| dc.description |
Seed germination sensu stricto is defined as the physiological events before the
radicle tip ruptures the covering tissues. The ability of the radicle to elongate (or
germination potential) is observed in developing embryos prior to completion of seed
maturation. When embryos at early developmental stages, such as globular, heart,
torpedo or walking-stick are excised and grown in media, germination potential is not
observed. Following these stages, embryos start to acquire germination potential. This
thesis research focused on the mechanisms of the induction of germinability in
Arabidopsis thaliana (Arabidopsis) developing seeds. A mutant with embryo defects
was also analyzed in this research to gain insights into embryogenesis and
germination. The mutant named embryo ball (eb) arrests after the globular-like stage
yet continued cell growth to some extent. While desiccated mature eb seeds were
unable to germinate, if developing embryos were excised and placed on media, the
main root elongated. eb also exhibited abnormal root hair growth from the apical
portion of the embryo. The hypocotyl and cotyledons were missing in eb embryos in
mature seeds. When eb embryos were grown on media, vegetative leaf-like structures
with trichomes were formed and the main and subsequent lateral roots developed
normally. Some eb embryos exhibited desiccation tolerance which is characteristic of
wild-type (WT) mature embryos. Thus, while morphological maturation does not
seem essential for the induction of germination potential, physiological maturation of
the embryonic cells plays an important role in determining germination potential. |
|