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POSTEMBRYONIC
DEVELOPMENT OF CISTANCHE TUBULOSA (SCHRENK) WHIGT
CHEN
QING-LIANG1,2, JIA YA-MIN2, WANG ZHI-FEN1*,
SHAN CHENG-GANG1, ZHU
JING-BIN1
AND GUO YU-HAI2
Abstract:
The embryo of
the mature seed of the parasitic angiosperm Cistanche tubulosa
(Schenk) Whigt remains at pro-embryo stage. Little is known about the
establishment of shoot and root apical meristems at poles of the
embryonic body during postembryonic development. Thus, structure of the
embryo of the mature seed and how and what the shoot and root apical
meristems develop into during postembryonic development were
investigated using light and dissecting stereo-microscopes. In the
mature seed, the plumular pole of the embryo consists of large
vacuolated, dense cells, containing starch granules and the radicular
pole consists of decidedly smaller and denser cells lacking starch.
During seed germination and parasitization, plumular pole cells expired
without forming the apical meristem or cotyledons; while radicular pole
cells formed a meristematic zone, which developed into a young parasite.
We therefore conclude that: (1) the embryo of Cistanche consists
of a nutrient-storage region (the plumular pole) and a meristematic
region (the radicular pole); (2) during postembryonic stages, the
plumular pole performs storage function and supplies its stored
nutrients as well as those of the endosperm to the radicular pole; the
radicular pole was the only origin of the apical meristems forming
Cistanche. This study provides some useful information on the
embryology of the parasitic plant and elucidates the basis for
ecological adaptation and evolutionary strategy of this plant.
1Institute
of Agro-food Science & Technology/Research Center for Medicinal Plants,
Shandong Academy of Agricultural Sciences, Jinan 250100, China
2Chinese
Medicinal Herbs Research Center, College of Agronomy and Biotechnology,
China Agricultural University, Beijing 100094,
China
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