Sweet potato gene IbSAP15 enhances salinity tolerance of Arabidopsis thaliana
【摘要】：The IbSAP15 gene is a member of the sweet potato stress-associated protein gene family. It is special because it has two AN1 domains and no A20 domain. We conducted a preliminary study on the function of the IbSAP15 gene. p35 S::IbSAP15 was transformed into wild type Arabidopsis Col-0 by Agrobacterium-mediated transformation method. We tested the expresssion level of Ib SAP15 gene in the transgenic lines by real time PCR, and selected the L4 with higher expression level and L6 with lower expression level to further study. We investigated the responses of L4 and L6 to salt stress at three stages, i.e., seed germination, seedling growth, as well as mature plants. We also examined the physiological and biochemical changes in the leaves of L4 and L6 plants under salt stress. The main results are as follows: Seeds of p35 S::IbSAP15-L4, L6 and Col-0 were placed on MS medium containing 0, 50, 100, 150, or 200 mM NaCl, and the germination was observed. The results showed that the germination rates of L4, L6 and Col-0 seeds on media containing 0 mM NaCl were nearly 100 %, The germination rates of L4 and L6 on the media containing 50 mM to 200 mM NaCl was higher than those of Col-0. The germination rate of L4 was 43.75%, L6 was 33.75% and Col-0 was only 17.5% on the media containing 150 mM NaCl.(2) 3-day-old seedlings of L4, L6, and Col-0 were transferred to MS medium containing 0, 50, 100, 150 or 200 mM NaCl, and cultured for 8 d before the root length was measured. The results showed that the roots of L4 and L6 were longer than Col-0 on the media containing 0 to 150 mM NaCl. The root length of Col-0 was 35.2 mm, L4 was 42.2 mm, and L6 was 39.8 mm on the media containing 100 mM NaCl. The fresh weight of the transgenic Arabidopsis thaliana containing 0 to 150 mM NaCl media was heavier than Col-0. For example, the fresh weight of L4 was 18 mg, and L6 was 16.3 mg while Col-0 was 9.6 mg on the media containing 150 mM NaCl.(3) The survival rates of L4 and L6 were both 100%, while that of Col-0 was only 15% after 3-weekold L4, L6 and Col-0 was watered with liquid MS containing 300 mM NaCl for 15 d.(4) Physiological and biochemical indexes were tested after 3-week-old L4, L6 and Col-0 were treated with 200 mM NaCl for 3 days. The results showed that the content of chlorophyll, soluble sugar, Proline, and the activity of SOD and APX in L4 and L6 was higher than those of Col-0, while the MDA content is the opposite. The above results indicate that overexpression IbSAP15 gene in Arabidopsis thaliana plants can increase their salinity tolerance. It suggests that the Ib SAP15 gene is expected to improve the salinity tolerance of sweet potato, and to make sweet potato more suitable for planting in saline-alkali land and solving the contradiction between it and other crops in competing for land.