A novel plant annexin, CkANN, was isolated from Cynanchum komarovii. Sequence analysis showed that CkANN contained four conserved exdonexin fold regions, a putative peroxidase heme binding motif and two S3 clusters. Real-time PCR analysis indicated that the CkANN mRNA was abundant in leaf, flower, root and stem and that its level is highest in leaf and flower. The transcription level of CkANN was increased significantly following stress by salicylic acid (SA), methyl jasmonate (MeJA), abscisic acid (ABA), NaCl, PEG 6000 (polyethylene glycol) and H2O2. Over-expression of CkANN in transgenic cotton caused a significant increase in tolerance to drought and led to higher levels of proline and soluble carbohydrates compared to wild-type (WT) plants. In response to drought, the transgenic plants also displayed higher total chlorophyll levels and reduced accumulation of thiobarbituric acid-reactive substances (TBARS) compared to WT plants. Furthermore, the transgenic cotton showed enhanced resistance to Fusarium oxysporum via increased total peroxidase activity and induction of the expression of some pathogenesis-related proteins. In conclusion, this study has demonstrated that C. komarovii CkANN is involved in drought tolerance and disease resistance and therefore may contribute significantly to the development of drought- or disease-resistant crops.

UDP-glucose pyrophosphorylase is an important regulatory enzyme for the development of plants and a critical enzyme in synthesis of glycogen. Here, we reported the cloning of a full-length UGP cDNA from cotton, named GhUGP. Real-time PCR analysis indicated the GhUGP expression in root, stem, leaf and flower of cotton, with a higher level in flower and root. The transcription level of GhUGP depended on sucrose and light in short time and increased under low temperature, but decreased in O2 deficiency. Interestingly, the expression of GhUGP was significantly up-regulated after ethylene induction in cotton ovules. The over-expression of the GhUGP in Arabidopsis showed discrepant phenotype: increase in height and growth rate when compared with control lines. What is more, the transgenic Arabidopsis had increased contents of soluble sugars, starch and cellulose, but not in lignin content. Collectively, these results indicate that cotton UGPase participates in sucrose/polysaccharides metabolism and cell wall biosynthesis and provide theoretical deduction supporting GhUGP as a good candidate gene for improving the development of cotton fibers cell.