ABSTRACT
Genetic model organisms have revolutionized science, and today, with the rapid advances in technology, there is significant potential to launch many more plant species towards model status. However, these new model organisms will have to be carefully selected. Here, we argue that Hemerocallis (daylily) satisfies multiple criteria for selection and deserves serious consideration as a subject of intensive biological investigation. Several attributes of the genus are of great biological interest. These include the strict control of flower opening and, within a short period, the precisely regulated floral death by a programmed cell death system. The self-incompatibility system in Hemerocallis is also noteworthy and deserves more attention. Importantly, the genus is widely cultivated for food, medicinal value and ornamental interest. Hemerocallis has considerable potential as a 'nutraceutical' food plant and the source of new compounds with biomedical activity. The genus has also been embraced by ornamental plant breeders and the extraordinary morphological diversity of hybrid cultivars, produced within a relatively short time by amateur enthusiasts, is an exceptional resource for botanical and genetic studies. We explore these points in detail, explaining the reasons why this genus has considerable value-both academic and socio-economic-and deserves new resources devoted to its exploration as a model. Its impact as a future model will be enhanced by its amenability to cultivation in laboratory and field conditions. In addition, established methods for various tissue and cell culture systems as well as transformation will permit maximum exploitation of this genus by science.
ABSTRACT
In addition to its importance in studies of plant reproduction and fertility, pollen is as widely employed as a model system of cell growth and development. This work demands robust, reproducible methods to induce pollen germination and morphologically normal growth of pollen tubes in vitro. Despite numerous advantages of Arabidopsis thaliana as a model plant, such experiments on pollen germination and pollen tube growth have often proved challenging. Our new method employs a physical cellulosic membrane, overlying an agarose substrate. By modulating the substrate composition, we provide important insights into the mechanisms promoting pollen growth both in vitro and in vivo. This effective new technical approach to A. thaliana pollen germination and tube growth results in swift, consistent and unprecedented levels of germination to over 90%. It can also promote rapid growth of long, morphologically normal pollen tubes. This technical development demonstrates that exogenous spermidine and a cellulosic substrate are key factors in stimulating germination. It has potential to greatly assist the study of reproduction in A. thaliana and its closest relatives, not only for the study of germination levels and pollen tube growth dynamics by microscopy, but also for biochemical and molecular analysis of germinating pollen.
