Drought and UV Radiation Stress Tolerance in Rice Is Improved by Overaccumulation of Non-Enzymatic Antioxidant Flavonoids
Rahmatullah Jan,
Muhammad-Aaqil Khan,
Sajjad Asaf,
Lubna,
Muhammad Waqas,
Jae-Ryoung Park,
Saleem Asif,
Nari Kim,
In-Jung Lee,
Kyung-Min Kim
Affiliations
Rahmatullah Jan
Division of Plant Biosciences, Department of Applied Biosciences, College of Agriculture and Life Science, Kyungpook National University, 80 Dahak-ro, Buk-gu, Daegu 41566, Korea
Muhammad-Aaqil Khan
Division of Plant Biosciences, Department of Applied Biosciences, College of Agriculture and Life Science, Kyungpook National University, 80 Dahak-ro, Buk-gu, Daegu 41566, Korea
Sajjad Asaf
Natural and Medical Science Research Center, University of Nizwa, Nizwa 616, Oman
Lubna
Department of Botany, Garden Campus, Abdul Wali Khan University, Mardan 23200, Pakistan
Muhammad Waqas
Department of Agriculture Extension, Government of Khyber Pakhtunkhwa, Mardan 23200, Pakistan
Jae-Ryoung Park
Division of Plant Biosciences, Department of Applied Biosciences, College of Agriculture and Life Science, Kyungpook National University, 80 Dahak-ro, Buk-gu, Daegu 41566, Korea
Saleem Asif
Division of Plant Biosciences, Department of Applied Biosciences, College of Agriculture and Life Science, Kyungpook National University, 80 Dahak-ro, Buk-gu, Daegu 41566, Korea
Nari Kim
Division of Plant Biosciences, Department of Applied Biosciences, College of Agriculture and Life Science, Kyungpook National University, 80 Dahak-ro, Buk-gu, Daegu 41566, Korea
In-Jung Lee
Division of Plant Biosciences, Department of Applied Biosciences, College of Agriculture and Life Science, Kyungpook National University, 80 Dahak-ro, Buk-gu, Daegu 41566, Korea
Kyung-Min Kim
Division of Plant Biosciences, Department of Applied Biosciences, College of Agriculture and Life Science, Kyungpook National University, 80 Dahak-ro, Buk-gu, Daegu 41566, Korea
Drought and ultraviolet radiation (UV radiation) are the coexisting environmental factors that negatively affect plant growth and development via oxidative damage. Flavonoids are reactive, scavenging oxygen species (ROS) and UV radiation-absorbing compounds generated under stress conditions. We investigated the biosynthesis of kaempferol and quercetin in wild and flavanone 3-hydroxylase (F3H) overexpresser rice plants when drought and UV radiation stress were imposed individually and together. Phenotypic variation indicated that both kinds of stress highly reduced rice plant growth parameters in wild plants as compared to transgenic plants. When combined, the stressors adversely affected rice plant growth parameters more than when they were imposed individually. Overaccumulation of kaempferol and quercetin in transgenic plants demonstrated that both flavonoids were crucial for enhanced tolerance to such stresses. Oxidative activity assays showed that kaempferol and quercetin overaccumulation with strong non-enzymatic antioxidant activity mitigated the accumulation of ROS under drought and UV radiation stress. Lower contents of salicylic acid (SA) in transgenic plants indicated that flavonoid accumulation reduced stress, which led to the accumulation of low levels of SA. Transcriptional regulation of the dehydrin (DHN) and ultraviolet-B resistance 8 (UVR8) genes showed significant increases in transgenic plants compared to wild plants under stress. Taken together, these results confirm the usefulness of kaempferol and quercetin in enhancing tolerance to both drought and UV radiation stress.
