Overexpression of SOS (Salt Overly Sensitive) Genes Increases Salt Tolerance in Transgenic Arabidopsis

Abstract

Soil salinity is a major abiotic stress that decreases plant growth and productivity. Recently, it was reported that plants overexpressing AtNHX1 or SOS1 have significantly increased salt tolerance. To test whether overexpression of multiple genes can improve plant salt tolerance even more, we produced six different transgenic Arabidopsis plants that overexpress AtNHX1, SOS3, AtNHX1+SOS3, SOS1, SOS2+SOS3, or SOS1+SOS2+SOS3. Northern blot analyses confirmed the presence of high levels of the relevant gene transcripts in transgenic plants. Transgenic Arabidopsis plants overexpressing AtNHX1 alone did not present any significant increase in salt tolerance, contrary to earlier reports. We found that transgenic plants overexpressing SOS3 exhibit increased salt tolerance similar to plants overexpressing SOS1. Moreover, salt tolerance of transgenic plants overexpressing AtNHX1+SOS3, SOS2+SOS3, or SOS1+SOS2+SOS3, respectively, appeared similar to the tolerance of transgenic plants overexpressing either SOS1 or SOS3 alone.

Global plant-responding mechanisms to salt stress: physiological and molecular levels and implications in biotechnology

“…For example, over expression of the syntheses genes of Pro and GB can improve the content of Pro and GB obviously and endow the transgenic plants with enhanced tolerance (Kavi et al, 1995;Waditee et al, 2005). Similarly, the transgenic plants with more SOS1 or NHX1 transporters are able to regulate ion transport more quickly and effectively to grow well under salt stress (Liu et al, 2000;Quintero et al, 2002;Yang et al, 2009). Increasing the antioxidants through genetic engineering is widely adopted in breeding to produce crops with enhanced salt stress.…”

Tonoplast calcium sensors CBL2 and CBL3 control plant growth and ion homeostasis through regulating V-ATPase activity in Arabidopsis

“…The fusion constructs were introduced into Arabidopsis mesophyll protoplasts prepared from rosette leaves by the polyethylene glycol-mediated transformation procedure [59], respectively. For stable expression, the CBL2-YFP or CBL3-YFP fusion was cloned downstream of a plant super promoter in the pCAMBIA 1300 binary vector [60], and the resulting constructs were transferred into Agrobaterium tumefaciens GV3101 strain. Arabidopsis plants were transformed using the floral dipping method [57].…”

Salinity Stress and Salt Tolerance

“…In spite of the molecular identity of Na + sensor(s) remaining elusive, the plasma-membrane Na + /H + antiporter SALT OVERLY SENSITIVE1 (SOS1) is a possible candidate (Silva & Gerós, 2009). In fact, in Arabidopsis, ion homeostasis is mediated mainly by the SOS signal pathway (Yang et al 2009). SOS proteins are sensor for calcium signal that turn on the machinery for Na + export and K + /Na + discrimination (Zhu, 2007).…”

“…Transgenic plants overexpressing the genes participating in the synthesis or accumulation of osmoprotectants that function for osmotic adjustment, such as proline (Kishor, Hong, Miao, Hu, & Verma, 1995), glycinebetaine (Holmström, Somersalo, Mandal, Palva, & Welin, 2000) or other osmolytes show increased salt tolerance. Other genes that encode enzymes that are involved in oxidative protection, such as glutathione S-transferase, peroxidase, superoxide dismutase, ascorbate peroxidases, and glutathione reductases, can also be modified to improve plant salt tolerance (Yang, Chen, Zhou, Yin, Li, Xin, et al, 2009). Overexpression of regulatory genes in signalling pathways, such as transcription factors (DREB/CBF) and protein kinases (MAPK, CDPK) also increases plant salt tolerance (Chen, Ren, Zhong, Jiang, & Li, 2010).…”