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THE MORPHOLOGY AND
ANATOMY OF THE HAUSTORIA OF THE HOLOPARASITIC ANGIOSPERM CUSCUTA
CAMPESTRIS
LAN HONG1,2,*,
HAO SHEN2,*, HUA CHEN2,3,†, LING LI1,
XIAOYING HU2, XINLAN XU2, WANHUI YE2
AND ZHANGMING WANG2
Abstract:
The morphology
and anatomy of the haustoria of the holoparasitic angiosperm Cuscuta
campestris parasitizing itself and different tissues of Mikania
micrantha were studied under scanning electron microscope, confocal
laser scanning electron microscope and light microscope. C.
campestris has a low stomatal density on the stem and there is a
nonfunctional conical protuberance with a unique elliptic pore at the
apex, which has not been reported before and we call it
pseudo-haustorium. The pseudo-haustorium originates from the cortical
parenchyma just external to the pericycle. Its initial cells divide
anticlinally and periclinally, and then develop into an endophyte
primordium, which consists of file cells and meristematic cells. When
C. campestris infects host stem, petiole, leaf lamina and itself, it
prefers host stem and has the least choice for leaf lamina. The
development of the haustoria invading different tissues reveals that the
haustorium in the leaf lamina region without veins is initially flat and
its search hyphae does not differentiate into xylem and phloem hyphae,
which differs from the haustoria with the annular vessel and phloem
hyphae in host stem, petiole and its own stem. These indicate that the
haustoria might differentiate vascular tissues only when their search
hyphae come in with the contact the vascular tissues of the host or
itself.
1College
of Life Sciences, Guangdong Key Lab of Biotechnology for Plant
Development, South China Normal
University, Guangzhou 510631, China;
2Key
Laboratory of Plant Resources Conservation and Sustainable Utilization,
South China Botanical Garden, hinese Academy of
Sciences, Guangzhou 510650, China;
3Graduate
School of the Chinese Academy of Sciences, Beijing 100049, China.*
These
authors contributed equally to this study.
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