Ectopic Expression of Sweet Potato Cysteine Protease SPCP3 Alters
Phenotypic Traits and Enhances Drought Stress Sensitivity in
Transgenic Arabidopsis Plants
Hsien-Jung Chen • Yi-Jing Tsai • Che-Yu Shen •Ting-No Tsai • Guan-Jhong Huang • Yaw-Huei Lin
Abstract In this report sweet potato cysteine protease SPCP3 cDNAs, with or without the corresponding granulin-like domain, were overexpressed in transgenic Arabidopsis plants. Transgenic Arabidopsis plants with ectopic expression of full-length SPCP3 exhibited slight promotion of earlier floral transition from vegetative to reproductive growth and a higher percentage of yellowing siliques per plant. Transgenic progeny seeds showed similar patterns of germination rates and germination curves but lower germination percentages compared to those of wild-type control seeds. During drought treatment, photochemical Fv/Fm values and relative water content of transgenic plants were significantly reduced compared to those of wild-type controls. Transgenic Arabidopsis plants with ectopic expression of sweet potato SPCP3 with or without the corresponding C-terminal granulin-like domain exhibited similar drought-stress sensitivity patterns. Drought stress also enhanced SPCP3 gene expression, photochemical Fv/Fm reduction, and wilting in sweet potato detached leaves. Based on these data, we conclude that sweet potato granulin-containing cysteine protease SPCP3 is a functional gene, and its ectopic expression alters phenotypic traits and enhances drought-stress sensitivity in transgenic Arabidopsis plants. The presence of the C-terminal granulin-like domain has no significant influence on SPCP3-mediated drought-stress sensitivity in transgenic
Arabidopsis plants.
Keywords Cysteine protease SPCP3 _ Drought _ Leaf senescence _ Sweet potato _ Transgenic Arabidopsis
