Identification of Gram negative bacterium Candidatus liberibacter asiaticus (Clas) causing Citrus Greening Disease by Multicopy gene
1Ishu Priya, 2*Rashmi Saini and 3Mohammad I. Ali
1Department of Life Sciences, Mandsaur University, Mandsaur-222001 (India) 2Department of Zoology, Gargi College, University of Delhi, Delhi-110049 (India) 3Faculty of Life Sciences, Mandsaur University, Mandsaur-222001 (India) *Corresponding Author Email: dr.rashmisaini@gmail.com
ABSTRACT
A non-cultivable proteobacterium called “Candidatus liberibacter asiaticus” (Clas) is linked to citrus Huanglongbing (HLB, yellow shoot disease), which is currently endangering citrus production all over the world. There are five copies of the gene nrd B, which codes for the β-subunit of ribonucleotide reductase (RNR), a key enzyme in bacterial proliferation. Three multicopy nrdB gene copies were in long form (nrd BL, 1,059 bp), and the other two were in short form (nrdBS, 378 bp). nrdBS had no active sites and shared >99% of its identity with the 32 end of the long form of the nrdB gene (nrdBL). The CLas nrdB gene sequences in Eubacteria developed a unique monophyletic lineage. Using 25 HLB samples taken from Northern India, a nrdB-based primer pair, nrdBL2F1/R1, was created and tested using PCR to take advantage of the high copy number characteristic of the multicopy nrdB gene. Hence, the nrdB-based PCR offers sensitive and accurate CLas detection with a wide range of applications, particularly for the early identification of HLB. This aids in restricting the disease’s spread to healthy plants and contributes to maintaining the citrus crop. The present study proposes a method for recognising pathogens in their initial stages and afterwards restricting their further spreading, assisting in the management of Citrus Greening Disease.