Environmental Engineering Reference
In-Depth Information
et al. 2009; Yan et al. 2013). The specific biochemical strategy contains: (1) Ion regulation
and compartmentalization, (2) Induced biosynthesis of compatible solutes, (3) Induction of
antioxidant enzymes, (4) Induction of plant hormones, (5) Changes in photosynthetic pathway
(Parida and Das 2005). The Molecular mechanism includes: (1) the SOS pathway for ion
homeostasis, (2) the protein kinase pathway for stress signaling, (3) the phytohormone
signaling pathway under high salt stress (Zhu 2002), (4) the associated genes encoding salt-
stress proteins, such as genes for photosynthetic enzymes, synthesis of compatible solutes,
vacuolar-sequestering enzymes and for radical-scavenging enzymes (Winicov 1998).
In recent years, tremendous advances have been achieved in salt stress studies. Plant
breeders have fostered some salt-tolerant lines of crops by conventional breeding, moreover
transgenic approach is employed to improve the crop salt tolerance and a number of
transgenic lines have been testified to be effective under control conditions (Ashraf and
Akram 2009). Metabolomics is becoming a tool to understand the cellular mechanism to
abiotic stress and acts as a viable option for the biotechnological improvement of halofhytes
(Ruan and Teixeira da Silva 2011). Small noncoding RNAs mainly coming down to
microRNAs and siRNAs (short interfering RNAs) can regulate gene expression by silencing
of the genes (Carrington and Ambros 2003). MiR393 has been discovered to be strongly up-
regulated by drought, high-salinity treatments (Dharmasiri et al. 2005; Kepinski and Leyser
2005). In the nearest, the ribosomal RNA methylation was discovered to response to abiotic
stress (Baldridge and Contreras 2013). In addition, the mitogen-activated protein kinase
(MAPK) signaling pathways which are involved in stress responses are the highly conserved
and important regulating system in plants (Colcombet and Hirt 2008; Sinha et al. 2011).
Reviews on salinity responses arose three decades ago, and new reports appeared
continuous (Zhu 2001; Munns and Tester 2008; Türkan and Demiral 2009; Flowers et al.
1977; Zhu 2003; Parida and Das 2005). The molecular, cellular and holistic mechanisms of
plant salt tolerance were discussed in detail (Munns and Tester 2008). Flowers et al. chose to
stand at the point of uptake and transport of ions to review the concrete mechanisms of salt-
tolerance (Flowers and Colmer 2008). Turkan and Demiral described how the plants manage
to control ion homeostasis by sensing, transduction and responding salt stress signaling
(Türkan and Demiral 2009). Thanks to the rapid development of life science, our
understanding of the salinity tolerance in both physiological and molecular fields has
experienced a qualitative leap. In this review we will focus on the molecular, cellular and
physiological mechanisms of the salt-tolerance in detail especially the latest findings in this
sphere.
G
ROWTH AND
P
HOTOSYNTHESIS
Environmental stresses can trigger various plant responses from gene expression,
metabolism all the way to growth rate and productivity (Shao et al. 2009). Salinity which is
the common and comprehensive negative influence can lead to an apparent stunting of plant
growth (Gorai et al. 2011; Tarchoune et al. 2011). From another point of view, slower growth
is an available measure for plant survival under stress (Zhu 2001). That is to say, the adverse
environments affect plant and the plant takes necessary measures to fit it. Actually, all the
physiological performances are the adaptive strategies for plant under salt stress. Research on
