Expression Analysis of Nudix Hydrolase Genes in Chrysanthemum lavandulifolium

Nudix hydrolases are associated with detoxification processes in plants under abiotic stress and regulate disease resistance signal transduction pathways. Investigating expression patterns and phyletic evolution of eight Nudix hydrolase gene family members in Chrysanthemum lavandulifolium will provide insights into detoxification pathways. In this study, full-length open reading frames of eight Nudix hydrolase genes (ClNUDX1-8) were obtained using a C. lavandulifolium expressed sequence tag (EST) database, EST splicing, and rapid-amplification of cDNA ends. Sequence similarity analysis of the eight ClNUDXs using MEGA4.0 software revealed that these genes belonged to seven subfamilies of the plant Nudix hydrolase gene family. Reverse transcription-polymerase chain reaction analysis demonstrated that five genes exhibited organ-specific expression; these included ClNUDX1, ClNUDX2, ClNUDX3, CINUDX7, and ClNUDX8. Among those, ClNUDX1, ClNUDX3, ClNUDX7, and ClNUDX8 were induced by salt, drought, heat, and cold stresses. ClNUDX2 was only influenced by salt and drought. Transcription levels of both ClNUDX1 and ClNUDX2 were also regulated by abscisic acid and salicylic acid. The promoter of ClNUDX1, CN1P, was cloned. Transient expression analysis indicated that CN1P was capable of driving expression of the GUS reporter gene. Thus, it was concluded that different members of Nudix hydrolase genes in C. lavandulifolium demonstrated varied expression patterns in response to different abiotic stresses. These findings further elucidated knowledge on the response mechanisms to abiotic stresses in C. lavandulifolium.