The developmental programs of maturing seed and fruit in pea (Pisum sativum L.) are tightly controlled by the interactions of several phytohormones, including gibberellins (GAs), auxins, and abscisic acid (ABA). To more fully understand these hormone networks and their roles in controlling development, transcription profiles of GA metabolism genes and metabolite profiles of key GAs, auxins, and ABA were determined in developing seeds, and histological studies were employed to correlate physiology and hormone metabolism. Data suggest that bioactive GA stimulates several aspects of seed growth, and ABA appears to promote bioactive GA1 synthesis in rapidly growing seed coats, and inhibit GA biosynthesis in the embryo axes of maturing embryos. Two putative auxin receptor genes were cloned, and their transcription profiles examined in developing seed and pericarp tissues. Pericarp PsAFB6A transcription was responsive to auxin and seed signals, indicating a potential role for the modulation of auxin sensitivity in fruit development.

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Conclusions The role of AUXIN BINDING PROTEIN 1 (ABP1) in the auxin management in plant cells was followed using simplified model material of suspension-cultured cells of tobacco BY-2 line. ABP1 is a putative auxin receptor considered to mediate fast non-genomic responses to auxin and it can be involved in every aspect of the regulation of auxin responses, metabolism and transport. There are four major conclusions that could be made based on the results presented in this thesis: 1) Auxin binding protein 1 mediates both cell division and expansion in tobacco BY-2 cells. In standard cultivation conditions or at lower concentrations of 2,4-D in culture medium, ABP1 overexpression had no detectable impact on cell division, cell elongation or cell growth.. 5- times increased 2,4-D concentration stimulated weakly cell elongation. . Antisense suppression of ABP1 expression resulted in disturbance in both cell expansion and cell division intensity, suggesting that ABP1 is essential for the control of balance between cell division and cell elongation during the growth cycle. ABP1 is localized in endoplasmic reticulum of cells cultivated in standard medium supplemented with 1 μM 2,4-D and it appeared also at the plasma membrane following the IAA application. 2) ABP1 mediates intercellular auxin transport. Cells...