Inoculation of Soil with Plant Growth Promoting Bacteria Producing 1-Aminocyclopropane-1-Carboxylate Deaminase or Expression of the Corresponding acdS Gene in Transgenic Plants Increases Salinity Tolerance in Camelina sativa

Abstract

Camelina sativa (camelina) is an oilseed crop touted for use on marginal lands; however, it is no more tolerant of soil salinity than traditional crops, such as canola. Plant growth-promoting bacteria (PGPB) that produce 1-aminocyclopropane-1-carboxylate deaminase (ACC deaminase) facilitate plant growth in the presence of abiotic stresses by reducing stress ethylene. Rhizospheric and endophytic PGPB and the corresponding acdS- mutants of the latter were examined for their ability to enhance tolerance to salt in camelina. Stimulation of growth and tolerance to salt was correlated with ACC deaminase production. Inoculation of soil with wild-type PGPB led to increased shoot length in the absence of salt, and increased seed production by approximately 30–50% under moderately saline conditions. The effect of ACC deaminase was further examined in transgenic camelina expressing a bacterial gene encoding ACC deaminase (acdS) under the regulation of the CaMV 35S promoter or the root-specific rolD promoter. Lines expressing acdS, in particular those using the rolD promoter, showed less decline in root length and weight, increased seed production, better seed quality and higher levels of seed oil production under salt stress. This study clearly demonstrates the potential benefit of using either PGPB that produce ACC deaminase or transgenic plants expressing the acdS gene under the control of a root-specific promoter to facilitate plant growth, seed production and seed quality on land that is not normally suitable for the majority of crops due to high salt content.

Plantibacter flavus, Curtobacterium herbarum, Paenibacillus taichungensis, and Rhizobium selenitireducens Endophytes Provide Host-Specific Growth Promotion of Arabidopsis thaliana, Basil, Lettuce, and Bok Choy Plants

“…The most notable of these are pathways for phytohormone production, as microbial production of auxins and cytokinins are common contributors to plant growth promotion (65-68) since auxins and cytokinins play important roles in stimulating plant growth and development throughout all cell types (69)(70)(71)(72). ACC deaminase benefits plant growth under stressful conditions, since ACC deaminase breaks down excess stress ethylene, which reduces general stress symptoms (73)(74)(75).…”

Fueling the future; plant genetic engineering for sustainable biodiesel production

“…The gene encoding 1-aminocyclopropane-1-carboxylate deaminase (acdS: ACC deaminase) which enhances abiotic tolerance in plants by reducing stress ethylene, was transferred to Camelina. The GM Camelina lines expressing acdS, showed higher root length and weight, seed production, as well as seed quality and seed oil content under salt stress compared with the wild type (Heydarian et al, 2016).…”

“…(Tang et al, 2011;Jha et al, 2013;Heydarian et al, 2016). Moreover, functionality of transcription factor JcCBF2 (a cold response transcription factor) and JcDREB (a putative AP2/EREBP domain of DREB subfamily) derived from Jatropha, in improving freezing tolerance has been confirmed by expression in Arabidopsis(Tang et al, 2011; Wang et al, 2015).…”

Ureide metabolism in plant-associated bacteria: purine plant-bacteria interactive scenarios under nitrogen deficiency

“…A breakthrough in breeding for salinity tolerance is the generation of salt-tolerant transgenic Camelina sativa expressing the Ps. putida UW4 acdS gene encoding the ACCD under the control of the root-specific promoter (rolD) (Heydarian et al 2016). It is interesting to speculate that the evolutionary drive for microbes to establish association with plants was to have access to the nutrient resources that plants provide and to maximize this new nutritional niche.…”