Soil salinity is a major environmental constraint to crop production, affecting an estimated 45 million hectares of irrigated land, and is expected to increase due to global climate changes and as a consequence of many irrigation practices. The deleterious effects of salt stress on agricultural yield are significant, mainly because crops exhibit slower growth rates, reduced tillering and, over months, reproductive development is affected.

1. Role of Organelle Membranes in Salt
Stress Sensing and Signalling in Plants
112/1/2019
Antre Suresh H.
1st Year Ph. D.
PALB 8086
Plant Biotechnology
UAS(B)

2. 12/1/2019 2
 Salinity stress reduces water potential, thereby preventing water
uptake by roots and provoking a set of responses similar to those of a
water deficit.
 Causes - osmotic stress, salinity provokes the stomatal limitation of
photosynthesis, loss of turgor, enhanced photorespiration, and excess
production of ROS.
 The ionic component of salinity stress is attributed to the direct toxic
effects of Na+ and imbalances in the homeostasis of other ions such as
K+ and Ca2+.

3. 12/1/2019 3
The three main mechanisms of salinity tolerance in a crop plant.
Roy et al., 2014

4. 12/1/2019 4
Na+ uptake and translocation in glycophytes via Na+ and/or K+
transporters and channels
Assaha et al., 2017

5. 512/1/2019
Intracellular Na+ homeostasis mediated by Na+ transporters and
channels and their regulatory elements
Assaha et al., 2017
(PM) H+-ATPase
(TP) H+-ATPase
(TP) H+-pyrophosphatase

6. 12/1/2019 6
PM H+/ATPases are at the center of K+ uptake under salt
stress and low-K+ conditions
Assaha et al., 2017
(PM) H+-ATPase
(TP) H+-ATPase
(TP) H+-pyrophosphatase

7.  Salt stress can induce cell death by depleting cytosolic K+ beyond a threshold level.
Thus, under saline environments, maintaining an optimal K+/Na+ ratio inside the
cytosol is critical for normal functioning of cytoplasm.
 Rapid regulation of the plasma membrane H1-ATPase activity is essential for
salinity tolerance in halophyte
Bose et al., 2015
712/1/2019
Arabidopsis Halophytes

8.  Salt stress increases ROS
production (Bose et al., 2014),
with chloroplasts and
peroxisomes producing 20-fold
more ROS than mitochondria
during the day.
 The major ROS produced in
chloroplasts are hydrogen
peroxide (H2O2), superoxide
radical (O2 •−), hydroxyl radical
(•OH) and singlet oxygen (1O2).
812/1/2019 Bose et al., 2014

9. chloroplast Na+, Cl− and K+ transporters with a
proposed role in salt tolerance
912/1/2019
Number of chloroplasts per cell response
to salt exposure.
 The halophytes can overcome stomatal limitation by switching to CO2 concentrating
mechanisms and increasing the number of chloroplasts per cell under saline conditions.
 salt entry into the chloroplast stroma may be critical for grana formation and photosystem
II activity in halophytes but not in glycophytes.

10. Salinity-Induced Diverse ROS Scavenging Pathways in Chloroplasts
Int. J. Mol. Sci. 2017
1012/1/2019

11. 1112/1/2019

12. 12/1/2019 12
Cntd. . .

13. Salt tolerance pathways in chloroplasts
1312/1/2019

14. 12/1/2019 14
The Ca2+/salt overly sensitive
(SOS) cascade.
GIGANTEA (GI) regulates salt stress
response.
Othman et al., 2017

15. 12/1/2019 15
The cellular salinity signalling network and its connection to
mitochondrial functions
Othman et al., 2017

16. 12/1/2019 16
Ca2+ / ROS signaling network involved in osmotic responses under salinity
stress
Kurusu et al., 2015
Summary

17. 12/1/2019 17
Reference :
Aldesuquy, H., Baka, Z. and Mickky, B., 2014. Kinetin and spermine mediated induction of salt tolerance in wheat plants: Leaf area,
photosynthesis and chloroplast ultrastructure of flag leaf at ear emergence. Egyptian journal of basic and applied sciences, 1(2),
pp.77-87.
Assaha, D.V., Ueda, A., Saneoka, H., Al-Yahyai, R. and Yaish, M.W., 2017. The role of Na+ and K+ transporters in salt stress adaptation
in glycophytes. Frontiers in physiology,8, p.509-528.
Bose, J., Munns, R., Shabala, S., Gilliham, M., Pogson, B. and Tyerman, S.D., 2017. Chloroplast function and ion regulation in plants
growing on saline soils: lessons from halophytes. Journal of Experimental Botany, 68(12), pp.3129-3143.
Kubínová, Z., Janáček, J., Lhotáková, Z., Kubínová, L. and Albrechtová, J., 2013. Unbiased estimation of chloroplast number in
mesophyll cells: advantage of a genuine three-dimensional approach. Journal of experimental botany, 65(2), pp.609-620.
Suo, J., Zhao, Q., David, L., Chen, S. and Dai, S., 2017. Salinity response in chloroplasts: insights from gene
characterization. International journal of molecular sciences,18(5), p.1011.
Wang, X., Chang, L., Wang, B., Wang, D., Li, P., Wang, L., Yi, X., Huang, Q., Peng, M. and Guo, A., 2013. Comparative proteomics of
Thellungiella halophila leaves from plants subjected to salinity reveals the importance of chloroplastic starch and soluble sugars in
halophyte salt tolerance.Molecular & Cellular Proteomics, 12(8), pp.2174-2195.
Ye, W., Hu, S., Wu, L., Ge, C., Cui, Y., Chen, P., Wang, X., Xu, J., Ren, D., Dong, G. and Qian, Q., 2016. White stripe leaf 12 (WSL12),
encoding a nucleoside diphosphate kinase 2 (OsNDPK2), regulates chloroplast development and abiotic stress response in rice
(Oryza sativa L.). Molecular Breeding,36(5), p.57.
Zhang, J.T., Zhu, J.Q., Zhu, Q., Liu, H., Gao, X.S. and Zhang, H.X., 2009. Fatty acid desaturase-6 (Fad6) is required for salt tolerance in
Arabidopsis thaliana. Biochemical and biophysical research communications, 390(3), pp.469-474.