Cloning And Functional Characterization Of Stress-Related Transcription Factors In Maize

Maize is the most important cereal crop species, and is grown throughout a wide range of climates.By2050demand for maize will double in the developing world. The growing world population togetherwith the lack of expansion, or even reduction, of available arable lands, as well as the constraints ofabiotic stresses on yield potential, implies the importance of identifying genes involved in stressresponse and developmental pathway. In this study, I have cloned fifteen maize-specific transcriptionfactors, which the similarity in AA amino acid sequence share less than50%than rice and Arabidopsisthaliana. They belong to the ERF, C2H2, C3H, bZIP and bHLH five transcription families,respectively. Studies have shown that these types of transcription factors are widely involved in theprocess of plant growth, development and stress response. To further investigating their possiblebiological function of the transcription factors which are value for research and agriculture application,the work primarily analyzed the function of these transcription factors through, subcellular localization,expression level in response to abiotic stresses and hormones by real-time quantitative PCR, yeasttranscription activation analysis, and transgenic arabidopsis which were generated to study the effect ofoverexpression of target TFs on the process of development and response to stresses in arabidopsisthaliana.The major results are as follows:1) Through the Gateway system, fifteen transcription factors (ERF-1, ERF-3, ERF-5, ERF-7,ERF-8, C2H2-1, C2H2-3, C2H2-9, C2H2-11, C2H2-12, C3H-4, bZIP-1, bHLH-1, bHLH-4, bHLH-6)were cloned, and the result of subcellular localization showed that they were all located in the nucleus.2) Preliminary function analysis on the eight genes (ERF-7, ERF-8, C2H2, C2H2-3, bHLH-4,bHLH-6, C3H-4, bzip-1). The expression levels of these genes are induced by several abiotic stressesand hormones, which indicate that they are probably involved in the process of related signaltransduction. Transcription activation assay showed that only the ERF-8had trans-activation activity inyeast.3) According to root elongation experiment, ratio of leaf water loss experiment and droughtsurvival experiment, we found that compared with wild-type, root length of the overexpression C2H2-1transgnic arabidopsis is shorter, the ratio of leaf water loss is higher, and drought tolerance is weeker.They indicate that C2H2-1is a negative regulator involved in plant response to various abiotic stresses.4) The overexpression bHLH-4transgenic arabidopsis are dwarf, low fertility. The time ofbolting and flowering are advanced, and the branch number of flower stems is increased. Besides those,stems are thinner, the numer and of length-width ratio of blades are also increased. Leaves and pods aretwisted, and grain weight reducd a lot. These phenotypes above indicate that bHLH-4plays an importantrole in the process of seed germination, leaf and stem development, reproductive development.These results lay foundation for further study of molecular mechanism of plant growth,development and stress response. My work is benificial to the theoretical basis and genetic resources for molecular breeding which improve crop yield and enhance tolerance to stresses by transgenictechnology.