Cloning of a CHS gene of and its expression in response to soil water deficit and arbuscular mycorrhizal fungi.

Flavonoids are secondary metabolites widely found in plants with antioxidants, of which chalcone synthase (CHS) is a key enzyme required in flavonoid synthesis pathways. The objective of this study was to clone a gene from trifoliate orange () and analyze its biological information and partial functions. A PtCHS gene (NCBI accession: MZ350874) was cloned from the genome-wide of trifoliate orange, which has 1156 bp in length, encoding 391 amino acids, with a predicted protein relative molecular mass of 42640.19, a theoretical isoelectric point of 6.28, and a lipid coefficient of 89.82. The protein is stable, hydrophilic, and high sequence conservation (92.49% sequence homology with CHS gene of other species). was highly expressed in stems, leaves and flowers, but very low expression in roots and seeds. Soil water deficit could up-regulate expressions of in leaves. An arbuscular mycorrhizal fungus, , significantly increased plant biomass production, CHS activity, expressions of , and total flavonoid content in leaves and roots, independent of soil water status. Total flavonoids were significantly positively correlated with expression in leaves only and also positively with root mycorrhizal colonization. Such results provide insight into the important functions of in trifoliate orange.