Effect of irrigation regimes on starch biosynthesis pathway, cotton (Gossypium hirsutum) yield and in silico analysis of ADP-glucose-pyrophosphorylase

This research was conducted to evaluate the impact of different irrigation on starch biosynthesis pathway with emphasis on cotton yield. Experiments were conducted in split-plot factorial design. Significant differences were observed in irrigation levels. Starch and alpha-amylase activity increased for seeds rainfed source under 100%field-capacity irrigation. Protein increased in seed sources that were grown in 33 and 66% water-need irrigated 100%field-capacity in double water stress exposure. Although rainfed seeds had an early harvest, highest total yield was observed in seed sources that were grown in exposure to 33%field-capacity which irrigated 100%field-capacity. To identify genes involved in starch biosynthesis, cotton alpha-amylase and ADP-glucose pyrophosphorylase were studied in silico. The alpha-amylase protein encoded 409 amino acids with a molecular weight of 46,790 Dalton. Alpha-amylase and ADP-glucose-pyrophosphorylase proteins belonged to the glycosyl hydrolase and transferase family, respectively. Phylogenetic analysis revealed that cotton sequences were separated along with co-family plants in the Malvaceae family. Biochemical responses observed in reduced glucose and protein and to a lesser extent starch as the level of water stress increased. Seeds exposed to double water stress had less starch than triple stress exposure. The sowing of seeds in water shortage continually resulted in low yields. Seeds obtained from 66%field-capacity irrigation had less starch, stomata density and more protein. Higher levels of protein and glucose were present in seeds exposed to double stress as compared to triple stress. In areas with limited water resources, it is recommended that cotton seeds be propagated under irrigation under 66%field-capacity, which have adequate carbohydrate resources and produce better yields.