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独脚金内酯(strigolactones,SLs)是一类新型植物激素,D27基因是独脚金内酯生物合成途径中最上游的调控基因,且该基因调控SLs的合成是一个可逆的过程。本研究根据水稻、玉米、高粱、二穗短柄草4种禾本科作物的D27基因核苷酸序列保守区域设计引物,以甘蔗品种ROC22的c DNA为模板,利用RT-PCR和RACE技术,从甘蔗中克隆出D27基因的c DNA全长序列,命名为Sc D27,Gen Bank登录号为KP987221.1。该基因序列全长1379 bp,包含一个867 bp的完整开放阅读框(ORF),编码288个氨基酸残基。Sc D27编码的蛋白质分子量为71.58 k D,理论等电点为5.04,是一种非分泌性蛋白,主要分布于叶绿体上,该蛋白的保守区可能具有2个锌指蛋白结构域(Zn F_TAZ和Zn F_A20),且不存在信号肽;该基因编码的氨基酸序列具有较高的保守性,与高粱、谷子、大麦、短穗二柄草等禾本科植物的D27氨基酸序列相似性在70%以上;Sc D27基因在甘蔗各组织部位均有表达,其中茎尖和腋芽中表达量较高,叶、茎和根中的表达较低。此外,Sc D27基因在甘蔗茎尖中的表达受PEG、盐胁迫、磷缺乏和营养缺乏的诱导,推测Sc D27基因是甘蔗独脚金内酯生物合成途径中响应非生物胁迫的关键基因。
Strigolactones (SLs) is a new type of phytohormones. D27 gene is the most upstream regulator of strigolactone biosynthesis pathway and its regulation of SLs synthesis is a reversible process. In this study, primers were designed according to the conserved regions of D27 gene in four gramineous crops of rice, maize, sorghum and Brachymysta, and c-DNA of ROC22 was used as a template. RT-PCR and RACE The full length cDNA of D27 gene was cloned from sugarcane and named Sc D27. The Gen Bank accession number was KP987221.1. The full length of this gene is 1379 bp and contains a complete open reading frame (ORF) of 867 bp encoding a polypeptide of 288 amino acids. The protein encoded by Sc D27 has a molecular mass of 71.58 kD and a theoretical isoelectric point of 5.04. It is a non-secreted protein mainly distributed in the chloroplast. The conserved region of Sc D27 may have two zinc finger protein domains (Zn F_TAZ and Zn F_A20), and no signal peptide existed. The amino acid sequence encoded by this gene was highly conserved and its similarity with D27 amino acid sequence of gramineous plants such as sorghum, millet, barley, Sc D27 gene was expressed in all tissues of sugarcane, in which the expression of Sc D27 gene was higher in shoot tips and axillary buds and lower in leaves, stems and roots. In addition, the expression of Sc D27 gene in sugarcane shoot tips was induced by PEG, salt stress, phosphorus deficiency and nutrient deficiency. Sc D27 gene was speculated to be a key gene in response to abiotic stress in sugarcane strigolactone biosynthesis pathway.