植物防御素基因家族结构、功能及调控研究进展

Research Advances on the Structure,Function and Regulation of Defensins Gene Family in Plants

防御素(Defensins,DF)是抗菌肽家族中最古老的一员。植物防御素是一类包含45-54个氨基酸残基,含有半胱氨酸(Cys)稳定的αβ模序,与哺乳动物及昆虫抗菌肽的亲缘关系非常密切,大部分植物防御素在体内被合成为具有信号肽序列的前体,并被分泌到胞外空间。植物防御素在宿主防御系统中起重要作用,不仅可抑制一系列的植物、动物及人类体内的细菌、真菌,还可杀伤一些肿瘤细胞及病原虫。植物防御素广泛存在于植物的花、茎、叶、果实、根和种子中,具有抗菌、抗肿瘤、抑制酶活、作为离子阻断剂和增加耐受性的功能,可作为新型的杀菌剂或新型的抗生素类药物。随着抗生素导致的耐药菌株的出现,对植物防御素的研究就显得尤为重要,特别是因其有效的抗真菌活性,植物防御素在作物抗病基因工程方面具有巨大的潜力。主要介绍了其发现、结构、类型、逆境调控功能、作用机制以及外源表达植物防御素基因等方面的最新研究进展,有助于将来对植物防御素基因家族进行更深入和全面的研究。

As the most ancient antimicrobial peptides （ AMP ）, plant defensins are small cysteine-rich proteins of 45-54 amino acids and a cysteine-stabilized αβmotif that are closely related to insect and mammalian defensins. Most plant defensins are synthesized as precursors with a signal peptide sequence and are secreted to extracellular space. Plant defensins play an important role in the regulation of host immune by not only inhibiting a range of bacteria and fungi from plants and human and also killing some tumor cells and protozoon. Plant defensins are widely existing in flowers, stems, leaves, fruits, roots and seeds of plants, and have the functions of anti-bacteria, anti-tumor, inhibiting enzyme activity, making ion blockers and increasing tolerance, thus can be used as novel fungicides or antibiotics-type medicine. With the appearance of drug-resistant strains resulted from using chemical antibiotics, the study of plant defensins becomes extremely important, especially because of their potent antifungal activity, they have huge potential for engineering disease resistance in crops. This paper reviewed progresses on the discovery, structural characteristics, classifications, exogenous expression, functions and mechanism of defensins in plants. It will help to elucidate the molecular bases of their function in plants more in-depth and comprehensive in future.