Molecular Plant Breeding2016, Vol.7, No.18, 1
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enrichment and folding of nascent protein that thermally induced synthesis in cytosol and organelles associates
with other molecular chaperones, it also can reduce membrane damage of plant in cold environment, enhance the
cold resistance of organization, and closely associated with plant acquired tolerance (Lin et al., 2001). Huang
Shangzhi et al., (2004) found that the cold resistance of the rice seedlings was significantly enhanced if the seeds
were treated by 42°C heat shock during germination. Molecular chaperone Cpn60-α1 subunits in cytoplasm can
combine Rubisco large subunit (Chen, 2000) to help protein correctly folding and free from the interference of
other proteins. The expression of Hsp17.6I was increased in the process of
L. apetalum
seeds relieving
low-temperature stagnancy, it improve the cold tolerance of
L. apetalum
.
Peroxidase (POD) is a protective enzyme within plant cells, it is related to the plants resistance to low temperature
and other adverse environment. In a certain range of temperature, the POD activity increase with the increase of
temperature (Liu, 2001). Per12 and Per28 are typical members of oxidoreductase family Ш (Tognolli et al., 2002),
they belongs to the transmembrane protein, and mainly exist in the vacuole. Their expressions are induced by the
environment in the early development of seed, and they have many cofactor bindings to enzyme, such as Heme b
and Ca2+ binding sites (Theologis et al., 2000; Dunand et al., 2002). When plant tissues are subjected to
environmental stresses such as trauma, pathogen invasion, and oxidative stress, they can remove H
2
O
2
, a toxic
reducing agent, rely on various isozyme subtypes; synthetize and degradation lignin, cork, and metabolise auxin
(Schenk et al., 2000). The peroxidase content increases in
L. apetalum
seeds which are stimulated by short-term
high temperature in low temperature stratification period, it is conducive to remove H
2
O
2
, and improve
L.
apetalum
tolerance to low temperature. However, inhibiting the expression of certain peroxidase genes such as
ascorbate peroxidase (APX) (Sung et al., 2005) during the early germination, H
2
O
2
can be accumulated to
stimulate seed germination and improve the germination rate. Therefore, although the increase of the peroxide in
the process of
L. apetalum
seeds removing germination stagnancy can protect
L. apetalum
from low temperature
damage, but it not the key gene to promote the germination.
Cell division control protein E (Cdc48E) belongs to the family of AAAATPase, it mainly located in the nucleus. In
the process of cell division, Cdc48E positioned on a film body along with the formation of the new cell wall, and
play a role in the process of cell division and growth by fusion with the same type of organelles (Tabata et al.,
2000; Seki et al., 2002). Cdc48E typically contains 809 amino acids, it highly expressed in the vigorous growth of
cells such as bud of
Arabidopsis thaliana
, and it participated in the formation of new cell wall, as well as the
disintegration and reconstruction of the nuclear envelope (Yamada et al., 2003; Saracco et al., 2009). After the
L.
apetalum
seeds stratificated at low temperature for 10 d, was treated at 25°C for 1 hour, Cdc48E protein content
increased significantly in the seeds, it promotes the cell cycle and is beneficial to the further growth and
development of embryonic cells.
In this study, gene expression of
L. apetalum
seeds in different periods of low-temperature germinate was
analyzed and discussed from transcription level and protein level respectively. Results showed that the expression
of cell division control protein E gene (
CDC48E
), peroxidase 12 genes (
PER12
) and small heat shock protein
gene (
HSP17.6
) were significantly up-regulated in
L. apetalum
seeds, the seeds of low-temperature stratification
and was treated in 25°C for a period of time. This is consistent with the results of protein expression. The
germination rate of
L. apetalum
seeds in germination stagnancy was affected by the length of 25°C treatment, and
it increased significantly with the increase of treatment time. The phenotypic results also corroborated that short
treatment at 25°C will affect the expression of certain genes of
L. apetalum
seeds in low temperature stratification,
and the products of these genes expression will exert beneficial effects on
L. apetalum
seeds germination at low
temperature. Low temperature is one of the key adverse factors that affect the yield of crops. Research on the key
factor of
L. apetalum
seeds germination at low temperature can help to understand the molecular mechanism of
low-temperature germination, and ultimately provides the basis for modifying crop genetic shape.
3 Materials and Methods
3.1 Materials and treatment
L. apetalum
seeds were collected in LiYv hill, Urumqi, Xinjiang. Plump mature seed was selected and stored at
