Transgenic expression of Prunus persica Salt Overly Sensitive 2 (PpSOS2) in atsos2 mutant imparts salt tolerance in Arabidopsis

Authors: KAUNDAL, AMITA - Utah State University; Sandhu, Devinder; SINGH, VISHAL - Utah State University; DUENAS, MARCO - University Of California; ACHARYA, BISWA - University Of California; NELSON, BRAD - Utah State University; Ferreira, Jorge; LITT, AMY - University Of California

Submitted to: ACS Agricultural Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2022
Publication Date: 1/24/2022
Citation: Kaundal, A., Sandhu, D., Singh, V., Duenas, M., Acharya, B.R., Nelson, B., Ferreira, J.F.S., Litt, A. 2022. Transgenic expression of Prunus persica Salt Overly Sensitive 2 (PpSOS2) in atsos2 mutant imparts salt tolerance in Arabidopsis. ACS Agricultural Science and Technology. 2(1):153-164. https://doi.org/10.1021/acsagscitech.1c00276.
DOI: https://doi.org/10.1021/acsagscitech.1c00276

Interpretive Summary: Soil salinity is one of the major environmental stresses that affect the growth and development of plants. Salt-tolerance in plants is a complex trait in which the exclusion of ions from root to soil is crucial. The exclusion of Na+ ions from the root cytoplasm is carried out by the members of the Salt Overly Sensitive (SOS) pathway. The SOS pathway consists of three members: SOS1, SOS2, and SOS3. The SOS2 gene has not been characterized in almond rootstocks. In this investigation, we have isolated and cloned the SOS2 gene from almond rootstock Nemaguard (PpSOS2) and transformed that into the Arabidopsis mutant (atsos2) to validate its functional role. The transgenic lines containing PpSOS2 were tolerant to high salt concentrations, produced long and dense lateral roots, and had low electrolyte leakage. These observations suggest that transgenic plants coped well with increased salt concentration by maintaining the integrity of the membranes. Further studies on PpSOS2 will help to gain a deeper understanding of its specific role in salt-tolerance in almonds. The information generated will be useful to geneticists to decipher individual components of the salt tolerance mechanism, which then can be utilized by almond breeders to breed salt-tolerant varieties.

Technical Abstract: Salinity is one of the main environmental stresses that negatively affect crop productivity. Almond trees are sensitive to salt stress; however, salinity-tolerant rootstocks can significantly enhance crop production under saline conditions. This work reports the functional complementation of the Prunus persica Salt Overly Sensitive 2 (PpSOS2) gene from the almond rootstock “Nemaguard” in the Arabidopsis thaliana atsos2 mutant. Two transgenic lines of PpSOS2 developed using constitutive (PpSOS2.OE3.5) and endogenous (PpSOS2NP.2.7) promoters showed significantly higher germination, survival rates, and dry weight than atsos2 under 90 mM NaCl treatment. The atsos2 mutant displayed the inhibition of primary and lateral roots under 50 mM NaCl. The root growth inhibition was restored by PpSOS2 complementation. Both transgenic lines showed a significant decrease in electrolyte leakage compared to atsos2 under 50 mM NaCl. The expression analysis of six K+-rectifying channel genes and a reactive oxygen species-specific gene revealed the differential expression of AtCHX14 and AtCHX13 genes in transgenic lines compared to atsos2 24 h after the 50 mM NaCl treatment. These observations suggest that PpSOS2 modulates and restores salt tolerance in atsos2. Also, in Prunus, the SOS pathway is conserved, suggesting that the exclusion of Na+ is an important component trait for salt tolerance.