A Comprehensive Review on Understanding Drought Resilience Mechanisms in Sunflower (Helianthus Annuus L.)

Laraib Chouhdary

Department of Botany, University of Agriculture Faisalabad

Abstract

As an important oil crop and ornamental crop, sunflower (Helianthus annuus L.) displays moderate drought resistance which is crucial in maintaining yields in the face of water shortage due to climate change. This review explains the adaptations of sunflowers to drought stress which are physiological, biochemical and molecular. Physiologically, deep taproot systems form in sunflowers and dry moisture (up to 40 per cent) of the subsoil, and their leaves are folded downward to shorten the transpiration duration. Biochemical adaptation involves osmotic adjustment by storing proline and betaine and retention of turgor during drought. The amount of antioxidant systems (e.g. superoxide dismutase and ascorbate peroxidase) rises 1.5 to 2-fold to reduce the effects of reactive oxygen species (ROS). Transcriptomic analyses mediate the identification of differentially expressed genes (DEGs) of 2,589 genes in leaf, along with their transcriptional influences, such as deregulated osmolyte production and reactive oxygen species defenses (DREB2A, etc.). Genomic technologies which include genome-wide association, marker-assisted selection, and CRISPR/Cas9 are being applied to target root traits and water-use efficiency which makes the breeding cycles only six years. The ability to withstand stress with regard to water uptake and seed set has been provided by the wild Helianthus species, especially H. argophylus. Agronomic practices, such as drip irrigation and mulching, maximizing water-use and yield stability. Nevertheless, extreme drought conditions lower yield of achene by 3050 percent and oil level by 510 percent because the activity of the RuBisCO enzyme is impaired. Cropping techniques (e.g. drip irrigation, early planting) and CRISPR/Cas9 manipulation of Hahb4 are more resistant to drought. A combination of breeding, inoculation with microbes, and optimal control can maintain the productivity of sunflower in dry areas, which can be used to mitigate the problem of climate change.