Characterization of a stress-enhanced promoter from the grass halophyte, Spartina alterniflora L

Authors: SENGUPTA, SONALI - LSU Agcenter; PEHLIVAN, NECLA - LSU Agcenter; MANGU, VENKATA - LSU Agcenter; Rajasekaran, Kanniah - Rajah; BAISAKH, NIRANJAN - LSU Agcenter

Submitted to: Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2022
Publication Date: 12/15/2022
Citation: Sengupta, S., Pehlivan, N., Mangu, V., Rajasekaran, K., Baisakh, N. 2022. Characterization of a stress-enhanced promoter from the grass halophyte, Spartina alterniflora L. Biology. 11(12):1828. https://doi.org/10.3390/biology11121828.
DOI: https://doi.org/10.3390/biology11121828

Interpretive Summary: All plants get affected by stress due to pathogens and harsh environmental conditions. Stress-inducible gene expression in plants is often associated with high degree of susceptibility to drought which in turn affects the plants' resistance to microbial infection including toxin-producing fungal species. We studied the role of stress-inducible promoters (driving the expression of genes) isolated from a Louisiana coastal grass species in regulating molecular control of drought, dehydration, resistance to low temperature, salt and drought tolerance. Our research provides ample evidence that transgene expression under stress-inducible promoter is a better strategy for genetic manipulation of important crops such as cotton, peanut and corn which are susceptible to infection by toxin-producing fungi under adverse conditions.

Technical Abstract: Stress-inducible promoters are vital for desirable expression of genes, especially transcription factors, which could otherwise compromise growth and development when constitutively overexpressed in plants. Here, we report on characterization of the promoter region of a stress-responsive gene SaAsr1 from monocot halophyte cordgrass (Spartina alterniflora). Several cis-acting elements, such as ABRE (ABA-responsive element), DRE-CRT (dehydration responsive-element/C-Repeat), LTRE (low temperature-responsive element), ERE (ethylene-responsive element), LRE (light-responsive element), etc. contributed at varying degree to salt-, drought- and ABA-enhanced expression of gusA reporter gene in Arabidopsis thaliana under the full-length promoter, pAsr11875 and its deletion derivatives with assortment of cis-regulatory motifs. The smallest promoter pAsr1491 with three cis-acting elements (CCAAT box- heat responsive, LRE, and copper responsive element) conferred drought-enhanced expression of gusA; pAsr1755 (with a ABRE and DRE) presented highest expression in ABA and drought; and pAsr1994 with seven ABREs and two DREs conferred optimal induction of gusA, especially under drought and ABA. Arabidopsis transgenics expressing a known abiotic stress-responsive gene, SaADF2 (actin depolymerization factor 2) under both pAsr11875 and p35S promoters outperformed the wild type (WT) with enhanced drought and salt tolerance contributed by higher relative water content and membrane stability with no significant difference between pAsr11875:SaADF2 or p35S:SaADF2 lines. However, pAsr11875:SaADF2 lines produced healthy plants with well-developed siliques and robust shoot systems under salt stress and control compared to slightly stunted growth of the p35S:SaADF2 plants. This reestablished the evidence that transgene expression under stress-inducible promoter is a better strategy for genetic manipulation of crops.