR75) had slightly reduced hypocotyl and stamen filament elongation. In contrast, transgenic plants expressing SAUR63:GFP or SAUR63:GUS fusions had long hypocotyls, petals and stamen filaments, suggesting that these protein fusions caused a gain of function. SAUR63:GFP and SAUR63:GUS seedlings also accumulated a higher level of basipetally transported auxin in the hypocotyl than did wild-type seedlings, and had wavy hypocotyls and twisted inflorescence stems. Mutations in auxin efflux carriers could partially suppress some SAUR63:GUS phenotypes. In contrast, SAUR63:HA plants had wild-type elongation and auxin transport. SAUR63:GFP protein had a longer half-life than SAUR63:HA. Fluorescence imaging and microsomal fractionation studies revealed that SAUR63:GFP was localized mainly in the plasma membrane, whereas SAUR63:HA was present in both soluble and membrane fractions. Low light conditions increased SAUR63:HA protein turnover rate. These results indicate that membrane-associated Arabidopsis SAUR63 promotes auxin-stimulated organ elongation. [ABSTRACT FROM AUTHOR]

Circadian regulated changes in growth rates have been observed in numerous plants as well as in unicellular and multicellular algae. The circadian clock regulates a multitude of factors that affect growth in plants, such as water and carbon availability and light and hormone signalling pathways. The combination of high-resolution growth rate analyses with mutant and biochemical analysis is helping us elucidate the time-dependent interactions between these factors and discover the molecular mechanisms involved. At the molecular level, growth in plants is modulated through a complex regulatory network, in which the circadian clock acts at multiple levels. [ABSTRACT FROM AUTHOR]

Ten accessions belonging to the Brassica oleracea subspecies alba and rubra, and to B. oleracea var. sabauda were used in this study. Protoplasts were isolated from leaves and hypocotyls of in vitro grown plants. The influence of selected factors on the yield, viability, and mitotic activity of protoplasts immobilized in calcium alginate layers was investigated. The efficiency of protoplast isolation from hypocotyls was lower (0.7 ± 0.1 × 10 ml) than for protoplasts isolated from leaf mesophyll tissue (2 ± 0.1 × 10 ml). High (70-90%) viabilities of immobilized protoplasts were recorded, independent of the explant sources. The highest proportion of protoplasts undergoing divisions was noted for cv. Reball F1, both from mesophyll (29.8 ± 2.2%) and hypocotyl (17.5 ± 0.3%) tissues. Developed colonies of callus tissue were subjected to regeneration and as a result plants from six accessions were obtained. [ABSTRACT FROM AUTHOR]

This study was carried out to assess the potential of hypocotyl explants for multiple-propagation by intensive sweetener variety with high yielding in stevia of self-fertilization. Agronomical character of self-fertilization shown a height range 72.0~ 120.7 cm, branch's 4.9~56.6 in stevia. Selection of high content of Rebaudioside A (RA) from segregating population in mixing variety have a variety, 'DA1' (55.2%) from HPLC analysis. On a developing of multiple-propagation in stevia, hypocotyl explants used to select for reasonable medium under the influence of each plant growth regulators concentrations. In a Mix treatment of plant growth regulators, as Murashige and Skoog medium with 1.5 mg/L BA and 0.5 mg/L Kinetin showed the most favorable. We got the multiple-propagation of 30 shoots from one inoculated hypocotyl explants as the result of these bases. Rooting induced superbly on MS medium with 0.1 mg/L IBA with inoculated shoots. All of the rooting plants were adapted to a normal seedling. This method of multi-propagation is used effectively in Rebaudioside A productivity elevation. [ABSTRACT FROM AUTHOR]

The photoperiodic response is one of the adaptation mechanisms to seasonal changes of lengths of day and night. The circadian clock plays pivotal roles in this process. In Arabidopsis, LHY, CCA1, ELF3, and other clock proteins play major roles in maintaining circadian rhythms. lhy;cca1 double mutants with severe defects in circadian rhythms showed accelerated flowering under short days (SDs), but delayed flowering under continuous light (LL). The protein level of the floral repressor SVP increased in lhy;cca1 mutants under LL, and the late-flowering phenotype of lhy;cca1 mutants was partially suppressed by svp, flc, or elf3. ELF3 interacted with both CCA1 and SVP, and elf3 suppressed the SVP accumulation in lhy;cca1 under LL. These results suggest that the unique mechanism of the inversion of the flowering response of lhy;cca1 under LL may involve both the ELF3–SVP/FLC-dependent and -independent pathways. In this work, elf3-1 seeds were mutagenized with heavy-ion beams and used to identify mutation(s) that delayed flowering under LL but not long days (LDs) or SDs even without ELF3. In this screening, seven candidate lines named suppressor of elf3 1 (self1), sel3, sel5, sel7, sel14, sel15, and sel20 were identified. Genetic analysis indicated that sel20 was a new deletion allele of a mutation in the blue light receptor, CRY2. A late-flowering phenotype and decrease of FT expression in the elf3;sel20 double mutant was obvious under LL but not under SDs or LDs. These results indicated that the late-flowering phenotype in the double mutant elf3;sel20 as well as in lhy;cca1 was affected by the presence of darkness. The results suggest that CRY2 may play more essential roles in the acceleration of flowering under LL than LDs or SDs. [ABSTRACT FROM PUBLISHER]

Seeds of soybeans and mung beans were soaked into five different concentrations (0, 0. 05, 0.10, 0. 20, 0. 30 mg/L) of natural brassinolide (NBR) solution. According to the results, natural brassinolide treatment could improve seed germination rate ad hypocotyl-radicle ratio of soybeans and mung beans and promote the growth of sprouts. To be specific, seed germination rate of soybeans reached the highest in 0. 05 mg/L natural brassinolide treatment, which was improved by 25.0 percentage points compared with the control group, and the sprout length was improved by 4. 33 cm; 0.30 mg/L natural brassinolide exhibited the most significant promotion effect on seed germination and sprout growth of mung beans, seed germination rate was improved by 18.3 percentage points and sprout length was improved by 7.29 cm; hypocotyl-radicle ratio of soybean and mung be a sprouts reached the highest (2.96, 1.43) in 0.05 mg/L natural brassinolide treatment. [ABSTRACT FROM AUTHOR]

Al inhibits root elongation at micromolar concentrations, but the mechanisms leading to this process are unknown. In these studies, Al-induced inhibition of cell elongation was examined using hypocotyl of okra (Abelmoschus esculentus Moench cv. Clemson Spineless) as an experimental model. One-h exposure to Al (0.5 mM A1Cl3) in the presence of 10 μM auxin in 0.5 mM CaCl2, pH 4.0 significantly inhibited auxin-induced cell elongation of okra hypocotyl segments. Elongation was further suppressed with increasing Al concentrations up to 1 mM. Treatment of the hypocotyl with 1 mM citrate for 10 minutes after 2-h exposure to Al resulted in significant recovery of elongation. The amount of Al in the cell wall relative to the total in the tissue was 96.0, 96.2, and 85.4%, respectively, following 1-, 2-, and 3-h exposure to the Al solution. The total and cell wall Al content was decreased by half after the citrate desorption treatment. Further-more, 95% of Al was found in the epidermis, and 95% of the Al in the epidermis was associated with the cell wall. Experiments using split hypocotyl segments showed that Al exposure increased the outward bending of hypocotyl segments, suggesting that the epidermis elongation was specifically inhibited by Al. Al inhibited the autolysis of epidermis by about 20%, but had little effect on the autolysis of core tissue. Taken together, these results suggest that Al binding in the epidermal cell wall inhibits critical components in cell wall loosening mechanism, resulting in inhibition of cell elongation. [ABSTRACT FROM AUTHOR]