Cotton GhHyPRP3 encoding a hybrid proline-rich protein is stress inducible and its overexpression in Arabidopsis enhances germination under cold temperature and high salinity stress conditions

Abstract

In this study, the cDNA coding for a hybrid proline-rich protein (HyPRP) was isolated from cotton cDNA libraries and designated GhHyPRP3. Analysis of the deduced amino acid sequence revealed that it contained an N-terminal signal peptide, a central proline-rich domain, and a C-terminal cysteine-rich domain highly homologous to other hybrid proline-rich group B proteins. RNA gel blot analysis showed that GhHyPRP3 mRNA was most abundant in petals and 10 DPA ovules indicating that expression of GhHyPRP3 was petal-preferential and ovule developmentally regulated. In addition, GhHyPRP3 transcription in roots was up-regulated by salt stress, cold stress, and osmotic stress, but down-regulated by GA3. A promoter-GUS reporter revealed that the GhHyPRP3 promoter directed gene expression in root–shoot junction, roots, and petals of transgenic Arabidopsis plants. Subcellular localization results showed that GhHyPRP3 was localized to the plasma membrane. Transgenic lines overexpressing GhHyPRP3 had a higher germination rate under cold temperature and high salinity stress conditions compared with wild type. Overall, GhHyPRP3 may function in flower and ovule development and participate in the defense responses to low temperature and salt stress.