The specific primers were designed based on the full-length sequence of 1-deoxy-D-xylulose-5-phosphate synthase (CoDXS) and 1-deoxy-D-xylulose-5-phosphate reductoisomerase (CoDXR) genes from Cassia obtusifia.The OFR sequences of CoDXS and CoDXR were cloned by PCR.Prokaryotic expression vectors of pTrc-CoDXS and pTrc-CoDXR were constructed and expressed in TOP10 containing plasmid PAC-BETA.The function of CoDXS and CoDXR genes were verified by the color change of TOP10.The expression levels of CoDXS and CoDXR genes in different tissues and six stress conditions were analyzed by fluorescent quantitative PCR.The results showed that the CoDXS gene contains a 2127 bp OFR and encodes a predicted protein of 708 amino acid.The CoDXR gene contains a 1416 bp OFR and encodes a predicted protein of 471 amino acid.The results of functional identification showed that TOP10 containing CoDXS and CoDXR genes appeared dark orange.Relative real-time PCR analysis indicated that CoDXS showed the highest transcript abundance in the flowers,moderate level in the stems,lower level in the seeds,and the lowest level in the roots.The CoDXR showed the highest transcript abundance in the leafs,moderate level in the flowers,lower level in the stems,and the lowest level in the seeds.Under salt stress:the expression level of CoDXS gene showed a downward trend,and the expression level of CoDXR gene fluctuated within a small range.Under ABA stress conditions:the expression level of CoDXS gene showed a downward and upward trend,and the expression level of CoDXR gene showed an upward trend.Under MeJA stress conditions:the expression levels of CoDXR and CoDXS genes showed a downward and upward trend.Under PEG6000 stress conditions:it had little effect on the expression level of CoDXS gene,and the expression level of CoDXR gene showed an upward trend.Under the heat stress conditions:the expression level of CoDXS gene showed a downward trend,and had little effect on the expression level CoDXR gene.Under cold stress conditions:the expression levels of CoDXS and CoDXR genes showed a downward trend.

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