High-level expression of sucrose inducible sweet potato sporamin gene promoter: beta-glucuronidase fusion gene in transgenic Nicotiana plumbaginifolia

摘要

We produced transgenic Nicotiana plumbaginifolia plants which contained Spo(min) (sporamin minimal promoter)-GUS fused chimeric gene constructs with 5 types of signal sequences, such as cytosol, apoplast, ER, vacuole and plastid, and analyzed the GUS expression patterns after sucrose treatment. Spo(min) induced extremely high GUS activities after 6% and 10% sucrose treatment, especially in leaves. The high GUS activities were observed in leaves of the Spo(min)-ER-GUS construct treated with 6% or 10% sucrose. These were over 200 times higher than those in leaves with the 35S promoter-ER-GUS construct. The 10% sucrose treatment significantly altered GUS activities in all Spo(min) and 35S promoter constructs compared with those in the 6% sucrose treatment; some increased and some decreased. GUS activities in 2 months old plants were almost the same as 8 months old plants, indicating that GUS expression driven by Spo(min) was stably maintained. Also, even when sucrose treatment was stopped, GUS gene expression by Spo(min) continued for 10 days.