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At least 775 records · Page 43Linked to original sources

PubMed2000

Reversion of flowering in Glycine Max (Fabaceae).

Photoperiodic changes, if occurring before a commitment to flowering is established, can alter the morphological pattern of plant development. In this study, Glycine max (L.) Merrill cv. Ransom plants were initially grown under an inductive short-day (SD) photoperiod to promote flower evocation and then transferred to a long-day (LD) photoperiod to delay flower development by reestablishing vegetative growth (SD-LD plants). Some plants were transferred back to SD after 4-LD exposures to repromote flowering (SD-LD-SD plants). Alterations in organ initiation patterns, from floral to vegetative and back to floral, are characteristic of a reversion phenomenon. Morphological features that occurred at the shoot apical meristem in SD, LD, SD-LD, and SD-LD-SD plants were observed using scanning electron microscopy (SEM). Reverted plants initiated floral bracts and resumed initiation of trifoliolate leaves in the two-fifths floral phyllotaxy prior to terminal inflorescence development. When these plants matured, leaf-bract intermediates were positioned on the main stem instead of trifoliolate leaves. Plants transferred back to a SD photoperiod flowered earlier than those left in LD conditions. Results indicated that in plants transferred between SDs and LDs, photoperiod can influence organ initiation in florally evoked, but not committed, G. max plants.

Journal Article↗

PubMed1993

CLAVATA1, a regulator of meristem and flower development in Arabidopsis.

We have investigated the effects on plant development of mutations in the Arabidopsis thaliana CLAVATA1 gene. In clavata1 plants, vegetative, inflorescence and floral meristems are all enlarged relative to wild type. The apical meristem can fasciate in the more severe mutant alleles, and this fasciation can occur prior to the transition to flowering. Flowers of clavata1 plants can have increased numbers of organs in all four whorls, and can also have additional whorls not present in wild-type flowers. Double mutant combinations of clavata1 with agamous, apetala2, apetala3 and pistillata indicate that CLAVATA1 controls the underlying floral meristem structure upon which these homeotic genes act. Double mutant combinations of clavata1 with apetala1 and leafy indicate CLAVATA1 plays a role in establishing and maintaining floral meristem identity, in addition to its role in controlling meristem size. In support of this, RNA expression patterns of AGAMOUS and APETALA1 are altered in clavata1 flowers.

Arabidopsis↗

PubMed2005

Molecular characterization of ONAC300, a novel NAC gene specifically expressed at early stages in various developing tissues of rice.

Members of the plant-specific gene family referred to as the NAC family (for NAM-ATAF-CUC-related) are involved in various functions including the regulation of plant development. However, no detailed molecular characterization of any member of the NAC family has yet been reported from monocots. Here, we report such a characterization of ONAC300, a novel NAC-family gene identified using a cDNA cloned from microdissected phloem cells of rice. The predicted ONAC300 protein sequence falls into the NAM subgroup, which also contains the proteins CUC1 and CUC2 from Arabidopsis, CUP from snapdragon, CmNACP from pumpkin and NAM from petunia. High levels of ONAC300 mRNA were detected by in situ hybridization in developing shoot apical meristem (SAM) and in the associated young leaves. The use of an ONAC300:: GUS reporter gene revealed that the ONAC300 promoter was expressed predominantly in developing vascular tissues of the leaves and roots. The construct was also expressed in anther filaments, rachis and carpel styles. RT-PCR analysis further revealed that the levels of ONAC300 transcripts were higher in leaves, roots and culms than in panicles. The observed expression pattern of ONAC300 is quite different from those of the dicot NAC genes previously reported. Thus, ONAC300 is a novel member of the NAC family which is expressed at very early developmental stages in the shoot, root and flower, as well as in the mature phloem of vascular tissues in rice.

Amino Acid Sequence↗

PubMed2006

Autophagy in the control of programmed cell death.

Programmed cell death (PCD) is essential for plant development and immunity. Localized PCD is associated with the hypersensitive response (HR), which is a constituent of a successful plant innate immune response. Plants have developed mechanisms to meticulously prevent HR-PCD lesions from spreading. Our understanding of these mechanisms is still in its incipient stages. A recent study demonstrated that autophagy, a universally conserved process of macromolecule turnover, plays a pivotal role in controlling HR-PCD. The molecular identity of the mediators between the PCD and HR pathways is still obscure, but recent work has begun to shed light on the relationship between HR-PCD and autophagy and to suggest possible mechanisms for the regulation of these pathways.

Apoptosis↗

PubMed2002

[Agroinfiltration, a useful technique in plant molecular biology research].

Agroinfiltration is a newly developed plant transient gene expression technique, which is simple, rapid and reproducible. It has been widely used in analyses of foreign gene expression, hypersensitive reaction, gene silencing, promoter activity and identification of new disease-resistance genes. In this paper, we describe the principle and the operation procedure of Agroinfiltration and its application in diverse aspects of plant molecular biology research. Our experiences in modification of the Agroinfiltration technique are also provided.

Agrobacterium tumefaciens↗

PubMed2005

Within-plant variation in induced defence in developing leaves of cotton plants.

According to optimal defence theory (ODT) plants should invest in stronger defence in the most valuable parts, such as reproductive or young tissue. Cotton plants are known to express high resistance to herbivore feeding in the developing leaves at the top of the plant after herbivore-damage. Cotton plants also have developing leaves on side shoots from the nodes all along the plant. This allowed us to investigate within-plant distribution of defence between younger tissues at different locations on the plant. We found that all developing leaves showed increased resistance to feeding by larvae of the generalist moth Spodoptera littoralis after herbivore damage to leaves of the plant. An increase in the concentration of secondary compounds, terpenoid aldehydes, was found in developing leaves both at the top of the plant and on the side shoots. However, the resistance was stronger in the top leaves than in the side shoot leaves, showing that there is intra-plant variation in the induced response between different leaves of the same age. After the initial damage, larval feeding mainly occurred on the older, fully developed true leaves. Furthermore, the herbivore-induced resistance in the developing leaves reduced upward movement of feeding larvae on the plant and reduced the feeding on the upper parts of the plant over a period of at least 6 days. The plant thus benefits from defending all developing leaves by directing feeding to older, less valuable leaves and lower parts of the plant. The observed distribution of defence within cotton plants supports ODT.

Age Factors↗

PubMed1995

Effect of lopping on water potential, transpiration, regrowth, (14)C-photosynthate distribution and biomass production in Alnus glutinosa.

The effects of light, moderate and heavy branch pruning or lopping treatments (resulting in removal of 28-31, 56-60 and 80-82% of the foliage, respectively, unlopped control = 0%) were studied in 3-year-old black alder (Alnus glutinosa L. Gaertn.) plants. Within 24 h of lopping, transpiration rates decreased and water potentials increased. The effects of lopping continued for 48 days. The improved water status of the lopped plants enhanced water-use efficiency during the first 30 days. Regrowth was related to a combination of enhanced net assimilation rates during the first 30 days after lopping, use of current photoassimilates and stored carbohydrates in the roots (particularly in medium and heavily lopped plants) for the production of new leaf area, and delayed leaf senescence. The lightly and moderately lopped plants developed 62 and 57% more leaf area, respectively, than the unlopped plants, but total leaf area development was slower in the heavily lopped plants. Lightly lopped plants produced total biomass equivalent to that of unlopped plants, but the moderately and heavily lopped plants produced less biomass than the unlopped plants. During the first 30 days after lopping, there was a net loss of nodule dry matter and recovery to control values did not occur during the period of study. Immediately (24 h) after lopping, more (14)C-photosynthate was translocated to the roots of lopped plants than to the roots of unlopped plants. When a branch near the base of the main stem was fed (14)CO(2), (14)C-photosynthate translocation to the shoot increased with increasing intensity of lopping, at 50 days after lopping.

Journal Article↗

PubMed1991

Embryogenic plant cells in microgravity.

Plant development entails an orderly progression of cellular events both in terms of time and geometry. There is circumstantial evidence that in the controlled environment of the higher plant embryo sac gravity (g) may play a role in shaping embryo development. It follows that normal embryo development may not occur reliably and efficiently under the weak microgravity environment of space. More attention must be given to studying the many aspects of reproductive biology in the space environment in order to be confident that higher plants will not only survive, but produce large numbers of viable embryos in a "seed to seed to seed" type experiment. Until the time arrives when successive generations of flowering plants can routinely be grown and intensively studied, the best we can do is to utilize acceptable surrogate systems and begin, piece-meal, to accumulate information on important aspects of plant reproduction in microgravity. Cultured cells can play an important role in these activities since they can be grown to be morphogenetically competent and can be evaluated as to their ability to simulate embryogenic events usually identified with fertilized eggs in the embryo sac of the ovule in the ovary. Cultured cells can also be manipulated with relative ease. The extreme plasticity of such demonstrably totipotent cell systems provides a means to test environmental effects such as microgravity on a potentially "free-running" entity without the constraints or confines of an embryo sac. The successful manipulation and management of plant cells and propagules in space also has significance for exploitation of biotechnologies in microgravity since embryogenic systems, perforce, are an important component of plant genetic engineering manipulations.

Cell Division↗

PubMed2003

Expression of subtilisin-like serine proteases in Arabidopsis thaliana is cell-specific and responds to jasmonic acid and heavy metals with developmental differences.

The expression of two novel subtilisin-like serine proteases At-SLP2 and At-SLP3 from Arabidopsis thaliana and the recently identified Arabidopsis subtilase ARA12 was analysed with respect to plant development, stress response and cell specificity. In juvenile plants the mRNAs of the subtilisin-like proteases At-SLP2, At-SLP3 and ARA12 were detected with varying transcript levels in leaves but not in roots. In mature Arabidopsis plants transcripts were abundant in leaves, roots and flowers revealing developmental regulation of synthesis of subtilases. By in situ hybridization it was shown that the subtilisin-like proteases were predominantly present in epidermal cells and in the vascular bundles, in the phloem and in developing xylem elements. In flowers additional signals were localized, for example, in pistils, ovules and anthers. In flowers and juvenile developing leaves, expression of the subtilisin-like proteases increased following treatment with jasmonate and cadmium, respectively, suggesting that these proteases are responsive to stress and pathogen stimuli. The physiological relevance of these data in relation to plant morphogenesis and development is discussed.

Journal Article↗

PubMed1997

PLANT IN VITRO TRANSCRIPTION SYSTEMS.

In vitro transcription systems provide a powerful tool for detailed analysis of transcription reactions including initiation, elongation, and termination. Despite problems inherent to plant cells, efforts have been made to develop plant in vitro transcription systems in the past decade. These efforts have finally culminated in the development of reliable in vitro systems from suspension-cell cultures of both monocot and dicot plants. These systems can be useful in elucidating the specific mechanisms involved in the process of plant transcription and thus can potentially open a new era of transcription studies in plants.

Journal Article↗

PubMed2006

The gene responsible for borate cross-linking of pectin Rhamnogalacturonan-II is required for plant reproductive tissue development and fertilization.

Deficiencies in boron, a microelement that is essential for the growth and development of higher plants, often cause problems in reproductive growth. Rhamnogalacturonan-II (RG-II) in cell wall pectin acts as the sole receptor for boron in plant cells, forming a borate cross-linked RG-II dimer (dRG-II-B), but the physiological functions of dRG-II-B remain unknown. We have previously shown that the pectin glucuronyltransferase 1 gene NpGUT1, which is involved in the biosynthesis of RG-II sugar chains, is essential for the formation of the RG-II-B complex, resulting in tight intercellular attachment in meristematic tissues. Because NpGUT1 expression was found to be abundant in reproductive organs in addition to meristematic tissues, we analyzed the expression and functions of NpGUT1 in more detail in tobacco reproductive tissues. Specific NpGUT1 expression was detected in the tapetum of flower buds and in the pollen, pollen tube tips, and transmitting tissue of the pistils of flowers. Dexamethasone-induced expression of the NpGUT1 antisense gene in flower buds resulted in the formation of sterile flowers with aberrant development of pollen and transmitting tissue. Pollen tubes could not pass through pistils with aborted transmitting tissue, and expression of an NpGUT1 antisense gene in germinating pollen inhibited pollen tube elongation, accompanied by the absence of pectin RG-II and boron in the pollen tube tip. These results indicate that expression of NpGUT1 is required for the development and functions of male and female tissues.

Borates↗

PubMed2005

Involvement of ethylene and 1-aminocyclopropane-1-carboxylate synthase gene in regulation of programmed cell death during rose (Rosa x hybrida) flower development.

Programmed cell death (PCD) is an integral part of plant development. Flower petal usually has the shortest lifetime among all plant organs. There must be a sensitive, tightly controlled PCD in the life cycle of the flower. To understand its mechanism, the ethylene production rate of petals and its correlation with degree of senescence, 1-aminocyclopropane-1-carboxylate (ACC) synthase gene expression, ACC synthase activity and ACC content were determined through the whole flower development period which was arbitrarily divided into five stages depending on appearance of the flower. The results showed that ethylene was not detectable at stages 1 and 2, appeared at stage 3 and increased at stage 5. Transcript of ACC synthase gene did not accumulate at stages 1 and 2, but did so at stages 3-5, and increased gradually at stage 5. ACC synthase activity and ACC content changed in similar way to ethylene production. Ethylene plays a critical role in initiation of rose flower senescence through regulating petal PCD.

Apoptosis↗

PubMed2003

crinkle, a novel symbiotic mutant that affects the infection thread growth and alters the root hair, trichome, and seed development in Lotus japonicus.

To elucidate the mechanisms involved in Rhizobium-legume symbiosis, we examined a novel symbiotic mutant, crinkle (Ljsym79), from the model legume Lotus japonicus. On nitrogen-starved medium, crinkle mutants inoculated with the symbiont bacterium Mesorhizobium loti MAFF 303099 showed severe nitrogen deficiency symptoms. This mutant was characterized by the production of many bumps and small, white, uninfected nodule-like structures. Few nodules were pale-pink and irregularly shaped with nitrogen-fixing bacteroids and expressing leghemoglobin mRNA. Morphological analysis of infected roots showed that nodulation in crinkle mutants is blocked at the stage of the infection process. Confocal microscopy and histological examination of crinkle nodules revealed that infection threads were arrested upon penetrating the epidermal cells. Starch accumulation in uninfected cells and undeveloped vascular bundles were also noted in crinkle nodules. Results suggest that the Crinkle gene controls the infection process that is crucial during the early stage of nodule organogenesis. Aside from the symbiotic phenotypes, crinkle mutants also developed morphological alterations, such as crinkly or wavy trichomes, short seedpods with aborted embryos, and swollen root hairs. crinkle is therefore required for symbiotic nodule development and for other aspects of plant development.

Cell Surface Extensions↗

PubMed2005

Functional redundancy of PIN proteins is accompanied by auxin-dependent cross-regulation of PIN expression.

Plant development displays an exceptional plasticity and adaptability that involves the dynamic, asymmetric distribution of the phytohormone auxin. Polar auxin flow, which requires polarly localized transport facilitators of the PIN family, largely contributes to the establishment and maintenance of the auxin gradients. Functionally overlapping action of PIN proteins mediates multiple developmental processes, including embryo formation, organ development and tropisms. Here we show that PIN proteins exhibit synergistic interactions, which involve cross-regulation of PIN gene expression in pin mutants or plants with inhibited auxin transport. Auxin itself positively feeds back on PIN gene expression in a tissue-specific manner through an AUX/IAA-dependent signalling pathway. This regulatory switch is indicative of a mechanism by which the loss of a specific PIN protein is compensated for by auxin-dependent ectopic expression of its homologues. The compensatory properties of the PIN-dependent transport network might enable the stabilization of auxin gradients and potentially contribute to the robustness of plant adaptive development.

Arabidopsis↗

PubMed2005

Regulation of short-distance transport of RNA and protein.

The intercellular trafficking of proteins and RNAs has emerged as a novel mechanism of cell-cell communication in plant development. Plasmodesmata (PD), intercellular cytoplasmic channels, have a central role in cell-cell trafficking of regulatory proteins and RNAs. Recent studies have demonstrated that plants use either a selective or a non-selective PD trafficking pathway for regulatory proteins. Moreover, plants have developed strategies to regulate both selective and non-selective movement. Recent work has focused especially on integrating the recent understanding of the function and mechanisms of intercellular macromolecule movement through PD.

DNA, Plant↗

PubMed2002

Prevention of stomatal closure by immunomodulation of endogenous abscisic acid and its reversion by abscisic acid treatment: physiological behaviour and morphological features of tobacco stomata.

Transgenic tobacco ( Nicotiana tabacum L.) plants ubiquitously accumulating a single-chain variable-fragment (scFv) antibody against abscisic acid (ABA) to high concentrations in the endoplasmic reticulum (RA plants) show a wilty phenotype. High stomatal conductance and loss of CO(2) and light dependence of stomatal conductance are typical features of these plants. ABA was applied to these plants either via the petioles or by daily spraying over several weeks in order to normalise the phenotype. During the long-term experiments, scFv protein concentrations, total and (calculated) free ABA contents, and stomatal conductance and its dependence on CO(2) concentration and light intensity were monitored. The wilty phenotype of transgenic plants could not be normalised by short-term treatment with ABA via the petioles. Only a daily long-term treatment during plant development normalised the physiological behaviour completely. Scanning electron microscopy of stomata showed morphological changes in RA plants compared with wild-type plants that, for structural reasons, prevented regular stomatal movements. After long-term treatment with ABA this defect could be completely eliminated. Guard-cell-specific expression of the anti-ABA scFv did not cause any changes in physiological behaviour compared to the wild type. In addition, mesophyll-specific expression starting in leaves that were already fully differentiated resulted in normal phenotypes, too. We conclude that changes in distribution and availability of ABA in the cells of developing leaves of RA plants cause the development of structural features in stomata that prevent normal function.

Abscisic Acid↗

PubMed2002

The energy-conserving and energy-dissipating processes in mitochondria isolated from wild type and nonripening tomato fruits during development on the plant.

Bioenergetics of tomato (Lycopersicon esculentum) development on the plant was followed from the early growing stage to senescence in wild type (climacteric) and nonripening mutant (nor, non-climacteric) fruits. Fruit development was expressed in terms of evolution of chlorophyll a content allowing the assessment of a continuous time-course in both cultivars. Measured parameters: the cytochrome pathway-dependent respiration, i.e., the ATP synthesis-sustained respiration (energy-conserving), the uncoupling protein (UCP) activity-sustained respiration (energy-dissipating), the alternative oxidase(AOX)-mediated respiration (energy-dissipating), as well as the protein expression of UCP and AOX, and free fatty acid content exhibited different evolution patterns in the wild type and nor mutant that can be attributed to their climacteric/nonclimacteric properties, respectively. In the wild type, the climacteric respiratory burst observed in vitro depended totally on an increse in the cytochrome pathway activity sustained by ATP synthesis, while the second respiratory rise during the ripening stage was linked to a strong increase in AOX activity accompanied by an overexpression of AOX protein. In wild type mitochondria, the 10-microM linoleic acid-stimulated UCP-activity-dependent respiration remained constant during the whole fruit development except in senescence where general respiratory decay was observed.

Adenosine Triphosphate↗

PubMed2000

Regulation of cell division and the cytoskeleton by mitogen-activated protein kinases in higher plants.

The microtubule-associated protein 2 kinase (MAP2-kinase), now better known as mitogen-activated protein kinase (MAPK), was initially discovered in association with the cytoskeleton, and was later also implicated in cell division. The importance of mitogenic stimulation in plant development roused interest in finding the plant homologues of MAPKs. However, data on plant MAPKs in cell division are rather sparse and fragmentary. Therefore we place the available information on cell cycle control of MAPKs in plants into a broader context. We discuss four aspects of cell division control: cell proliferation and the G1/S-phase transition, G2-phase and mitosis, cytokinesis, and cytoskeletal reorganisation. Future work will reveal to what extent plants use signalling pathways that are similar or different to those of animal or yeast cells in regulating cell divisions.

Cell Division↗