Cloning And Functions Of NAC Transcription Factor(SlNAC11) In Tomato(Lycopersicon Esculentum)

NAC(Petunia NAM, Arabidopsis ATAF1/2 and CUC2) transcription factors, which were found to participate in diverse processes, belong to a large plant-specific TF family. All of their proteins share a highly conserved N-terminus containing the DNA-binding NAC domain is approximately 150 amino acids in length and a variable C-terminus which were considered to be a regulatory region of transcription. As one of he largest plant-specific transcription factor families, NAC proteins play crucial roles in levelopment programs, leaf senescence, shoot apical meristem development, flower development, hormone signaling, formation of the secondary walls and resistance to stresses.In this study, we choosed wild type (WT) tomato AC++ as our research subject, cloned and studied a new member of NACs, NAC11. The main points and results are as follows:(1) we cloned the target gene, named it as SlNAC11, whose largest ORF (Open Reading Frame) codes a polypeptide chain contains 350 amino acids. Mutiple sequence aligment between SlNAC11 and known NAC proteins showed that the NAC domain of SINAC11 can be divided into five regions (A to E), and SlNAC11 was pretened to be well conserved in C and D regions; phylrgenetic tree analysis suggested that SlNAC11 had high similarity to RD26 and OsNAC6, it means that SlNAC11 may belong to the ATAF subfamily and be involved in resposing to stresses;(2) tissue-specific expression patterns of SlNAC11 were analyzed by using the real time PCR technique. The results showed that the gene expression level of SlNAC11 was declined along with the development of leaves (highest in young leaves and lowest in senescent leaves), suggesting that SlNAC11 may play roles in development programs of eaves and responsing to stresses in tomato;(3) we contrusted the RNAi vector of SlNAC11 (SINACll-RNAi vector) in accordance with the experimental principle and method, then obtained the trangenic tomato lines by transforming the SINAC11-RNAi vector into tomato AC++ which laid the foundation of further studying gene functions of SlNAC11;(4) the expression level of SINAC11 in WT under various hormone treatment(ABA, ACC, MeJA,GA3 and IAA) was detected by real time PCR, the results showed that the JANAC11 |expression of SINAC11 was induced by ABA, MeJA and GA3, indicating that SlN nay be involved in regulation processes of homones and related responses to stresses;(5) results of the expression level of SINAC11 in WT under various abiotic reatments (high/low temperature, dehydration and salt) detected by real time PCR showed that the expression of SINAC11 was induced by hgh/low temperature, lehydration and salt, indicating that SINAC11 may be involved in kinds of abiotic stresses;(6) results of the the seed germination rate of trasgenic T1 lines to salinity and the sensitivity of transgenic Tl seedlings to ABA and salinity showed that interferring the expression of SlNAC11 lead transgenic seeds more hypersusceptible and declined olerance to salinity, and then resulted in lower germination rate, whereas there was no iignificantly influence on seedlings; meanwhile, interferring the expression of SlNAC11 brought about less sensitive to exogenous ABA to transgenic seedlings compared to WT, suggesting that SINAC11 may be an ABA-dependent stress-inducible factor;(7) results of drought stress assay conducted on positively transgenic T1 lines and elated phisiological measures states that silencing the expression of SlNAC11 reduced rought-tolerant of transgenic tomato.To summary, results of the informatics showed that SINAC11 belongs to the ATAF subfamily; the expression level of SlNAC11 detected by qRT-PCR under hormones and ibiotics stimulate suggested that the expression of SlNAC11 can be induced by ABA、 MeJA and other environmental factors; results of related experiments conducted on the rasgenic T1 lines suggested that silencing the expression of SINAC11 in tomato confered the transgenic tomato (1) more sensitivity to salinity during seed germination stage, whereas no remarkabe differences were observed during the seedling stage, (2) less sensitivity to ABA, (3) lower resistance to drought.