Functional Characterization Of A Novel Chitinase Gene LcChi2 In Transgenic Maize

Chitinase universally exists in plants, animals and microorganisms, and it is encoded by different chitinase multigene family. Chitinase can degrade the cell wall of pathogenic fungal hosts, and suppress pathogenic fungus growth. So, Chintinase is thought to be a broad-spectrum enzyme related to fungi disease resistance and has been applied in the study of plant disease resistance for many years. Exogenous chitinase gene has been transferred into many plants, such as arabidopsis, tobacco, rice and wheat. And all of them showed significantly enhanced resistance to fungal disease. However, it is rarely reported that whether chitinase gene can enhance the ability of transgenic plants to abiotic stress.A new chitinase gene LcChi2 showed enhanced resistance to fungal disease and tolerance to saline-alkali, when it is over-expressed in the model plant tobacco in the previous study. To further demonstrate whether LcChi2 can shows the disease resistant and saline-alkaline tolerant dual function in maize which is an important crop, we constructed a bivalent gene plant expression vectors which both contain LcChi2 and herbicide screening marker gene Bar. Then, the bivalent genes vector was transferred into Hi II, via Agrobacterium-mediated transformation. The resulting transgenic maize was confirmed by PCR, Southern hybridization, RT-PCR and chitinase activity measurements, indicating that LcChi2 and Bar was integrated into the nuclear genome of maize and expressed effectively. The transgenic maize was artificially inoculated with the leaf blight and Curvularia leaf spot pathogens, showing higher resistance to the diseases. The results of laboratory and field saline-alkaline stress experiments of transgenic maize indicated that LcChi2 could improve the ability of transgenic plants against saline-alkaline stress. Meanwhile, the transgenic maize exhibited herbicide resistance suggesting that it not only has the function of disease resistance and saline-alkaline tolerance, but also has the herbicide resistance ability. In conclusion, LcChi2 could improve the ability of transgenic plants against diseases and saline-alkaline stress, and it will provide an important reference for the future development of new varieties of disease resistant and saline-alkaline tolerant crops.