Environmental Engineering Reference
In-Depth Information
contents of Na
+
, K
+
, Cl
-
and K
+
/Na
+
ratio and the conclusions were coincide with the
foregoing results. From Figure 3.3.1 and Figure 3.3.2, we can see that the contents of Na
+
and
Cl
-
were increased obviously by NaCl stress, but the K
+
was lessened. For the young
seedlings, the increase of the Na
+
and Cl
-
concentrated mainly on leaves, while the decrease
of the K
+
was duo to the change in roots, reflecting their different regulating mechanism. The
changes of the K
+
/Na
+
ratio in leaves were more severe than roots, especially for the roots of
wild soybean, and the changing is tiny (Figure 3.3.1). In addition, the K
+
/Na
+
ratio in wild
soybean was exceed the cultivated soybean under all the treatments in both root and leaf
(Figure 3.3.1, 3.3.2). In mature seedlings, the situation was almost the same (Figure 3.3.1).
Notably, the advantageous of wild soybean was not as distinct as young seedlings. Generally,
compared with cultivated soybeans, the amplitude of variation of the ion contents in wild
soybean was smaller, suggesting that the wild soybean had better resistance.
4.4. The NMT Revealed the Real-Time Ion Fluxes and Suggested that the
Wild Soybean Had Quicker Na
+
, Cl
-
Efflux and H
+
Influx, as well as Slower
K
+
Efflux
Compared to the ion levels changing, the NMT gave us a more ocular and quicker
detection, and the wild soybean exerted more outstanding superiority. Both in young and
mature seedlings, the Na
+
and Cl
-
were ejected to the extracellular more quickly, and the H
+
was imported into cells faster in wild soybean (Figure 3.4.3, 3.4.4). The K
+
on the other hand
was discharged from cells more slowly, reflecting that the wild soybean had better abilities to
maintain K
+
(Figure 3.4.3, 3.4.4). These results coincided with the emulative absorptions of
K
+
and Na
+
[15]. Unlike animals, the plant cells make use of the H
+
-ATPases nor Na
+
-
ATPases, which they do not have, to create a proton-motive force to drive the afflux of the
Na
+
. Therefore, the enhanced H
+
influx in wild soybean in fact was an indirect reflection of its
salt resistance. Under 300 mM NaCl in special, the flux of H
+
in cultivated soybean was
almost arrived 0, (Figure 3.4.3, 3.4.4) reflecting that the stress has produced serious damage,
while the flux in wild soybean to the contrary still maintained a steady rising trend. The
conditions of Cl
-
were the same. So we can realize that the wild soybean had better salt
tolerance and the capability was more obvious under high salt concentration. With an
increasing number of H
+
entered the cells, more and more Na
+
were transferred out of the
cells by H
+
/Na
+
at the same time, and the same theory had already been elaborated in Poplar
(Sun et al., 2009). In addition, it has been reported that the activity of the plasma membrane
(PM) Na
+
/H
+
anti-porters could be induced by NaCl, and many related researches on
transporters such as SOS1, NHXs have also acquired similar conclusions (Ji et al., 2013;
Jiang, 2010; Martinez-Atienza et al., 2007; Qiu, Barkla, Vera-Estrella, Zhu, and Schumaker,
2003). For the mature seedlings, there were the same conclusions. The most obvious
differences between them were still emerged on 300 mM NaCl. Nonetheless the gap was not
as large as young seedlings, especially for the influx of K
+
.
