Transformation and Functional Analysis of Antisense Ethylene Receptor LeETR2 Gene in Tomato
Zhang Mingfang1 Xiang Qingning1 Ying Tiejin2 ** Yang Huqing2 Zheng Tiesong 3 Du Rongmao2
(1.College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310029,China; 2. College of Agricultural Engineering and Food Science, Zhejiang University, Hangzhou 310029,China; 3. College of Women, Nanjing Normal University, Nanjing 210095,China)
Abstract：Abstract： An antisense ethylene receptor gene LeETR2 was introduced into tomato (Lycopersicon esculentum ) through Agrobacberium tumefaciens -mediated method. Plantlets were regenerated in vitro by resistance selection on MS medium containing various concentrations of kanamycin. Approximately 73.5% of calli and 38.5% of leaves from plantlets exhibited intense blue color reaction by histochemical GUS assays. By PCR-aided assays, transformed plants displayed 362 bp (antisense LeEtr2 gene)and 500 bp(NPTⅡ) amplification products, however, they were not detected in non-transformed controls. Furthermore, Southern hybridization of DNA from PCR-positive transformants with the NPTⅡ probe indicated that the inserted gene was single copied in genome, by which it was further confirmed that the antisense LeETR2 gene was transferred into tomato. The transformants in tested lines showed delayed abscission, less elongated internodes(6±1.5) cm in length for transgenic plants and (8±1.58) cm for control, and out-growed axillary buds. The endogenous ethylene levels in fruits at day 3 after breaker in transgenic lines 1~5 were 155.58%, 166.96%, 251.76%, 441.07% and 100.89% of those in the controls, respectively. It is still ambiguous that how ethylene interacts with other hormones, such as auxin, abscisic acid and cytokinin in regulation of plant development through signal pathways. Nevertheless, the ethylene receptor LeETR2 might play a negative regulatory role in the signal transduction, and possibly involve other hormones in the control of plant development. It is essential to make clear how the antisense LeETR2 gene acts at transcriptional or translational level in the regulation of ethylene receptor LeETR2 gene, and whether it has regulatory side-effect on ethylene receptor LeETR1 gene due to their high sequence homologies.
