Mahfooz Sahil, Srivastava Arpita, Yadav Mahesh C, Tahoor Azram
1Department of Biotechnology, V.B.S. Purvanchal University, Jaunpur, Uttar Pradesh 222003 India.
5Present Address: Division of Plant Microbe Interaction, CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow, Uttar Pradesh 226001 India.
3 Biotech. 2019 Sep;9(9):340. doi: 10.1007/s13205-019-1872-8. Epub 2019 Aug 22.
Frequency and distribution of long-SSRs were studied in 18 phytopathogenic prokaryotes. Higher relative abundance of the long-SSRs was observed in phytopathogenic prokaryotes when compared to non-pathogenic control. The frequency of these SSRs was positively correlated with size and GC content of the genomes of phytopathogenic prokaryotes. Interestingly, phytopathogens with higher GC content in the genome were found to posses longer repeat motifs of SSRs, whereas those having lesser GC content were harbouring shorter repeat motifs. Higher abundance of tri- and hexa-nucleotide repeat motifs were the characteristic of actinomycetes, where as higher abundance of mono- and tetra-nucleotide repeats were the characteristic of the mollicutes. The maximum relative abundance and relative density of SSR were found in the smallest genome of host-adapted pathogen Aster yellow, however, length of microsatellite repeat units was the least. On the basis of presence of SSRs in the housekeeping genes, a phylogenetic relationship between these phytopathogenic prokaryotes was deduced and compared with the phylogeny developed based on 16S ribosomal RNA gene.
在18种植物病原原核生物中研究了长串联重复序列（long-SSRs）的频率和分布。与非致病性对照相比，在植物病原原核生物中观察到长串联重复序列的相对丰度更高。这些简单序列重复（SSRs）的频率与植物病原原核生物基因组的大小和GC含量呈正相关。有趣的是，发现基因组中GC含量较高的植物病原体具有更长的简单序列重复序列基序，而GC含量较低的则具有较短的重复基序。三核苷酸和六核苷酸重复基序的丰度较高是放线菌的特征，而单核苷酸和四核苷酸重复的丰度较高是柔膜菌纲的特征。在宿主适应性病原体 Aster yellow 的最小基因组中发现了简单序列重复（SSR）的最大相对丰度和相对密度，然而，微卫星重复单元的长度最短。基于管家基因中简单序列重复（SSRs）的存在，推断了这些植物病原原核生物之间的系统发育关系，并与基于16S核糖体RNA基因构建的系统发育进行了比较。
