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Sarbesh D. Dangol, PhD Agricultural Genetic Engineering
Transcriptional and post-transcriptional gene
regulation during abiotic & biotic stresses in plants.
By Sarbesh D. DangolNigde, Turkey.
December 10, 2015.12/10/2015
Sarbesh D. Dangol, PhD Agricultural Genetic Engineering
Biotic/Abiotic stresses in plants
Stresses seriously reduce plant productivity.
Induces molecular events for cellular adaptation.
Involves transcription factors, kinase cascades, and reactive oxygen species (ROS).
Crosstalk enhances plant’s resistance against pathogens.
12/10/2015
Sarbesh D. Dangol, PhD Agricultural Genetic Engineering
Abiotic stress can induce biotic tolerance in plants and vice-versa
• Timely perception of stress.• Cross-tolerance: multiple stress cause plants to defend
themselves facing one stress and makes more resistant to other stresses.
• On drought stress, reduced infection of tomato by Botrytis cinerea and Oidium neolycopersici.
• Ozone exposure can induce resistance to virulent Pseudomonas syringae strains in Arabidopsis.
• Pathogenic wounding increases salt tolerance in tomato.
12/10/2015
Sarbesh D. Dangol, PhD Agricultural Genetic Engineering
Biotic/Abiotic stresses in plants
• Callose accumulation, changes in ions fluxes, ROS, and phytohormones are induced.
• Results in signal transduction that triggers metabolic reprogramming towards defense.
12/10/2015
Sarbesh D. Dangol, PhD Agricultural Genetic Engineering
Reactive Oxygen Species (ROS)
• The production of ROS is fine-modulated by the plant to avoid tissue damage.
• While high levels of ROS lead to cell death, lower levels are mostly responsible to regulate the plant’s stress responses.
• ROS might attenuate the oxidative stress caused by abiotic stress.
12/10/2015
Sarbesh D. Dangol, PhD Agricultural Genetic Engineering
MAPK cascades
• MAPK pathways activated by pathogen attack. • Mediated by SA/ ABA, and the resulting
expression of PR genes induces defense reactions.
12/10/2015
Sarbesh D. Dangol, PhD Agricultural Genetic Engineering
Abscisic acid (ABA)• Higher levels of ABA after Pst DC 3000 infection. • Suppression of other defense responses.
• Positive effect of ABA on biotic and abiotic stress resistance.
• Controversial molecule -- “good to bad”
depending on environmental conditions.12/10/2015
Sarbesh D. Dangol, PhD Agricultural Genetic Engineering
Transcription Factors and Molecular Responses in Cross-Tolerance
• Specific phytohormones (ABA, SA, JA, and Ethylene) mediate activity of PR genes.
• ABA and JA induces BOS1 gene and gives resistance against osmotic stress and necrotrophic pathogens.
• bos1 mutant plants are more susceptible to both stresses.
12/10/2015
Sarbesh D. Dangol, PhD Agricultural Genetic Engineering
PR genes
• PR genes are induced on plant’s exposure to abiotic stress ensuring disease resistance.
• Over-expression of TFs confronted with cold stress and infection activates cold-responsive PR genes.
• Upregulation of TFs after exposure to abiotic stress leads to an accumulation of PR proteins.
• CBF, DREB and NAC are TFs that confer tolerance under abiotic stresses.
12/10/2015
Sarbesh D. Dangol, PhD Agricultural Genetic Engineering
12/10/2015
PR genes upregulation during stresses
Sarbesh D. Dangol, PhD Agricultural Genetic Engineering
12/10/2015
Cross-signaling
Sarbesh D. Dangol, PhD Agricultural Genetic Engineering
12/10/2015
12/10/2015 Sarbesh D. Dangol, PhD Agricultural Genetic Engineering
TranscriptionalRegulation During abiotic stress
Central dogma
12/10/2015Sarbesh D. Dangol, PhD Agricultural
Genetic Engineering
12/10/2015Sarbesh D. Dangol, PhD Agricultural
Genetic Engineering
Post-transcriptionalregulation during abiotic stress
Sarbesh D. Dangol, PhD Agricultural Genetic Engineering
12/10/2015
Post-transcriptional regulation
Sarbesh D. Dangol, PhD Agricultural Genetic Engineering
12/10/2015
Post-transcriptional regulation during Geminivirus infection
Sarbesh D. Dangol, PhD Agricultural Genetic Engineering
12/10/2015
Geminivirus tries to antagonize plants’ stress response
12/10/2015
Sarbesh D. Dangol, PhD Agricultural Genetic
Engineering
Post transcriptional regulation during Agrobacterium infection
Sarbesh D. Dangol, PhD Agricultural Genetic Engineering
Thank you. 12/10/2015