大白菜干烧心病原菌Pantoea ananatis的生物学特性及全基因组序列分析

Biological Characteristics and Whole Genome Sequence Analysis of Pantoea ananatis Which Causing Chinese Cabbage Tipburn

大白菜干烧心病主要包括两种类型:细菌性干烧心和缺素(钙元素等)性干烧心。2019年,我们首次报道了泛菌P antoea ananatis能导致大白菜细菌性干烧心病的发生。本研究即对P. ananatis Y2菌株的生物学特性进行分析,并对其进行全基因组测序。结果表明,发病初期,大白菜内部球叶边缘呈水渍状腐烂,后期所有内部球叶边缘腐烂,而整个发病过程外部球叶无明显发病症状。在NB培养基上培养,P. ananatis呈圆形菌落,菌落直径0. 2~0. 3 mm,表面较为光滑,边缘整齐;培养初期为乳白色,后期变为深黄色;革兰氏染色阴性,单个菌体呈杆状,大小(0. 92~2. 87)μm×(0. 64~1. 25)μm。P. ananatis基因组大小为5. 26 Mb,鉴定到4 955个编码基因,109个散在重复序列,223个串联重复序列,111个非编码RNA,15个基因岛,6个前噬菌体和1个CRISPR,同时在GO、KEGG和COG数据库中对编码基因进行了通用功能注释。本研究有利于加快大白菜干烧心病的研究进程,对全面揭示大白菜干烧心病的分子机理及培育优质、高产、抗病大白菜品种具有重要意义。

Chinese cabbage tipburn is defined as two types which caused by bacteria and calcium deficiency,respectively.In 2019,we first reported that Pantoea ananatis could cause bacterial tipburn disease in Chinese cabbage.In this paper,the biological characteristics of Pantoea ananatis Y2 strain were analyzed,and its whole genome was sequenced.The results showed that the inner leaf edge rotted as water stains at early stage,while all the inner leaf edge rotted at later stage.There was no obvious symptom of outer leaves during the whole disease process.When cultivated on NB medium,Pantoea ananatis formed round colony with 0.2~0.3 mm of diameter,smooth surface and neat edges.It was milky white at the beginning of the culture and became dark yellow at the later stage.Gram staining result showed that it was negative bacteria;the single strain was rod-shaped,and the size was(0.92~2.87)μm×(0.64~1.25)μm.The genome size of Pantoea ananatis was 5.26 Mb,and 4955 coding genes,109 interspersed repeats,223 tandem repeats,111 non-coding RNAs,15 gene islands,six prophages and 1 CRISPR were identified.The generic functional annotations of the coding genes were conducted in GO,KEGG and COG data bases.This study would be helpful to the acceleration of research process of Chinese cabbage tipburn disease,and it would be of considerable significance to fully reveal of the molecular mechanism of Chinese cabbage dry heartburn disease and breed of high-quality,high-yielding and disease-resistant Chinese cabbage varieties.