基于H2O2信号调控高氧气调包装（HO-MAP）鲜切菜心木质化的研究

Chinese cabbage is one of major vegetables in southern China, with special characteristics. The lignification of Chinese cabbage has seriously affected its eating quality. The preliminary study has showed that, compared with air packaging (AP) as control, the lignification of fresh-cut Chinese cabbage was inhibited by high oxygen modified atmosphere packaging (HO-MAP) and, the activities of key enzymes (PAL, 4-CL, CAD, POD) of lignin biosynthesis and, the level of H2O2 have been depressed. Howerever, the inhibition mechanism of lignification was completely unclear hitherto. Therefore, in this project, the fresh-cut Chinese cabbage treated by HO-MAP and AP and, the tissue-cultured Chinese cabbage treated by O2 and H2O2 (untreated ones as control) will be taken as the object of research. The study will involve the analysis for the content changes of lignin, intermediates of lignin synthesis, the levels of H2O2 and Ca2+, and pH values. In addition, real-time fluorescence quantitative RT-PCR (qRT-PCR) and Western blot will be employed to analyse the differential transcriptional and translational expressions of relevant enzymes' genes, such as the enzymes' genes invloved in the production and elimination of H2O2 and, the kinase genes in regulating the above enzymes; the key enzymes' genes in synthesis of lignin, such as PAL, 4-CL, C4H, CCR, CAD, POD and etc. Moreover, combined with the analysis of correlation of the physiological and biochemical parameters and the differential transcriptional and translational expressions, the regulating pathways of H2O2 level and lignin synthesis affected by H2O2 will be determined. The research will supply theoretical guidance for developing relevant fresh-keeping technique of fresh-cut Chinese cabbage.

菜心为南方特色蔬菜，其木质化的问题严重影响食用品质。前期研究表明，以空气包装（AP）作对照，HO-MAP 能够抑制鲜切菜心木质化及其合成关键酶（PAL、4-CL、CAD、POD）的活性和H2O2的水平，但是调控机理不明。因此本项目以HO-MAP和AP鲜切菜心、组培菜心（用H2O2和O2处理，不处理作对照）为研究对象，分析木质素及其合成中间产物含量、H2O2和Ca2+水平、pH值，运用qRT-PCR、Western blot技术，研究H2O2产生/清除相关酶及其调控激酶基因、木质素合成关键酶基因在转录和蛋白质水平表达的规律，并分析以上生理生化特性和基因表达特性之间的相关关系，明确HO-MAP 鲜切菜心中调控H2O2水平的途径，并揭示H2O2调控木质素合成的机制，为开发抑制鲜切菜心木质化的保鲜技术提供理论支持。

高氧包装能够抑制贮藏后期菜心中H2O2的产生，抑制贮藏后期呼吸速率，显著抑制相关关键酶活性，从而抑制菜心的木质化程度，较好维持菜心的营养品质。高氧包装菜心抑制了菜心的应激反应、防御反应、细胞壁组织或生物合成途径在转录水平的表达，抑制了木质素的生成。