Functional Analysis Of TfⅢa-Type Zinc Finger Proteins ZFP179and ZFP182from Rice (Oryza Sativa L.)

Rice (Oryza sativa L.) is not only one of the most important food crops in the world, but also a model plant for molecular research in monocots. Plant growth and crop productivity are largely affected by environmental stress such as drought, high salinity and low temperature. To date, many stress-related genes have been isolated and characterized from various plant species. These genes may encode products either directly protecting plants cells from abiotic stresses or regulating expression of other genes to enhance plant tolerance to abiotic stresses. Our research focused on two stress responsive TFIIIA type zinc finger proteins ZFP179and ZFP182from rice. The main results were described as follows:The real-time PCR analysis showed that ZFP179was constitutively expressed in leaves, culms, roots and immature and flowering spikes of rice at the adult stage with the highest expression amount in immature spikes, and markedly induced in the seedlings by NaCl, PEG6000, cold and ABA treatments. Yeast one hybrid analysis showed that ZFP179exhibited trans-activation activity in yeast. Transgenic rice plants overexpressing ZFP179showed higher tolerance to high-salt stress, and more sensitivity to exogenous ABA treatment. It was found that transgenic plants increased contents of free proline and soluble sugars after NaCl treatment, and elevated expression of OsDREB2A and some other stress-related genes. It was also found that overexpression of ZFP179enhanced the reactive oxygen species scavenging ability under salt stress and increased the tolerance of rice seedlings to oxidative stress. These results suggested that ZFP179plays a crucial role in plant response to salt stress, and is useful in developing transgenic crops with enhanced tolerance to salt stress.In order to analyze whether ZFP182, a TFIIIA-type zinc finger protein involved in abiotic stress, has the trans-activation activity, the coding region of ZFP182and its two deletion mutants were fused in frame to yeast GAL4binding domain vector and transformed into yeast strain AH109respectively. The results indicated that ZFP182exhibits trans-activation activity, and the C-terminal region enriched in acidic acids was responsible for the transactivation activity. Through a yeast two-hybrid system with ZFP182N as a bait, a cold-treatment rice cDNA library were screened. It was identified that23different proteins Z182IP1～Z182IP23might be interacted with ZFP182. Through BLAST algorithm search in NCBI it was found that the Z182IP1might encode a haloacid dehalogenase-like protein, Z182IP2a AMP-dependent synthetase or ligase protein, Z182IP3a dirigent-like protein, Z182IP4and Z182IP5chloroplast post-illumination chlorophyll fluorescence increase protein, Z182IP6a raffinose synthase or seed imbibition protein, Z182IP7a ubiquitin extension protein, Z182IP8, Z182IP9and Z182IP10ribosomal proteins, Z182IP11a thylakoid formation, ZI82IPI2a DnaJ chaperone C-terminal domain-containing protein, Z182IP13a C3HC4-type zinc finger protein, Z182IP14a metallothionein-like protein, Z182IP15a ATP-dependent helicase, but other eight accessions including Z182IPs, Z182IP16～Z182IP23without the known functional groups. The Z182IP7was selected for further analyzing the interaction with ZFP182through the BiFC and in vitro pull-down assay. It was found that ZFP182can interact with Z182IP7either in vitro or in vivo.