Abstract
The anatomical structure of ‘Sattabhud’ lotus (
Nelumbo nucifera
Gaertn.) petal on the first day of soaking
in distilled water consisted of one layer of epidermis, layers
of mesophyll and vascular
tissue. Structure and shape
of cells were turgid cells with distinct cytoplasm. Afte
r 3 days of soaking, the peta
l tissues showed a tremendous
change of cells and tissues particularly the epidermis
and parenchyma. The parenchyma cells lost their round or
polyhedral shape with observed shrinkag
e and separation of protoplasm from
cell wall. The ultrastructure of petal
cells indicated that browning caused from the deteri
oration of epidermis and mesophyll parenchyma cells
particularly collapsed of cells, precipitation of substanc
es in cytoplasm and shrinkage of protoplasm. This also
resulted in synthesis of toxic me
tabolites and petal turning black.
Keywords:
lotus, ultrastr
ucture, browning
Introduction
The lotus flowers usually turn brown or black within 1-
2 days after harvest resultin
g in short vase life. This
is a very serious postharvest problem for cut lotus flower. Therefore, to learn about the anatomical and ultracellular
changes during the browning process is
necessary for solving this problem.
Materials and Methods
The ‘Sattabhud’ lotus flowers were harvested from
Chonburi province, Thailand
on July, 2009. The flower
peduncle(36 cm in length) was immediately soaked in distille
d water. The petals of ‘Sattabhud’ lotus were studied
on their anatomical and ultrastructura
l changes on the first day and after
3 days of harvest. The plant micro-
technique process was employed
. The samples cut with
ultra microtome of Leica UCT were stained with toluidine
blue, uranyl acetate and lead citrate. These samples we
re investigated by a compound microscope (Zeiss with
Azio plus II) and a
transmitting electron microscope(Joel;JEM 1220).
Results and Discussion
1. Anatomy of ‘Sattabhud’
lotus petals on the first day
The petals of ‘S
attabhud’ lotus were composed of one-cell
layer of upper on lower epidermis. The
cell had a nipple papilla shape, 3 sides rather thick of
cell wall, and some cells con
tained phenolic compound in
the cytoplasm. The mesophyll layer con
sisted of 1 - 3 layers of parenchy
ma cells, in compact arrangement
beneath the epidermal layer. The parenchyma cells were round
or polyhedral in shape, rather thick in cell walls
and consisted
of numerous phenolic compound in all of the cells
and resin substance in some cells. In the middle
region of petals, the parenchyma and aer
enchyma cells were rather
loose in arrangement fo
rming a large air space.
The air spaces were alternately arranged with vascular bu
ndle. The dispersed resin cel
ls were commonly found in
the middle of petals and in the vascular tissues. The va
scular tissue was composed of phloem and xylem in the
collateral type arrangement (Fig. 1 - 2).