RESUMO
The cleistogamous species Collomia grandiflora produces dimorphic cross-incompatible flowers on a single plant. The open or chasmogamous flower has smaller, flask-shaped stigmatic papillae, larger pollen grains, longer styles, and faster pollen tube growth rates down the style than the closed or cleistogamous flower. In intermorph crosses, pollen tube growth rates are greatly decreased and fertilization does not occur.
RESUMO
Our objective was to test whether accurate growth analyses can be obtained from anatomical records and some mathematical formulas. Roots of Zea mays L. were grown at one of two temperatures (19 degrees C or 29 degrees C) and were prepared with standard techniques for light microscopy. Positions of cell walls were digitized from micrographs. The digitized data were averaged and smoothed and used in formulas to estimate growth trajectories, Z(t), velocities, v(z), and strain rates, r(z), where Z(t) is the location occupied by the cellular particle at time t; and v(z) and r(z) are, respectively, the fields of growth velocity and strain rate. The relationships tested are: for Z(t), t = n * c; v(z) = l(z) * f; and r(z) = f * ( partial differential/ partial differentialz (l(z))). In the formulas, n represents the number of cells between the origin and the position Z(t); l(z) is local cell length; the constant c, named the ;cellochron,' denotes the time for successive cells to pass a spatial point distal to the meristem; l(z) is local cell length, and f is cell flux. Growth trajectories and velocity fields from the anatomical method are in good agreement with earlier analyses based on marking experiments at the two different temperatures. Growth strain rate fields show an unexpected oscillation which may be due to numerical artifacts or to a real oscillation in cell production rate.
RESUMO
Antiserum was raised in rabbits against a lily (Lilium longiflorum) anther-specific protein (LLA-15). Monospecific anti-LLA-15 antibodies were prepared to investigate the distribution of LLA-15 during anther development in a variety of flowering plants. Immunoblot analyses of total protein from floral and vegetative organs confirmed that LLA-15 or LLA-15-like proteins accumulated to detectable levels only in a discrete stage of anther development. In situ localization using anti-rabbit immunoglobulin G conjugated with gold particles confirmed that LLA-15 was specifically localized in the tapetal tissue of lily anthers. The maximal level of LLA-15 was strictly coincident with the peak of tapetal secretory functions. Immunoblots of two-dimensional polyacrylamide gels of lily anther proteins indicated that the seven LLA-15 isoforms ranged from isoelectric point 5.6 to 6.1. In vitro translation of lily anther mRNAs showed that four of these isoforms were primary products, the additional three being a result of posttranslational processing of the primary translation products.
RESUMO
Flowering plants possess specialized extracellular matrices in the female organs of the flower that support pollen tube growth and sperm cell transfer along the transmitting tract of the gynoecium. Transport of the pollen tube cell and the sperm cells involves a cell adhesion and migration event in species such as lily that possess a transmitting tract epidermis in the stigma, style, and ovary. A bioassay for adhesion was used to isolate from the lily stigma/stylar exudate the components that are responsible for in vivo pollen tube adhesion. At least two stylar components are necessary for adhesion: a large molecule and a small (9 kD) protein. In combination, the two molecules induced adhesion of pollen tubes to an artificial stylar matrix in vitro. The 9-kD protein was purified, and its corresponding cDNA was cloned. This molecule shares some similarity with plant lipid transfer proteins. Immunolocalization data support its role in facilitating adhesion of pollen tubes to the stylar transmitting tract epidermis.