SOM encodes a nucleus-localized CCCH-type zinc finger protein and negatively regulates seed germination in Arabidopsis thaliana. We have previously demonstrated that ectopic expression of Sl ABI3, an important transcription factor in abscisic acid（ABA） signaling pathway, resulted in alteration of Sl SOM expression patterns in both leaf and seed of tomato. In this study, we aimed to elucidate the function of tomato Sl SOM in regarding to seed germination and seedling development. Here, we constructed Sl SOM over-expression vector p BI121-SOM driven by Ca MV 35 S promoter, and the recombinant plasmid was incorporated into wild-type tomato by the method of Agrobacterium tumefaciens-mediated transformation. The result showed that over-expression of Sl SOM conferred enhanced responses to exogenous ABA application during seed germination and seedling development. In addition, ectopic expression of Sl SOM resulted in the alteration of expression level of ABA/GA（gibberellins） metabolic genes, such as Sl ABA1, Sl CYP707A1, Sl GA3ox2, and Sl GA2ox4, in both leaf and seed. The ABA anabolic gene Sl ABA1 and the GA catabolic gene Sl GA2ox4 were up-regulated while the ABA catabolic gene Sl CYP707A1 and the GA anabolic gene Sl GA3ox2 were down-regulated. Compared to wild type, the expression level of Sl ABI5 was increased by about 40–50% in transgenic seeds while adding exogenous ABA treatment. These results support the notion that Sl SOM inhibits seed germination by regulating ABA/GA metabolic genes and Sl ABI5 expression in Solanum lycopersicum.
SUN Xiao-chunGAO Yong-fengZHANG NingLI Hui-rongYANG Shu-zhangLIU Yong-sheng
The aldehyde dehydrogenase （ALDH） superfamily of NAD（P）-dependent enzymes, in general, oxidize a wide range of endogenous and exogenous aliphatic and aromatic aldehydes to their corresponding carboxylic acids and play an essential role in detoxification of reactive oxygen species （ROS） accumulated under the stressed conditions. In order to identify genes required for the stresses responses in the grass crop Oryza sativa, a homologue of ALDH gene （OsALDH22） was isolated and characterized. OsALDH22 is conserved in eukaryotes, shares high homology with the orthologs from aldehyde dehydrogenase subfamily ALDH22. The OsALDH22 encodes a protein of 597 amino acids that in plants exhibit high identity with the orthologs from Zea mays, Sorghum bicolor, Hordeum vulgare and Arabidopsis thaliana, respectively, and the conserved amino acid characteristics for ALDHs are present, including the possible NAD~ binding site （F-V-G-S- P-G-V-G）, the catalytic site （V-T-L-E-L-G-G-K） and the Cys active site. Semi-quantitative PCR and real-time PCR analysis indicates that OsALDH22 is expressed differentially in different tissues. Various elevated levels of OsALDH22 expression have been detected when the seedlings exposed to abiotic stresses including dehydration, high salinity and abscisic acid （ABA）. Transgenic rice plants overexpressing OsALDH22 show elevated stresses tolerance. On the contrary, down- 0 regulation of OsALDH22 in the RNA interference （RNAi） repression transgenic lines manifests declined stresses tolerance.
YANG Sheng-huiNIU Xiang-liLUO DiCHEN Chang-dongYU XuTANG WeiLU Bao-rongLIU Yong-sheng
