Postembryonic organ formation in higher plants relies on the activity of stem cell niches in shoot and root meristems where differentiation of the resident cells is repressed by signals from surrounding cells. We searched for mutations affecting stem cell maintenance and isolated the semidominant l28 mutant, which displays premature termination of the shoot meristem and differentiation of the s...

Genetic analyses, particularly in Arabidopsis, have led to the identification of mutants that define different steps of ovule ontogeny, pollen stigma interaction, pollen tube growth, and fertilization. Isolation of the genes defined by these mutations promises to lead to a molecular understanding of these processes. Mutants have also been obtained in which processes that are normally triggered ...

Seed morphs of Calendula officinalis were investigated in order to examine the genetic variability which correlates with seed polymorphism and its impact on collection strategy of gene banks. The basic parameters to get the evidence were obtained from morphological data, karyotype analysis, electrophoretic pattern of seed proteins as well as nucleic acid analysis. Seven seed morphs were observe...

is the symbol used to describe an allele at the R locus that controls-together with certain complementary factors-anthocyanin pigmentation in both plant and seed. R factors that lack the capacity to elicit pigment formation either in plant or seed tissues, or in both, are designated as follows: Rg = colored seed, green plant; I ' = colorless seed, colored plant; 19 = colorless seed. green plant...

The present study was carried out to investigate laboratory germination responses of six collections of Garcinia kola seeds to six different hormonal pre-germination treatments. This consisted of soaking seeds for three days in cool distilled water (control), in cool distilled water supplemented with 10 M of either naphthaleneacetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), benzylamin...

1. The variability of species combinations and membership assembly patterns in an insect pre-dispersal seed predator guild were studied at various spatial and temporal resolutions using presence/absence and abundance data in null models. The guild consists of seven beetle species (four bruchids and three curculionids) and one moth species that live on a perennial vetch, Vicia tenuifolia Roth (L...

The scaffold protein RACK1 (Receptor for Activated C Kinase 1) serves as an integrative point for diverse signal transduction pathways. The Arabidopsis genome contains three RACK1 orthologues, however, little is known about their functions. It is reported here that one member of this gene family, RACK1A, previously identified as the Arabidopsis homologue of the tobacco arcA gene, mediates hormo...

A critical analysis of photoionization as the major process for seed electron production ahead of the cathode-directed streamer has been made. The accumulation of O2 ions between pulses and fast electron detachment in an electric field could be an effective source of seed electrons for repetitively pulsed discharges in electronegative gases. Measurements and two-dimensional calculations in the ...

Plant somatic cells have the remarkable ability to regenerate an entire organism. Many species in the genus Kalanchoë, known as "mother of thousands," develop plantlets on the leaf margins. Using key regulators of organogenesis (STM) and embryogenesis (LEC1 and FUS3) processes, we analyzed asexual reproduction in Kalanchoë leaves. Suppression of STM abolished the ability to make plantlets. Here...

Monodisperse nonspherical poly (methyl methacrylate) (PMMA) particles where a central core particle had grown two extra "lobes", or protrusions, placed opposite each other were successfully synthesized by swelling and subsequent polymerization of cross-linked PMMA spheres with methyl methacrylate and the cross-linker ethylene glycol dimethacrylate. The use of large (~3 μm) seed particles allowe...