Patterns of domestication in upland cotton (Gossypium hirsutum): a perspective from multielement stoichiometry

Upland cotton (Gossypium hirsutum) is one of the most important cash crops in the world, but few studies have investigated its chemical and physiological changes during domestication, especially changes in chemical element stoichiometry. We investigated the concentrations of 15 chemical elements (carbon, nitrogen, calcium, potassium, sulfur, phosphorus, magnesium, iron, silicon, manganese, boron, zinc, nickel, copper, and molybdenum) in the leaves of 41 genotypes of semiwild and domesticated upland cotton. Principal component analysis, network analysis and domestication effect analysis were used to explore the changes in multielement stoichiometry during the domestication of upland cotton. Analysis of the multielement network indicated that calcium became a more important element after domestication. Across the studied genotypes, the concentrations of carbon and phosphorus decreased after domestication, whereas the concentrations of calcium, magnesium and zinc increased. These alterations resulted in significant domestication effects on some elemental ratios. Combined with changes in plant aboveground biomass, a genetic dilution effect of phosphorus was found. We proposed and tested the "elemental domestication effect" (EDE) in upland cotton (the higher the concentration of elements, the easier it is to be changed during domestication), which may provide new directions for potential crop breeding. We suggest further increasing the calcium, magnesium, and zinc concentrations to enhance the potential for cotton yield and quality, and to reverse the continuous decrease in phosphorus concentration through biological fortification.