Molecular Networking of Regulated Transcription Factors under Salt Stress in Wild Barley (H. spontaneum)

Rania M. Makki

¹Department of Biological Sciences, Faculty of Science, King Abdulaziz University (KAU), P.O. Box 80141, Jeddah 21589, Saudi Arabia

Corresponding Author E-mail : rmakki@kau.edu.sa

DOI : http://dx.doi.org/10.13005/bbra/2858

ABSTRACT: Salt stress is among environmental conditions that severely retards plant growth. Scope of this work is the detection of transcription factors that might participate in regulating salt-stressed genes in wild barley (Hordeum spontaneum). Expression profiles of important types of transcription factors (TFs) were displayed. They include WRKY and MYB, that were regulated under salt stress. WRKY19 and NAC96 are known to induce stress tolerance through activation of DREB2A (or Ap2-ERF). NAC96 concordantly upregulated with DREB2A gene under salt stress in H. spontaneum, a possible crosstalking to compensate the negative performance of WRKY19 gene. P5CS, for proline accumulation, is also known to be driven by ERF1 and genes encoding these proteins concordantly upregulated in H. spontaneum under salt stress supporting NAC96/ERF1/P5CS crosstalking towards proline accumulation under stress. Genes encoding enzymes participating in the last steps of glucose, sucrose and maltose biosyntheses concordantly upregulated with WRKY11 that is also involved in driving genes encoding free proline. B-box zinc finger protein 21 (BZF21) concordantly expressed with genes encoding catalase and SAUR40 indicating that BZF21 gene might drive expression of the two genes under salt stress. Upregulated WRKY41 and WRKY46 under salt stress in wild barley are known to exhibit enhanced stomatal closure, reactive oxygen species (ROS) scavenging, lateral roots development via regulation of ABA signaling and auxin homeostasis. The latter action is governed by GH3.8 gene that was upregulated in wild barley. MYB30 is known for being SUMOylated by SIZ1. In the present study, MYB30, MYB44 and MYB3R-2 genes were concordantly expressed with SIZ2 gene supporting their crosstalking under salt stress in H. spontaneum. Based on the regulation of WRKY19 and MYB30 genes under salt stress in H. spontaneum, we suggest that the first is a positive activator, while the second is a negative activator of FT gene that drives early flowing in plants. MYB44 that promotes stomatal closure under stress can also serve in conferring tolerance to abiotic stresses in wild barley. Several other downregulated genes under salt stress, e.g., MYB1, MYB20 and MYB73, were previously reported to negatively regulate abiotic stress tolerance in plants. We suggest that WRKY gene family participates in salt stress responses in leaves of H. spontaneum following approaches different from those of other plants. Regulation of MYB gene family is almost similar to that of other plant species under salt stress. In conclusion, the present study addresses some of the regulatory frameworks driving expression of salt-related genes in H. spontaneum that can be utilized in plant, e,g, cereals, breeding programs to improve their salt stress tolerance.

KEYWORDS: DREB; FT; GH3; MYB; NAC; SAUR, SIZ; WRKY

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