In spermatophytes the ovules upon fertilization give rise to the seeds. It is essential to understand the mechanisms that control ovule number and development as they ultimately determine the final number of seeds and, thereby, the yield in crop plants. In Arabidopsis thaliana, ovules arise laterally from a meristematic tissue within the carpel referred to as placenta. For a correct determinati...

Hypothesis: Sex allocation theory predicts that the pollen–ovule ratio should increase linearly with increasing seed size among seed plants (Charnov, 1982). Data examined: We retrieved data for the pollen–ovule ratio, seed size, and possible confounding variables (ovule number, plant height, mating system) from a database and additional literature for 299 gymnosperm plant species of the German ...

Hypothesis: Sex allocation theory predicts that the pollen-ovule ratio should increase linearly with increasing seed size among seed plants (Charnov 1982). Data examined: We retrieved data for pollen-ovule ratio, seed size and possible confounding variables (ovule number, plant height, mating system) from a database and additional literature for 299 angyosperm plant species of the German flora....

Factors affecting reliable plant regeneration from unfertilized ovule culture of gentians (Gentiana spp.) were examined. Cold pretreatment (4°C) of flower buds enhanced or maintained production of embryo-like structure (ELS). When 43 genotypes were surveyed in two different labs, 40 of them produced ELSs ranging from 0.01 to 26.5 ELSs per flower bud. No ELSs could be obtained in three genotypes...

Molecular and genetic analyses have demonstrated that the Arabidopsis thaliana gene BELL1 (BEL1) is required for proper morphogenesis of the ovule integuments. Several lines of evidence suggest that BEL1 may act, at least in part, to repress the function of the organ identity gene AGAMOUS (AG) during ovule development. To study the relative roles of BEL1 and AG, plants homozygous for ag, bel1 o...

Hypothesis: Sex allocation theory predicts that the pollen–ovule ratio should decrease linearly with increasing pollen size among seed plants (Charnov, 1982). Data examined: We retrieved data for pollen–ovule ratio, pollen size, pollen grain number, and mating system from published literature for 311 angiosperm plant species. Methods: We used model II regressions on cross-species data as well a...