Single-cell RNA sequencing of developing maize ears facilitates functional analysis and trait candidate gene discovery

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CLAVATA Signaling Ensures Reproductive Development in Plants across Thermal Environments

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The effect of growth regulators on shoot propagation and rooting of common lavender (Lavandula vera DC)

Nodal segments from micropropagated plants were used to evaluate the effect of growth regulators on the in vitro shoot proliferation and rooting of Lavandula vera DC. The highest multiplication rate was obtained using MS medium supplemented with 1.0 mg l^-1 of TDZ (2.25 μM) or BA (2 μM). Hyperhydricity occurred at high concentrations of these growth regulators. Rooting of the plantlets was obtained in all the media evaluated. However, rooting rates and root growth increased with increased concentrations of NAA and the reduction of the salt strength of the media. The plantlets were successfully transferred to soil and grown to maturity, exhibiting a normal development, with high uniformity and no evidences of somaclonal variation. This revised version was published online in June 2006 with corrections to the Cover Date.     

Micropropagation of floribunda,ground cover and miniature roses

Cultures were initiated from meristems (0.5 mm) of the rose cultivar Queen Elizabeth (floribunda) and from both shoot-tips and nodal explants (3–5 mm) of cultivars Sunburst Red, Toy Clown (miniatures) and Fiona (ground cover). Average proliferations of 5.0, 3.1, 1.3 and 2.5 shoots were obtained per culture cycle respectively on Murashige & Skoog (MS) medium with BA (1.0 mg l^-1), NAA (0.1 mg l^-1) and GA₃ (0.1 mg l^-1). With cv. Fiona, the proliferation rate was more than doubled by removal of the shoot apex. The rate of proliferation of cv. Queen Elizabeth was significantly increased by using long shoots (>2 cm in length) and by re-culturing shoots to fresh medium every 3 weeks. In vitro rooting percentage with cv. Queen Elizabeth was enhanced by using long shoots (>2 cm) and by dilution of MS medium to 1/4 strength. Transfer of shoots for direct rooting in compost was significantly improved by pre-culturing shoots for two weeks in vitro in media containing IAA, and by the use of sorbarods.     

Development of white spruce somatic embryos: II. Continual shoot meristem development during germination

Summary This study compares the development of shoot apical meristems of white spruce somatic and zygotic embryos during germination. In mature somatic embryos, the functional part of the shoot apical meristem was bi-layered. After partial drying, a normal shoot meristem was formed from these two cell layers during germination. Other cells within the meristem were vacuolated and separated by intercellular air spaces. In the absence of the partial drying treatment, somatic embryos enlarged in size primarily due to vacuolation of cells and the formation of large intercellular air spaces. A majority of these somatic embryos failed to form a functional shoot apical meristem. Compared with somatic embryos, the shoot apical meristem of a mature zygotic embryo was well organized with a densely cytoplasmic apical layer. The cells within the meristem were tightly packed. Judging from the cell profiles during germination, all cells within the meristem of the zygotic embryo took part in the formation of the vegetative shoot apical meristem.     

Expression of form and pattern in plants — a role for biophysical fields

Coordinated or ‘field’ behaviour of cells of a tissue can be treated as an interaction between signals and a responding system. When the response involves the reaction of similar cells to a gradient, the field properties are thought to reside mainly in the signal. It is not generally recognized that initially uniform properties in the responding tissue can contribute to the specification of geometrical detail. One such feature is that a tissue may have an intrinsic wavelength, e.g. for the diameter of a new-forming organ. Another is tensor properties. Both features can greatly expand the role of signals in the expression of pattern.     

A single-cell analysis of the Arabidopsis vegetative shoot apex

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