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Legume Genomics and Genetics (online), 2010, Vol. 1, No.5, 24-29
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Figure 2 Hydrophobic plot of AhAQ1
Note: The hydrophobic values were calculated by the program
TMPRED (http://www.ch.embnet.org/software/TMPRED_form.
html); The amino acid residues 1~287 are presented at
X
-axis.
Areas above the x-axis indicate hydrophobic portions of the pro-
tein, and that under the line are hydrophilic ones. It shows that
there are at least 6 possible membrane-spanning regions in the
AhAQ1; 1~6: 6 transmembrane domains; A,B: NPA box
quantitative RT-PCR. The results showed that the
transcripts of
AhAQ1
were responsive to salt stress in
three kinds of tissues. Transcript level of
AhAQ1
accu-
mulated rapidly within 1 h in the leaves and stems
exposed to high salt stress, then decreased as the same
level as the control 12 h and 24 h later, respectively.
In the treated roots,
AhAQ1
was transiently induced at
6 h after treatment (Figure 5). These results show that
AhAQ1
is induced under salt stimulation, which su-
ggests that it may be functional during the stress.
2 Discussion
Aquaporins contain six membrane-spanning domains
linked by five loops and two conserved NPA motifs
that lies in loop B and E, the mutation of which will
lead to the loss of their function (Perston et al., 1994),
Both their N- and C-terminal are located on the cytop-
lasmic side of the membrane. Since the amino acid
sequence of AhAQ1 presented all the structure chara-
cters of aquaporin, it was normally considered to be
an aquaporin in peanut.
Many studies conformed that water stress has a strong
influence on aquaporin gene expression, and both in-
duced, reduced, or unchanged patterns have been re-
ported (Yamaguchi-Shinosaki et al., 1992; Baiges et
al., 2002; Kawasaki et al., 2001; Grote et al., 1998 ).
Three PIP genes,
NtPIP1
;
1
,
NtPIP2
;
1
and
NtAQP1
were
isolated from tobacco plants. Under drought stress, the
accumulation of NtPIP1;1 and NtPIP2;1 transcripts
was significantly decreased, however that of the Nt-
AQP1 transcript was increased (Mahdieh et al., 2008).
The various expression patterns of aquaporins under
water stress suggest that the molecular mechanism of
Figure 3 Alignment of AhAQ1 with PIP2-type proteins in other plants
Note: Positions containing identical residues are shaded in black, while conservative residues in grey; The transmembrane domains
and NPA motif are lined; The alignment was performed using ClustalX (ver 1.81) program and viewed by GeneDOC software
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