Chloroplast Engineering of Salt Tolerance

Through plastid genome engineering, we have achieved agronomic transformation of many important crops, such as herbicide resistance, drought tolerance, salt tolerance, insect resistance, pathogen resistance, nitrogen fixation, nutrition, and cytoplasmic male sterility. Here, Lifeasible is committed to providing crops with reliable and economical chloroplast genetic engineering solutions to enhance the tolerance of crops to salt stress.

Introduction

Global agricultural productivity is affected by soil salinity, a serious abiotic stress. Crops are very sensitive to high concentrations of salinity in the soil, which can lead to ionic imbalances, hyperosmotic stress, oxidative damage and other subsequent disturbances. Salt levels, which are harmful to plant growth, affect much of the world's terrestrial areas and lead to food shortages. Therefore, increasing crop yields on poor lands including saline soils, is an absolute necessity to feed the world. Chloroplasts function through several important pathways in response to salt stress, such as thylakoid membrane organization, carbon dioxide (CO₂) assimilation, photorespiration, reactive oxygen species (ROS) scavenging, osmosis, and ion homeostasis, etc.

Fig. 1. The three main mechanisms of salinity tolerance in a crop plant. (Roy S J, et al., 2014)

Our Solutions

Complicated by the polygenic nature of salt tolerance, developing traits that contribute to salt tolerance is straightforward. Our engineers try to develop multiple candidate genes for transforming crops to improve salt tolerance. We currently offer the following solutions based on genes encoding chloroplast-localized proteins in response to salinity to improve crop-specific salt tolerance traits.

(1) Salinity-induced Multiple ROS Scavenging Pathways in Chloroplasts

We enhance the defense of crops against oxidative damage induced by salt stress through salinity-responsive genes encoding antioxidant enzymes/proteins, such as thioredoxin/peroxiredoxin (Trx/Prx), glutathione peroxidase (GPX), methionine sulfoxide reductase (MSR), etc.

(2) Thylakoid Membrane Organization and Photosynthesis

We improved salt tolerance by enhancing its photorespiration capacity by encoding a salinity-responsive gene for photosynthesis, such as glycerol 3-phosphate acyltransferase (GPAT), monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), redoxin (RUB), NADP+ dependent malate dehydrogenase (NADP-MDH), etc.

(3) Penetration and Ionic Homeostasis

We enhanced tolerance to salt stress through genes encoding osmoprotectants, including betaines, amino acids, non-reducing sugars and polyols, etc.

(4) ABA and Kinase Signaling Pathway

We enhanced tolerance to salt stress through genes encoding ABA and kinase signaling pathways, including ABA1, ABA4, NCED, MsK4, etc.

(5) Chloroplast Gene Expression and Protein Turnover

We enhance tolerance to salt stress by encoding our genes that encode chloroplast gene expression and protein turnover, including DEAD-box RNA helicases (RHs), RNA recognition motifs (RRMs), chloroplast translation elongation factors (EF-Tu), etc.

Attractive Advantages of Our Solutions

• We improve crop salt tolerance by combining multiple traits, including ion rejection, osmotic tolerance, and tissue tolerance.
• Several key pathways in the chloroplast response to salt have been developed.
• We focus on three aspects of enhancing salt tolerance, ion homeostasis, expression regulation and antioxidant protection.
• We have identified more than 53 salt-responsive genes.

Lifeasible's goal is to provide customers around the world with fully customized chloroplast engineered solutions for salt tolerance. Please contact us to discuss further details to ensure your next success.

References

1. Roy S J, Negrão S, Tester M. (2014) Salt resistant crop plants[J]. Current opinion in Biotechnology. 26: 115-124.
2. Suo J, Zhao Q, David L, et al. (2017) Salinity response in chloroplasts: insights from gene characterization[J]. International Journal of Molecular Sciences. 18(5): 1011.